The AM Forum

Good Day,

 I think a nerve was struck about this in another thread and there were some interesting posts regarding this. I am wondering this could cover alot of territory. The possibility exists of increased membership and a new direction...

 How bout Homebrewer's Corner. any thoughts....?


jack KA3ZLR.

 I found something that I thought that I would never see here in the 21st century!
Poking through the upset lid of a curbside trashcan, a fully intact chassis of an early 60's
TV set was spied. Complete and dust free! Sockets and resistors, capacitors too! A transformer bigger than a fist. How many rigs in the past were gleamed from such treasures? Maybe one in my future!

Greg, n1exi   

Well Greg my thinking is along the lines of the Regen guys and the PW guys and generating more interests in building helping others and maybe set up a net for this on the air.. I like the concept ...

maybe more input from others...?

My first homebrews were all built from TV parts I got from my boss at my after school job in a TV radio repair shop. 6DQ6 finals modulated by 6DQ5's ... using seperate power supplies made from TV xfmrs.

The best source of high quality parts I have had in recent years is old scrapped military equipment and surplus parts that most have no clue how to modify. Another windfall was buying the old percision custom design electronic equipment from Hanford Nuclear used in the 1950's. I salvaged Millen hardware, precision resistors, npo caps, etc. Don't over look old TV test equipment. Most of the old parts will out last us if used within parameters.

Yes I would like to see a homebrew board. Homebrewing was the start of AM-CW ham radio and if you build something that works, you appreciate it and have something of substance to talk about on the air.

My secret to successful complete station homebrewing is simplicity. All my audio is triode (pentodes wired as such if necessary), minimal controls, lots of meters to monitor voltage and current, use same power supply on class C RF and class B audio to eliminate extra screen power supplies, use xtal control (I do have a homebrew very stable VFO, but never use it anymore) and use in-rush current delay, no push to squawk (who in a hurry?) and for a receiver 7 tube dual