The AM Forum

I built a rig last spring and got it working reasonable just today. It is a VFO , a hartley in one half of a 12sl7. That is fed to the grid of a 50l6. The other side of the tube is the modulator fed by a electro mechanical carbon mic circuit using a # 3 hand mic. A parallel tuned circuit is in the output. A pot allows one to find the best balance between screen voltage and modulation input. As far as working it does but power output is very low. Stil the signal is very readable. SO I built a 6l6 linear. It would drive it but still power was less then a watt. It wasnt getting enuf drive. SO today I made a driver (6v6) or basically another stage to drive the linear.  It works. But power is not huge. Maybe 5 watts out on a good day. Partly because you have to run the tubes in class A mode. Partly because a VFO doesnt have the suds a Crystal controled Power osc does. Partly because of the simple screen modulation circuit. It was an interesting experiment and it works however it is not really practical (although I will be using it on 7115 to 7120 kcs mornings before 10 and afternoons before 4. ) This set is a transciever having the same two tubes in the other half as a regen and audio amp and PA. It is an AC DC set.
I have another 50l6 TX I use on Cw . It is a crystal controlled rig and makes pretty good power for a one tube deal. I think it could be plate modulated without too much trouble  however first I want to try cathode modlation as it is cathode keyed so that would be a no brainer. Moderate power homebrew AM fascinates me. I use a regen also with the 50l6 crystal controlled set. The 813 rig idea is intriquing . Maybe  a 6146 crystal osc with plate modulation would be a fun build.
Don
I have

Crystals used with RCA's rig back then were physically larger than the FT 243's most of you are thinking of, let alone HC 6 u's.  An 813 even in an electron coupled (the gentlest to crystals) circuit would crack one of your good buddy rocks instantly unless you were a very good tune-up expert.  ;D

I would seriously use a 6CL6 or 6AG7 as an EC Osc. Into the 813 for a one or two band rig, fundamental or first harmonic.

Here's the MOPA King:

http://n4trb.com/AmateurRadio/GE_HamNews/issues/GE%20Ham%20News%20Vol%2003%20No%205.pdf

Today I did cleanup of the whole circuit (The Pa not the main rig) to move it from a experiment to permanent.  I added a 100ma bulb in the parallel 6l6s plate supply just before the RF choke . Probably should have bought a 150ma as it gets a bit bright but lasted a 1/2hr with no trouble. Dims when you tune to resonance. I also added a key jack for the B- circuit so I can drop the amp out when not speaking. I moved the tubes to even spacing (I use a modular breadboad design for tubes and terminal strips then prewire as much as possible the screw the assembly in place. )When I was done cleaning up all the jury-rigged connections and had everything tucked way power output came up considerable. Showing on my mickey mouse (RS ) meter between 7 and 10 watts. Plates are 310 volts under reasonant  load and appears judging from the 100 ma bulb about 60 to 70 ma. (Almost full bright but not quite. ) I called CQ for a bit around 7115 but no takers today. Anyway, It is done and working. I am thrilled. There were moments I wondered. Tis a real adventure when the only schmatic is the one you draw!
So if you hear a PW in and around 7115 to 7140 could be me. I use a WWII carbon mic so you will be able to tell.
Don Ve3LYX
Here is the top view of the amp. The rear black 6l6 is the driver and the two "tall boy" EH 6l6s are the power tubes. They are supposedly good even to 600 volts. I have a HB step adjustable supply for that. I will check it out tomorrow to see if I can get even 575V with enough current for a test. Let me see, if I double the volts................ mmmmmmmmmmmmm.

USA cannot work fone below 7125 (7130 for AM).

Im surprised nobody mentioned the 4D22/4D32 in the 7 years of this threads life.

Two in the final with a 5763 or 2E26 driver and a pair in the modulator in AB2 with a 12BH7 driver.

One big isolation transformer with voltage doubler and quadrupler for all the B+
or right off the line for the brave :o

Carl

True, Ok, I will use my 7140 marker and work there as well. I am going to try late tonite just to see. Probably the band will be full of broadcasters but I want to see.
Don
BTW Carl, this transceiver is right of the line while the linear runs on a regular PS.

C1 will work, used it for gating pulses. No idea how it stacks up for RF but with enough bias to make for a narrow pulse and enough HV and screen volts, it'll do a good job!

N2DTS built a rig with two 4D32s in the final. Can't remember the modulators.

It's a crap shoot. You may have less QRM below 7125 but also less people to return your CQ. Very few BC stations (some nights none) in the 7125-7200 range these days.

It was pretty noisy but I gave it a shot anyway for 15 minutes off and on. I am just a hair under 7140. Will try in the morning around 9 am. Can't monitor now because I have enuf power to drive my rxs into overdrive. I need a crystal set of 7140. :>)
Don

Steve,
 Yes, N2DTS worked me with a pair of 4d32's mod. by pair of 811A's., Dec. '06.
Then I logged him with three 4D32's mod. by I believe the same 811's in Jan. '07 and I think discussion mentioned wanting to use a pair of 4D32's as modulators. Maybe he eventually did this.

His reasoning is a relatively lot of power using relatively low plate voltages.  Have to agree and am also surprised more don't use them, particulary in the big dump of them on the market not too long ago as mentioned.

your friend over the mountains,
-Radial Rick.

Yep. And not much drive is need with the 4D32s too.

Hope to hear you on the air soon Radial Rick.  ;)

6L6's are notorious and even a 6V6 will crack a crystal if you are not careful. These monster beam power pentode oscillators are novel but really are for BIG blanks like those WW2 BC-610 jobs only.

Mike WU2D

Any tube can work with a FT-243 (Not one of those Carling specials with a HC6 mounted inside) as long as the current is kept low. Thats what the pilot lamp in series with the crystal was used for.....a visual indicator and a fuse for dummies ::)

QST ran a test on octal tube oscillators pre WW2 and concluded the 6AG7 was the best but I dont remember all the criteria involved. The 9 pin version would be the 6CL6.

Carl

Was working on another one today. 6sa7 osc with modulation and 2 6sl7 tubes. One a speech amp supplying modulation to the 6sa7 and one a two stage rf PA boosting the output to a useable level.  6sa7 seems to have laid down on me. Was oscillating but would die out . Now nothing. I dont have another so I will have to look around for a spare to try. I have checked the circuit several times and found a few mistakes but I may have overlooked one even yet  except it was oscillating yesterday.  Anyway other than find a 1/4 jack for the mic input and fixing the osc or swapping the tube it is done. It should have enuf tickle to work with my triple 6l6 PA. I am hopeful. Here it is. I started this a year or so ago. I also built, today, an HF crystal set for in shack monitoring. I bought nothing. Everything was in my junk box. This low power basic style stuff really has my interest. The comments on the 4 D 32 tubes I found quite interesting as well. 100 watts at 600v. Decent!
Don Ve3LYX

Could you please post or send me a schematic for that circuit?
Thanks
Carl
/KPD

Here's a site with completer rundown on the 6CL6 which is a 9 pin minature copy of the 6AG7, also why an ECO is a great oscillator and all kinds of neat retro stuff.  ...resurrected and modernized an old 813 transmitter and everything !

-Includes references to QST's tests too.
I think the whole site was referred to in an earlier series of postings on AMfone.
I've kept the link for some years and have wanted to build up something similar starting with the 6CL6.

http://faculty.frostburg.edu/phys/latta/ee/6cl6xmtr/6cl6why6cl6.html (http://faculty.frostburg.edu/phys/latta/ee/6cl6xmtr/6cl6why6cl6.html)

Could you please post or send me a schematic for that circuit?
I can send you a link for the basic circuit. From the 6sa7 forward (6sl7) is my own and is yet to be drawn. Bsically first triode section biased properly with an Rf choke in the plate lead from B + and coupled to the next stage (of the same tube) by  150 pf cap where the process is repeated which then feeds a parallel tank circuit which coules the output to the antenna (or big amp) with a 5 turn link wound overtop and centred. I have removed the PA tube when trying to get the vfo back going. I will send the link right here in a minute. The idea started life as a Am broadcaster for home use.

Don Ve3LYX
I can't remember where I got the circuit. It says on it AM Transmitter 2. Because the basic cicuit isnt mine I dont think I could post it here as an attachment. I can however send it to you privately.

I have been beating on a hb transciever for almost a year and only had one QSo with it. I built a new linear but never had success with it. it seemed good and would po the watt meter. (Mickey mouse plastic Rs thing) but i suspected that was in shack radiation rather then real antnena output. SO i got my old standby, never lies watt meter. AKA light bulb with 50 hm coax and hooked it up. Not even a twinkle. i went through the Pa and the one thing I found was the final plate tune wasnt very definate. Seemed like it wasnt on frequency. Not resonant. I looked over the circuit and test, bypassed and fooled around t no avail. I finally looked at the RFc  in the plae circuit. it was a homemade one. I often make them for regens . I wondered if it was shy a few turns. (or perhaps a few hundred turns). i dud though my junk box and found one from a 1923 radio I had stripped. I swapped it for my homebrew. Instant success.  Plate circuit tunes sharply dipping my indiactor ncely on resonance. (a 100 ma bulb) So now the acid test. I hooked up the bulb dummy and turned it on. Success. Bulb lights to about half brilliance on resonance. Since it is link coupled it has to be Rf and not stray stuff either. I ran the power supply clip up to full voltage and reset it all. Draws about 100 ma  (plate current indicator lamp fully bright on resonance. ( too bright either side of it. I will be working to need a 150 Ma indiactr today so if any are around I will be testing on 7120 and 7140 throughout the morning. till about2 pm EST. if your not good on 7120 a sig report here would be welcome. I was going to give up on it but couldnt quite do it. ! too soon old too late Schmart
Don VE3LYX

I now have power up to a pratical level. Today I had a guest operator stop by and had them watch everything while I bricked it and went for a quick drive wih a portable recvr.  About 4 1/2 minutes. About a 1/2 mile away the rx was stil a bit overloaded but at about 2 miles away the carrier could still be heard nicley. Hurried back before the smoke rolled.  It has been my experience that anything I can hear at that spot will work 400 to 600 miles on a good night with a sked. So now that I know it is putting out a decent signal it is just a matter of time.
Don

Re The 6sa7 Am transmitter circuit. I got my new tube yesteray and got the osc and RF amp running well BUT it would not modulate. I spent late yesterday and some of this morning working on the circuit. I am colour blind so I went through and measured a lot of the resistors I had used because this is my usual fault. I found one too! I thought it was brown, but it was green. (Not good when that is the first colour band!) Anyway it would not modulate. I traced the circuits I had and found nothing. I replaced some .01 caps I had had failure in (bad batch of surplus rejects)
Nothing. I went through the circuits as it was posted on the web. First stage of the speech amp had a 15K resistor in the cathode leg. That seems odd I thought. Second leg was a 4.7K bypassed. I checked a few other similar circuits to see if I was nuts . All less then 5 K . I surmised he meant to enter 1.5K  so I tried it. Instant success.   Probably 2.2K would be typical. So I now have a 40M low power AM rig. I added the second 6sl7 as a driver  Pa and used a parrallel tank in the plate of the PA. I linked it out with a 4 turn link,soldering a 12v 220ma to the link wires for a dummy load. Actually lights the buld fairly brightly at resonance . Now I have to tame it a bit . Shield the VFO from me and add a vernier drive perhaps. Then I will see if it will drive my tripe 6L6 linear.

You are doing a gutsy, hands on job there, Don.

PW or QRO, the job is the same. 

Keep up the good work! :D

73DG

Thanks for the encouragement.
This afternoon I tried cleaning it up. I removed 2/3 of the movable plates from the VFO variable cap. (approx 365pf) and replaced the missing capacity with a fixed 151pf "punkinseed". This brought my tuning in band totally and easier to control. I left the PA tank as is. It seemed to like that change. I then took all the mikes I had and tried them. It only likes the old magnetic stuff similar to an earphone. I had a 1950s telephone mic from an old dial phone. It seems to be something of that nature although it may be intended to use as an earphone. What ever. I took an old AC /DC   set audio transformer. like the ones always mounted on the speaker and connected the high end to the set with a 1/4 plug and the low end to this old telephone piece. Pretty good Audio! I am surprised.  So I am whipping up a homebrew push to talk mic for the rig with the audio transformer in the base. I must have had some RF in the audio before because hooking this in settled the whole rig down on both RF and Audio side. It now tunes smoother, less bothered by my hand. It gets right at it, loading nicely and is much more stable. Even moves the needle on my in shack FS meter! Sounded so good on the monitor Rx I clipped a banana plug to the side of the dummy load , shoved the banana plug in the centre hole of my coax switch, turned it to that position and called CQ on 7145 kc (+ or -) With only a PW I didnt expect an answer but it works good enuf I wouldnt have been totally surpirsed. I am liking it more all the time. Tonite while the XYL is out  may try a 6bl7 in place of the 6sl7 on the RF side. (might be  the wrong number but you know. That old TV sweep dual triode from the 1950s.  same pinout I believe.) I think the 1956 hand book has a rig made with it. Anyway a fun project for sure, this mixer tube AM transmitter.
Don VE3LYX

So I tried the 6bl7. Wow! I lost the dummy load at the instant I hit the key. Wired in a bigger one. Strong for a PW. After about 2 minutes the one side of the 6bl7 , the final side began to develop an orange glow in its plate. I took a picture in the dark . Not knowing what to do, I surmised that since both sections of the tube have the same gird bias, and plate voltage, that it was being driven too hard by the preceeding stage.(of the same tube. ) So I popped a 2k 10 watt resistor in the plate supply for the driver stage  before the RFC. All is good now. Might have been a bit much but I had it in stock. Key down for extended periods with no glow and power is still good.
This rig modulates well. Both my other Am rigs are light on modulation. My DX 60 almost has enuf but not quite.  My homebrew has enuf to be readable but no more. This rig I can set it anywhere I want. From very light to too much. Once I am sure all is well I will stick it on the parallel 6l6EHs linear and see what happens.
Don Ve3LYX
Fun build for me anyway. 
See it is really true! Real radios glow in the dark.

I have spent a lot of time trying different things. I put it on the 6l6 linear and it made decent power. Nothing huge,  but enuf to be effective. Doesnt matter what tube you use on the amp. 6sl7 or 6bl7, since both have sufficient drive. So on the amp I used the lighter one. I got rethinking the glowing PA tube. I didnt think the 6sa7 would push anything hard enuf for that so I decided to try something. I paralleled both sections of the twin triode. I left seperate RFCs in the plate leads and matched the other sections up so they are drive only by the 6sa7. It worked well with either the 6sl7 or the 6bl7.I currently am using the 6bl7 in the PA. I use this rig barefoot. Now. I can get it to wiggle the FS meter so it is making something besides a few  mws. I then turned my attention to the mic. I wanted it to look better. I went to Home Depot, bought some switches and shrink tube and strolled to the lamp aisle looking for ideas. PAYDIRT! They have a lamp called the Theo that looks like an old microphone. It has a halogen bulb that twists in and a weighted base. The height is adjustable by about 3 inches., It was pricey, $35 but I couldnt leave it there. A couple of hours later, I had ground the edge of the bulb at the top, popped out the lens, busted the actual lamp and removed it. I drilled through from the back opening up the holes on the contacts that were already there. I soldered the wires from my mic element to each of these contacts then taped the whole assembly. Mic cartridge to the reworked twist in bulb. I used an industrial vinyl tape that will be here long after I am gone.I clipped the power wire short and installed a 1/4 inch phone plug. I drilled the base and routed out a spot for a push button switch for push to talk and ran a wire for it taping it to the other wire every couple of inches so it looked like one. I left it a bit long so I could install a 1/8 plug on it for the push to talk and be able to have it reach that jack which is on the other side of the radio.  (It grounds the cathode (back to the set. ) which turns on the set other then heaters.) I gave it a test run. Worked good. All it needed was a spit screen. I remembered I had a small kitchen seive from CTC in my garage that I had bought for something. I wondered if it was close. EXACT fit. Here is a photo. I am calling this the HD104. (HD for Home Depot) I am really happy with the look and the function as well.
So I am running both my homebrew low power or medium power rigs on 40m as often as possible. 7120 to 7140. If your spinning the dial check there. Who knows? You might actually hear me.
Don VE3LYX

Built an Amp for the rigs. A bit more serious. Used a 6293 (more or less an industrial 6146B). The 50l6 in the HB transceiver drives it nicely. I havent measured it all yet but it buries the FS meter in the shack even when adjusted back to 1/4 pot setting. So whatever it is it is a lot more then before. The 6l6 pa would give it about 2/3 with pot in most senitive postion so definatley a large  improvement. PA hops in and out on its own. Stays at idle till I hit the transmit switch and returns to idle instantly. I tried everything I ever wanted to when building this one but wound up with a conventional circuit in the end. I have done testing and run in at 267 volts  with no tx on. Once I am comfy all is good I will pop it on the 580 volt supply. Bias, neutralization and input tune are all accessable from the front. Output PI setup is a very HD switchable stand alone unit I built sometime ago for all bands. Seems to work well. Oh yeah. All built on wood. It was fun trying all different types of coupling , front end tuning or not and testing to see what worked and what didnt. Cost was zero. Built from the junk box. Dont remember what I paid for the tube. Seems to me I bought two at $20 per. The other is in my DX60 now. 
Hopefully we will have enuf suds now to make everyone happy.
Don Ve3LYX

Sounds like a good project there Don. Do you have a way to measure the plate current on the final and the actual power output? I would give you a better idea of what power? the final is putting out.
I thought this thread was originally about a "medium power" AM rig..ie. in the 250w output class? ;D

Sure. Of course.  
I may wire in the meter perhaps this afternoon. or I may just wire in a pair of jacks and use a light bulb indicator .By hooking in the ma meter and unscrewing the light bulb I get an actual reading.  I am however getting pretty good reading plate lamp brightness now. Seems to jive well with the actual reading in ma. Just had it on for awhile . Still works good this morning which is always a good thing.;.) I like how it "parks" so nicely when the TX is off. I may try the mixer tube rig on it this afternoon as well. I had built this circuit a long time ago and worked  Tim with it, (before I got the DX60) just hearable , with a 50l6  I refined it a bit and rebuilt the entire deal with a 6293 but since both are beam power tubes not much different other then socket pinout because of Plate cap up top. I like not having to switch the amp on and off which is why I liked this circuit I think. As soon as the tx output upsets the apple cart (grid) on she goes and it doesnt hang up coming off either so I can hear in the rx immeditaley.
Don Ve3LYx

I installed a scrap meter I had from a busted RS SWR deal. I made a shunt for it. First one was too light, second was about perfect for low/middle indicating.I will calibrate it later as the meter cover merely pulls off.  I found the Quin........nt current not to my liking. A wee bit high. Grid was going 1.36 volts positive at rest. I decided to get creative. A  pair of 6146b tubes often are installed with the cathode negative about 5 ohms. This will bring it to 0 volts or just below. 5 ohm or even 20 ohm resistors are scarce here. Flashlight and dial lamp bulbs though we have lots. One, a #40, measured 5.6 ohms. I wired it into the cathode circuit and bypassed it with an 01 cap. Worked pretty good but still a bit high although certainly liveable. I had a 52 bulb. It was double the resistance. I tried it. At rest current is now just below what it is with a signal driving the grid. I was surprised to get it there. I thought it might be too far down and would shut the tube down. It works nicely.  So I now have a running light, a cathode resistor, a decent no signal current and a poor boys input power indicator all in one. It also functions as a ready light since there is no current flowing till the tube is warmed up. The big long deal in the antique box is a transceiver. Two tube regen, two tube TX , single tuning control, with screen modulation by a electro/mechanical carbon mic circuit driving a half of a 12sl7 which modulates the screen of the 50l6. No 3 hand mic is used. The amp sits next to it. A single 6293 PA, tuned input feeding the big antenna tuner but also PI output L & C next to it. Huge, crude perhaps, but F.U.N.  Everything built on wood which eliminates a lot of the shock hazards and is traditional besides. How much power? It lights the cathode resistor 52 bulb as bright as I dare on transmit but will sit for two hours at rest no trouble producing no RF till you tickle its gizard with the transceiver. I am happy. Working on a solid 500 volt B+ supply today. (rig is with full signal now measuring 342v plate between PS side of RF choke and Grd or B- )

If you can get your tx on 3725kc Sat. morning we will listen for you Don. 8:30am..Tim is werking I think, so you'd have to settle for Ken and I and others :D

Al

Sure Al, thanks. If conditions are bad I will at least say hi anyway otherwise I will be there. .
Don Ve3LYX

I made the 500+ volt power supply today. Finished and tested it about an hour ago. That made the tube sit up and take notice.  When driven about 190 ma. I will measure the voltage tomorrow. Not good to fool with dangerous stuff when you are tired. I used five 24 volt transfomers used by the heating industry. There are literly hundreds of these around for the asking. Very well made and designed to be under power forever. I joined the five 24 volt secondaries in series and fed them the 117 house power.  I also linked the matching 117 volt primaries together for what are now my secondaries. Used some 1n4004 diodes to build a simple full wave rectifier. (half a bridge basically. ) I found a matched pair of can electrolytics  of the 400 WDV and 10mf. First I taped the cans so they could not short then put them each in a section of wax paper cardboad roll. I then taped the whole deal together. I wired one section of each in series with a set of resistors wired in to keep voltage split across each and also to act as bleeder resistors. (approx 100 ohm per volt. ) I took apart an old flea market buy six volt battery charger and liberated the transformer for my filment supply. It was a centre tapped deal so I have both 6 and 12v. Unfortunately it is a bit high so I will have to cut it down about a volt under load. I found a old neon lamp and an switch in my junk box and built it all inside a 5/8 plywood enclosure. I mounted an octal socket on the lid and wired it from below. I use always and never change the 7AC tube wiring. Heaters 2&7 Plate 3  kathode 8. I wire 12v filment to pin 1 when I do as it is a nomally unused pin so if I have a 12v unit to plug in its heater will be 1 and 2 instead of 2 and 7. This way there is no chance of ruining a tube by forgetting to switch heater voltage on the PS. It is just wired for what it needs from the start. I was nervous firing it up and a bit worried about the tube heater voltage being a volt high but also aware they allow for that. Should be ok for a short test at anyway. Took a milisecond to settle down as the filters charged up and got to work but after that it was solid.  I ran it for about 20 minutes. Transformers are cool as cucumbers. No smoke nothing warm. I wasn't surprised. There is a lot of iron in five of those transfomers. Why wood? No chance of an accidental shock from a metal chassis. Cost? I had to buy a fresh supply of brass wood screws so I am out $9.56 . Everything else was in my junk box. The transformers were given to me by a local contracter who was throwing out barrels of them, brand new, unused.
Don Ve3LYX

"There is a lot of iron in five of those transfomers."

I WAS WRONG. This was a really dumb idea. While quiet and not hot voltage sags like a New Years Resolution under heavy load. Tube likes the high voltage and is bult for extremes but once it is fully warmed voltage drops as current rises. I have another 600 volt supply but it is too noisy.  (HUMMMMMMMMMMMMMM. ) Anyway for now I am back on the old supply. Also the little 6sa7 rig is done and is working very nicely. Far better then I would have thought. Push to talk, full modulation , reasonable power for a PW rig. I am very happy with it. Where do the PW AM guys meet? Today I started on an antenna project. Probably another dumb idea but I learn by trying things. Even when they dont work I still learn.
Don VE3LYX

" Today I started on an antenna project"

I don't think she'll fly in less than a full gale.


klc

Or tie it to a hot air or weather balloon and let er go... ;D

Theres a group that meets on 3765 on Tuesday mornings 10 am Don. Local VE3s. Dave ORP in Kingston and Dave BLB in Niagara. It used to be called the Wireless #19 Set Net. But none of the guys ever use the #19 set on this net..and they are all on slopbucket. That is one ugly looking PW rig too..not my cup of tea. I guess that tx is too PW and yellowy sounding for them to carry on a QSO with it.

Al

Ugly? OUCH! I love making stuff. I thought the little 6sa7 mixer tube rig was cute. I make my own radios, my own fiddles, my own dragster for racing. Even the mic for the 6sa7 is one of my creations made from a halogen lamp stand. I have an aversion to factory made. Seems to me like cheating. However, I do have a nice TS830S which I have owned and operated for 30 years. I may pop up there. I have been working on my ARC5 sets and have the Rx working perfectly and the Tx on frequency and coming along but I need to make a modulator for it.
The antenna does look like a kite now that you mention it. I will finsh it today and test it with the GDO for tuning and then the Impedance meter if it is where I can use it. I found a version of it in a 1925 Radio News. At worse it can be my Rx antenna. At best I will be able to burn a very directional hole in the atmosphere to Bethany. While searching for info on the web I discovered so many vastly different reports on multi and single turn loops I decided they were for the most part blowing smoke and dont really know. It is like that in the race engine business too so I know what baloney sounds like. There if in doubt I tested till I found out. It paid me back huge and I began to know rather then guess or act like a parrot repeating someone elses baulderdash. I am hoping it is so here too. When there are several opinions most are wrong I have found. Smokey Yunick once said "One good experiment beats 1000 expert opinions. " I have found it so as well. When i began building the mixer tube deal I got sidetracked listening to others. Finally I tore it all back to just my mixer tube oscillator and modulator and rebuilt it to my original plan. A couple of minor changes and it worked. I have rubbed on it since and improved it some both audio wise and power wise. It has osc tune and PA tune with a lamp in the parallel plates RF PA circuit for a tuning indicator. I has its own speech amp and modulation control and that is centred if you know what I mean. IE mid range is about right. Audio is very good. It has press to talk. Personally I love it. Couple of watts actual output. A real fun PW AM rig. I may build it its own linear. Trouble with low level modulation is when you amplify it you get all the good and the bad ie Hum etc but this little guy is excetionally quiet so it will probably do well. Once I have everything to my liking I am duplicating it in a file box for a portable Am station with 9 pin minature tubes. (6be6 and 12ax7s ) and an old style vibrator power supply in the lid along with its own rx.
Black rig at the bottom right next to the 6sa7 rig is my T1154 sinplifiied circuit. I work on it from time to time when I am in the mood but it seems to me anyway a somewhat complicated circuit. Has to be a good day.  
Don Ve3LYX
UPDATE!
The kite antenna is up! (no pun intended)
I finished it and attached a coax connector . Tested it in upright position free of magnetic influences with my GDO. Natural freq is 4.9 mhz. Coax will act as a capacitor to some extent so I will retest it with the line OR I can put a cap in a Tim's coffee can and set it out here for 80M. I was going to short one turn and see if it would also do 40M but then I realized North American AMers on 40m other then a handful at 7295 afternoons are more or less an urban myth. Anyway I opened up an old cement slab hole for a rotating cloths hanger that was here when we came 35 years ago and made a stand in the shop to mount it for now at ground level.

Don,
I've immensely enjoyed looking at your works in progress.  Experimentation, logical application and the joy of building abound.  You're a true ham.  From your detailed write-ups I felt I was right along side of you.
Kudos

Hi Don,
I was referring to the #19 set as being ugly, not your HB gear... 8)
Any holes you burn over this way with your signal would be most welcomed for sure.
Al

Thanks folks.
Today I got it up and running. I had read loops have a very low impedance so I made a little transformer on a piece of 1 1/4 PVC pipe . ( 9 turns of #16 wire close wound with two and 3/4 turns )approx) of stiff #12 wound over the centre. I connected the #12 to the antenna to complete the loop and connected the 9 turns of #16 to a length of 75ohm. (Cause I had it and cant buy 50 ohm anywhere nearby. ) I put a union in the 75 and conected it to a long length and bored a hole in the house above the window in my downstairs shack and fed the wire in. Maybe it was wrong but I figure if the loop is say 25 ohms then this little deal should work like a similar deal does for interstage coupling in a transmitter , PA or what have you. I know this will throw the tuned circuit off but you gotta start somewhere. I put the big long rig on 80 m and switched on the 6293 AMP and tuned everything in. It worked but could have been better. After supper I put a meter in the circuit. A HD SWR meter between tuner and antenna. Some power but not as I hoped. for some dumb reason I thought to try 40 M and tuned up on 7145 then switched on the Amp and trimmed everything. Something must be wrong. FS meter which is always on in my shack pinned its needle. So did the SWR in forward before I even got it trimmed . Had to cut both meters back on the their pots several times and it responded to tune trim real well. Tried the big  long rig out for a few CQs. Nothing back but that is not unusual this time of day.  
Aftera long CQ  saw a wee bit of smoke rising from the homemade RFC in the amps plate. The wooden dowel it is made on was getting warm. And yet plate current pre RFC was in range. So I thought I will try the other tiny 6sa7 rig and put it on the triple 6l6 amp. (one driver and two in parallel making power. ) Same power supply as I used for the previous set up. Same result. Antenna loads well for a first try. Power out according to all indications is very good. SWR was right on 2 to 1 which I know is not good but much better then 3 to 1.
I am kind of surprised and mystified by this result and have to think it through. Then I will try it again on sked with someone. Seems a bit too good to be true.
BTW, When I was feeding the 75 ohm through the windowframe I bored a second  hole and fed through a beverage Rx antenna I had installed but never used yet. Talk about no noise! I thought my rx was broke till I found a station. I also tried "the kite" on my RXs. Both liked it. It too is much quieter then what I was using although not as quiet as the beverage.
Don VE3LYX  

Ah HA! I think I might have figured it out. I never had this Amp, the 6293, on 80m before so I didnt really know of it would tune there. I checked the input circuit and found that the tuning cap plates were full closed for the 80M test. Then I remembered. I used an old AC/Dc table radio cap for the tuning cap. because I wanted better control I hooked the two sections in series (took off only at the two fixed plate connections.)(dual section Variable cap) I had allowed for being able to switch if needed to parallel sections but never had actually tested it or wired that. (needs a couple of short wires and a DPDT switch) So I got out my trusty GDO and tested with plates fully closed as is. 4.5 mcs. Too high. Need more C to bring it down. If I switch the variable cap connections that will do it. SO whether the antenna is as good on 80m as it appears to be  40m I dont know but I do know the 6293 was unable to tune down there as is so power output would have to be low. I will experiment tomorow with switching the C around to get full 80m and 40m coverage. Then repeatthe 80m test and see. The 6sa7 and the triple 6l6 amp are only good for 40M so I could not put them down there.
Don Ve3LYX

I found one reason for funny readings. A bad patch cable. Made a new one today. Have the Amp on 80 M now and according to the in line meter excellant power (even compared with my best of anything else down the Hb shack) however I have been fooled by goofy results before.  SWR on 80 is not good. Time to dig out the Impedance bridge and test. It is a pain because I have to supply a low power RF souce. The big amp does not like runnning there on "the kite" on 40m  but will sit all day there on 80M so for now I will leave it so. Basically I am still thinking this over. Isnt going to be easy. I can see that right now. It will be interesting though, I think. I set it up on 3725 for the weekend. Might get a chance to take one turn with it to see if it can be heard at all at a distance.
Don VE3LYX

Last evening I added a cap in the loop. A 150 variable. The loop now works. I put a low power signal on it and walked around with a portable recieiver wth its antenna retracted.  Very interesting pattern. Strongest field is at 60 degree approx angle from the loop  quieter directly in front of it and very little at the side. Most interesting deal. Am tuned up on 3725 and will pop in there for a CQ now and then as I work away on this when ever it is not occupied.
Don VE3LYX

I was having trouble with the loop or multi loop. Tis a whole new experience. I could not get the SWR down. I know I used 75 ohm coax (because I had it here but still could not get it down to even a readable reading on 80m.) This morning I was about to tear it all apart and forget it. While taking the coax down I saw a kink in it. (like a garden hose, really severe) I guess that is why it shouldnt be used for this.(it is just TV stuff I had.)I straightened it out and massaged it a bit to make sure the dialectric was not  totally squished and then tried it again. I got just under 3 to 1 this time. I began playing with the match  (parralel lines.) I could make it worse but not much better, Just a wee bit. The higher I go in freq the worse it gets. I played with the variable cap in the loop. It makes some difference so I noted how and what. I have been in and out what seems like a hundred times today trying , adjusting, removing, adding etc. I am actually making some progress. I can make it worse, much worse and then return to where I was and make it better again. I am going to leave it for a bit and think on it plus order some proper 50 ohm coax. The rigs and the Amps are working lovely now. Everything is now repeatable. Since this is all tubes I will operate even at that SWR if the band is active. Interesting though.
Don VE3LYX

The loop antenna project has been scrapped. When it was all hooked up using my gdo it was reasonant on 14 to 15 mhz. Using a loading coil of sorts of some 29 turns I was able to get it down to 9.90 mhz and with the large variable tune through (up a half Mhz. ) So it would work on 20mhz and with the loading coil on 10Mhz (which is CW only). To make it work properly on 80M I would need approx 180 feet of wire and 9 turns. And then a loop has a very low impedance (this one measured 4 ohms at the null pont on my impedance meter.) So despite the look and lack of need for severe height I scrapped that project today. Not practcal for what I was trying to do.
Don VE3LYX

Hey Don

I heard you this morning on 3725 and called you in, but you never came back??
Bill VE3CFY was S9 here using his ricebox 25W carrier. I could hear you about S5 here. FYI.
Al

John VE3OMA near Picton ON ran his ricebox down to 5 watts carrier and he was 10 over S9 this morning on AM.

Al

haha the #19 is somewhat ugly but there was never a more devout and perhaps paranoid following of any set except maybe in the radar crowd. Paranoid meaning a rigorous and rigid procedure required to download any technical materials from one of the chief sites for the set (they are free). The #19 must have some very fine qualities to engender that much loyalty. Hopefully I'll get to try one out some day.

I might be willing to try one out too, but the collector crowd has gotten involved with these rigs now and the asking prices for complete, clean units have gone crazy. The 19 sets could be had back after the war and for years afterward, very inexpensively. Radio row in downtown Toronto had overflows of them out the front doors of the stores on Yonge St. from what I understand.
I find it strange that they have this Wireless Set #19 Phone Net, but no one actually uses the set on the Net, and they're all on slopbucket, not AM. To each their own I suppose.

Al

I came back but I think "maw" hadnt finished because when I let go of PTT he was still talking. I only had a minute or so . He had burned through  31 minutes so far this morning. I had to go. Sorry.I ran out of time.
I cant help what the lads in Picton do. This QTH has never been good . I used to live up the road about a 1/2 mile and it was phenomenal . I used a A3 cushcraft there. When I moved here I put it up at the same height. no cigar. I finally sold it to a Russian fellow from TO along with a homebrew 4x250 Hb linear. I played with several set ups and found a vertical worked well here. I was on my inverted L this morning. I can switch to the inverted Vee double bander. Sometimes it works better sometimes not. As the winter closes in it will improve dramatically I suspect.
I am getting ready to go back to finishing my Suppressor grid modulated simplified 1154 circuit. It is about 1/2 done. I am hoping you get your lil fellow on air too. I can hear pretty well here I never use the TX antenna for the RX. I use a 12 inch loop for my CW work on a 12sl7 regen. It can hear anything. I use which ever  antenna I am not tx ing on for the rx here upstairs in the commercail equipment shack. Downstairs I use a beverage for my ears and an inverted L for TX. I could hear everyone this morning. Bill was weak. Mike was solid but not super strong. Ken had a bit of QSB but was readable and you were hurting my ears . Very strong in here.  
Don VE3LYX
BTW I have a Tranco 7-41 transformer. Cant find any specs on it. Any leads?

OK on Sunday morning Don. Maybe get in there earlier or something. That HB 4-250 amp sounds/would sound good now with your arrangement now.

I have/use a 2000ft. beverage/longwire for listening. Its pointed to the NNE. Its great to bring in DX from over the pole etc. but it almost eliminates the local signals here. It is a very quiet listening antenna though.

I brought up the fellow in Picton as a comparable for me here in listening out for signals from your area. ??? Can you git your 830S on there and we could do a comparison/test sometime over the holidays.

Al

There was one of those transformers for sale on Ebay recently. You could ask the seller a question about it.

http://www.ebay.com/itm/212-NOS-TRANCO-7-41-11-62-TRANSFORMER-/370683117830?

Al

2000ft! Wow. I have 136ft I think if memory serves me. Still very good for listening as you pointed out. I got the 80M inverted L up another 5 feet in the middle today. A bit more and it will be free and up another 3ft or so.
I looked on Ebay. He doesnt know any more then me I see. I will have to measure it I guess one by one. Should have a bit of a load I think to be relative. Even a Meg-ohm or two would be better then nothing. It is from a half assembled ICS Oscilloscope kit a friend found in an old house he bought.  Spent this afternoon working on the supressor grid AM transmitter. Got the big tube all wired . Now I need to wire the modulator and the osc into the main circuit. I changed a few things as I have some preferences (IE I like link coils, as opposed to coil taps, for coupling out of the osc and I dont need a CW option nor a EM mic option as I want to ue it with a period correct carbon mic)
Don VE3LYX

Earlier in this thread the 6sa7 mixer tube tx was mentioned. I have one I built and originally used a 6sl7 in the final. First triode section driving triode then switched it to parallel triode RF PA driven by the modulated 6sa7 which is also the oscillator. I had subbed in a 6bl7 which while having the same pinout as a 6sl7 is a rather robust tube. I was doing some measuring on my other Hb rig for Power out and decided to test the 6sa7 rig as well. First with the 6bl7 then I decided to try the 6sl7 back in place. I didnt really expect much difference , same PS so why would there be much difference but there was. While neither is huge power the 6bl7 pushed out 3 times the power of the 6sl7.  Very interesting to me. 
Don Ve3LYX

That series of dual triode tubes are cool.

I'm wondering if the PS and filament transformer would handle a 6AS7...6080..or 6336...those tubes would make great cathode follower direct coupled audio driver tubes to drive class B modulator grids.
I know they were widely used as voltage regulator tubes in some Lambda and other regulated power supplies.

Al VE3AJM

It would be cool to run a 6sa7 and a 6as7. I have several PSs . None too fancy. one is 800 volts B+ no load and very robust.
No DX60, I heard what you said. I want a contact again on the homebrew. I am going to try till I succeed then I will fire up the Dx 60 again. I may anyway. Today I reworked my 6293 Rf PA. I had been cheating using my HD Pi network Hd antenna tuner for the final tuned circuit and did not have one in the Amp. Today I made one up , removed the cap coupling in the output. Built a parallel tuned circuit robbing a variable cap from my 45 TNT (already replaced it with a 1920s bakelite version so it is still operational) Link coupled it out which floats the output free of the other circuits which I like as a matter of fact. I tryed it. It tunes well, dips plate smartly . Will try it next time I hear you fellows on. Tuned up on or about 3725. Feeding a base loaded 80M vertical clamped to the rear deck railing. Power is good, freq is right. Hopefully it will all come together. Once it does I will go back at my ARC5 tx and get it on AM as well. Waiting on some filter caps from TO so I can finish a 600 volt supply for it. 347 volts is too low for good power or real good power, the 800 volt supply scares me when it is on there. just a bit too much I fear. 600 V I think would be perfect under load.
Don VE3LYX

I love the 80m vertical ant that you have there Don. The new caps should help that PS. All said this morning in good humour Don. And now I know that you're listening in too. lol... ;D
BTW, Ken and Bob were both stronger than Tim was..just conditions thismorning I suppose.

Al

No offence taken. I understood . Nice to be missed even. Very interesting here today. I could hear you fine , On the beverage I could hear everyone but on any of the other antennas even the good ones Ken was zip and Tim was moderate which is rare. On the beverage all were good although at different strengths. I am having trouble spotting the HB rig on freq. The Rxs downstairs are too close so it isnt where it appears. ,Probably blocks the input (FET front end) and sneaks in through the If circuits. I turned the rig on and tuned it to  HR 10 upstairs which is on 3725. Hopefully that will do the trick. Very hard to judge the signal. I have a osc scope  also Hb but it has no amplifier and functions only with a higher powered rig like my TS830S. I have a 40 meter monitor which also works for spotting  that is little more than a glorified crystal set. I should make one for 80 too I guess. It is very practical on 40M for putting on freq and monitoring modulation. 
Don VE3LYX

Things are progressing. Did some testing of the 80 Meter vertical using a poor boy tester. A bulb socket and bulb from Lowes Science projects hardware and a loop and a bit of hook up wire wound around the loading coil form above the coil up where it is just wire going straight up. Test looked very good. Bulb is full brillance plus (was half brilliance before when I first put it up.) The reworked antenna loads very well. Makes the Rf amp grunt a bit.  Did some field strength tests today with a bit of help. At 2 miles away unmodulated carrier is easily picked up on a hand held portable while sitting in the car. The QRP CW  rig wont do that on the same handheld and I have worked the Carolinas and Maine with it so I know we have enuf to be heard at a distance under good or exceptional conditions. At just under a mile signal gets strong like you are too close.  Parts I ordered from TO to raise PS voltage to 600 volts have been sent but have not arrived. So I am still at 347v under load. (On a good day Line voltage here is not high either at 110 to 112.) Still set is working well it seems . Modulation can be clearly seen in the cathode circuit #52 lamp I use to keep the grid negative. New tank circuit tunes very nicely. Very definate. Nothing ambiguous about the tune up. Now I need an exceptional day and someone listening on or around 3725 and all will be well. Today I could copy the Ontario Tradesmens Net downstairs on the beverage but upstairs on the inverted L was not too good.  The beverage receiving antenna surprises me almost daily. Spooky quiet noisewise but really has good ears for signals. I should have had one 30 years ago. Like so many I just didnt get it.
Don VE3LYX

Here is a peak under the lid of the homebrew AM transceiver.
left hand side is a regenerative 2 tube receiver and to the right of the aluminum shield is the transmitter section. The common single control variable cap tunes both RX and Tx . On transmit the rx osc is deprived of B plus and visa versa on recieve for the TX osc. Other then grid resistors (grid leaks) the oscillators (a regen is just an oscillator that isnt quite oscillating)are identical and are Hartleys. Both use 1/2 of a 12sl7 dual triode. In the RX the other half is used for a rf amp or buffer of sorts and a bit of audio amp and feeds that to a 50l6 beam power Audio amp which drives a speaker easily. In the Tx the other half of the 12sl7 there is used to modulate the screen of the 50l6 Rf power amp  and is driven by an antique  style carbon mic circuit. The battery is visable in the photo and I cheated here as it is a 9 volt. While the osc/regen tunes both 80m and 40m continuously the RF PA requires a switch to pad it for 80m . The board at the rear is a voltage doubler for the Rf PA giving it around 250 volts plus under load. The unit is otherwise a transfomerless PS  deal . I took this photo today as I was working on moving the freq more centred on the dial and making the Rx and Tx track as close as possible. Got it pretty close but may add RIT to perfect it and give some wiggle room. I dont have a small variable trimmer cap with a decent end or shaft so I didnt do it today. Radio is built from junked radios. almost entirely. Case is a 1920s empty radio cabinet given to me by a neighbour. This is my favourite project. Trying it on 3725 as often as possible.
Don VE3LYX

I seem to be obsessed wih low and medium power AM. Today I had a brainwave (or a brain fart ) I wondered if a complete AM transmitter could be built with one dual triode. My all time favourite twin triode is a 12ax7 and its cousins. I searched the junk box and came up with a 12ax7 and a brand new socket. I wired it for 6 volt use (white twisted pair is the heater conections. ) I joined the plates together and wound the hook up wire around a low value resistor 5 times on the way out making a parasitic suppresssor in the process. A rf value (in pfs ) is soldered to that and will transport the rf to the parallel tank crcuit. Cathodes are both grounded anyway so that is nothing new. One grid is a crystal oscillator. I found in my junk box a 28.76 crystal and built the normal crystal osc circuit on that side of the tube. On the other side I built  an audio amp circuit with a .01 cap for input from the mic. See mic jack in photo. (RCA phono jack) Will it work? I suspect so but may take a bit of rubbing. It only took a few minutes to build so if it is a wash nothing lost. I built it for ten Meters since when it is open you can be heard around the world in a whisper. If all goes well I will make the output coil / cap circuit in the morning and fire it up. I also need to find a compatible mic but I have several options.
We shall see tomorrow.
Don

"  I seem to be obsessed wih low and medium power AM "

Don, there is help. You just have to reach out and ask fer it.

It has been said that " it is better to put fire in the wire, than to curse with QRP."

We are here to help.

klc

If a tree falls in the forest ....

But is is fun. And a challenge too. I just love it!
Tank is made and hooked up. Fixed cap with accordian coil for now. GDPer says 28.7mcs right now so I should be able to find a sweet spot. Also almost forgot I have to make an RFC for the plate lead before fire up. I do appreciate the hi power stuff but it is a bit out of my league these days. I like to see if I had nothing what could I make that would work and how well would it work. I peaked I think when I made the POW radio in a birdhouse. I made a variable cap from soup can lids and some brass bolts removed from old furniture. Pie plate and paper with thumb tacks  for grid leak cap and thumb tacks and pencil lead on the wood for gridleak resistor. Stole 20 inches of house wiring (live) when XYL wanted a switch in the kitchen moved . That became the coil (hartley circuit centre tapped.) Some old fine wire from a  discarded part wound around a broken pencil became the RFC Found a discarded 52 tube and handmade a wooden socket. Powered it up with discarded batteries left for dead. Since I had no regen control just kept adding batteries till I heard a hiss. First station recved was a  Broadcaster broadcasting a piano recital from Barcelona Spain. Had the camera going and between my ear and the broken earphone my friend found at the dump so you can hear its first breath on You tube. Might not turn your crank but it sure was exciting for me. The hartley regen of course is just a hartley transmitter with not enuf power to quite oscillate and a set of phones (in this case just one ear piece) in the power circuit sensing the varying load. After assuing that it worked everytime I tried it I dug up some good batteries and raised the voltage to above 108 (11 nine volts )and tried it on tx on Cw . Worked fine. Pretty stable too.
That was a real fun project and it is sitting just to my right behind me right now.
I guess everyone has their favourites. This one I dont know if it will work or not but for the time spent it is worth it to me to find out. Cost so far? Zilch!
Don VE3LYX

Wellll, it could be worse. You didn't build anything in a tuna can.... or have u ??????


klc

I do have the one built with a half dozen radio shack Rf chokes and three transistors or so. Still works too. Best low power rig is my TTL chip crystal osc. I use it for spotting the regen when using it for QSOs then pop the crystal back in the front of the 50l6 bare essentails transmitter.(EI 1970)
I had my 1920s style TNT rig on just now. (7110 kcs)Big 45 tube with 13 watts in. the soft orange glow of the twin heaters, the hum from the PS transformers as you key. The bright flash of the Rf indicator lamp and loop mounted just close to the huge copper tank coil and the big 1920 variable cap with its matching knob. Whats not to like?
The 12ax7 does not want to run. I know it is something stupid I did but so far I havent found it. Should have done all this as a teenager back when I knew everything. My mortality is catching up with me I fear.
Don

 I know it is something stupid
;.) Apparently you have to put the monitoring revcr on the proper band. Who knew?
Anyway it works. Pretty good for a first try. The 10 m crystal was no good. IT wouldnt go in my test osc either so I quickly just built a 20M hartley tank for it . Got it on 14.2 right now. First I tried the osc. Strong steady signal . Not scary but surprising. Got that deep sound , "definate" I would say. Then I killed power and clip-leaded a set of 2000 ohm phones (aka dual dynamic mics) to the phono jack. Fired it back up to ear deafening feedback. Phones were facing the monitoring recvr a few feet away. Phone cord bothers the osc as do my hands . I will have to RFC that side I guess. So what is the point of all this? Maybe a pair of 811s on Am with no mod transformer. Cathodes grounded and plates tied together. One Rf one AF. Why? Because I have built several successful projects with audio and Rf in the same tube. Some pentagrid converters and some dual triodes. One even is a osc in one section and mic amp in the other. They work fine so this was a logical step for me anyway to try. 
Actually I have a dual 6L6 RF PA (parallel pair ) and could just unhook one control grid and try modulating it. At the very least it is intriqing to me.
I have a portable 12ax7 Am rig (rx tx)planned to build in a file box so this stuff is not wasted.
Don

Further test. Today while in the shack I swapped the 2000 ohms phones I had for a mic for an 8 ohm speaker sitting there with a plug. I fired up the little rig and turned on the monitor recvr. It came to life on the exact same spot. (always good!) I dropped something on the bench on my way back to the stool and heard it plainly in the speaker of the monitor recvr. I decided it must be a microphonic tube. But it isnt. The dumb thing actually works. Right now it is a "dead bug build" just lying on the bench, no chassis, nothing monted but it works. The voice is low or very bassy but I think that is just a matter of microphone match. Been down that road before with the mixer tube (6sa7)set. So I am going to build it in its proper box and continue development. I may even try a real proper microphone. Rig was behaving properly on this mic setup. No trouble with the hand cap thing.
Don VE3LYX

Hey Don

How did those caps work out for yur HV PS deal. I picked up a whack of 2E26 tubes the other week. The guy was going to throw them out. Most are still in the box. I know some guys don't like them or the 6146 for audio werk..and I know there are better tubes to use, if you have them....but I have these now. A pair in AB1 with a good match to the mod transfomer should work FB, if it was all designed correctly. A pair of 2E26s were used as a cathode follower audio driver in the BTA1R broadcast tx.

Al VE3AJM

I have the big supply going but I discoveredwith my PW AM rig it is not more power I need out but more drive in. For the extra voltage I didnt get a huge gain so I went back to what I had before. I am putting out near as I can tell close to 15 watts. That should be enuf for a QSO with somebody. It is a lot more then I had when I first talked to Tim on 40M a year ago. Now he could just tell I was there and we did do a bit but for this rig that is a long haul. Accross the lake to Rochester would probably be more practical. I am not comfy with big voltage. Dont know why. I had a Viewstar (was Hammond) Linear years ago and simply did not like using it on slop bucket or CW.  The one tube linear I built is working so well I hate to push it into the danger zone. My brother is down for a day or so. he is a Electronic tech and used to designing and using a radio range set up for EMI testing. I asked him if he was up for some extensive Field strength testing. He said he would if we can find a good time. I guess that is what iIneed.. Someone a mile or so away to monitor and make sure I am on freq I think I am, I have sufficient modulation to be heard beyond the barnyard fence and my antennas are working as I think they are. Hard to verify this by yourself.
Meanwhile back in the shack downstairs the 12ax7 rig is going into its chassis and box. This afternoon I tuned it up on 10 m for a test. Still works So it is time to carry on. It is going into a card file box about 7x7 inches with a folding lid. there will be a 12ax7 regen on the other side of the chassis and a vibrator /110 supply with a voltage doubler for the tx in the lid. Now I have to find  small but reliable 110/12 volt transformer.  This rig has more output then my PW Am rig so I can use it portable from the car battery etc or plug it in to the wall socket and pump it thru the 6293 linear. Since it has a lot more drive it should make decent power that way. Once I have the tx firmly mounted I can continue rubbing on it till I get it where I want. Till tonite it was just lying on the bench dead bug style with nothing fastened down. It will tune from 20 to 10 M easily. I may install a low value variable and switch some padders in and out to get 10 15 and 20M on the same coil. 
Don

12ax7 Am transmitter is now installed in the small file box. Transmitter is essentially complete and is on the left.  Mic goes in the jack . Antenna now uses the RCA phono jack (as does my DX60b)
On the right the 12ax7 regen is underway. Both circuits are very close as in both are hartley based so coils are indentical. Rx will tune through continuosly while Tx will be switched from band to band and will only have a portion of the band available so as to make accidental out of band operation impossible. Switch in empty hole at top will switch both antenna from RX to TX and B plus from RX to TX. (dpdt)
Same tube so mixup is impossible. Centre control is regen control . Phones of course go in the right hand jack. 12V vibrator power supply I hope will go in the lid.
Don VE3LYX
Going to finallize transmitter and test it this afternoon . I  may just leave it as a mono band unit. No point in overcomplicating a simple rig. I think i will tune everything to 28mcs  just above the code portion.

Padded the tank into middle of 10M . It cannot reach either end which is fine by me content in the knowledge I will always be in band. I checked the rx tank as well and it is compatable BUT I am not happy with its tuning cap. It should be identical to the tx and also have limited tunng range. One of the best ways to insure a regen works good is to set it up for a specific freq plus or minus a bit so you can float around the band a bit but limited. Then you can optimze it and it will do a fantastic job, even often putting modern Rxs to shame. Here it is already to go transmitting wise. HB mic started with a lamp fixture from Home Depot. Is a good mic and has press to talk as well. I fired it up on my vibrator PS liberated from a 56 Ford radio.  It is actually quite happy on that. I use a gel cell , sometimes two (paralel) to run it. Chassis is fastened in now . Rx is about 20% done. TX is 100% done.
Don VE3LYX

Fired up on 10M today 28.900 , Receiver almost done. Needs a switch and an INSULATED phone jack.
Soon
Don VE3LYX
ALL in the box and it still works! 10PM Sat

Wondering what happened Sunday morning Don. I could hear you abt S8 with relatively good modulation, and then you never came back? Hope that tx is limited to one transmission every hour or something??lol  ??? ??? ;)

Al VE3AJM

Conditions here were impossible. I could just hear Tim as a whisper and while I could hear you it was barely readable. Unusual for here as normally I hear you both well. Dont have a lot of time Sunday mornings anyway so when it was so tuff I pulled the switch. So you were in Belleville and Trenton last week. A email warning would at the very least get you a Timmy Hos. If you are ever sent accross the bay to beautiful Downtown Ameliasburgh stop by 310 Cty Rd 19.
Don VE3LYX
Working further on the 10M rig today. Decided to forget the insulated phone jack and put the phones in for the Audio Amp cathode resistance. Phones dont care where they go as long as they can feel the load variations. Also experimenting with different mic inputs.  (Impedances) I think the silly little thing may actually work ok .
Don

It was snowing on and off here on Sun. morning, and very windy but I didn't have any trouble copying here. I was to be in Havelock and Madoc today, but things were changed. Next time I'm out that way, I may look you up Don.

I just had a look at where you're located, so now I know. There used to be another Am'er from down that way..I know this name was Gordon and he was in Carrying Place. He was a regular on 40m AM in the 90s.
I think his call was VE3ASD. I think hes SK now though.

Al VE3AJM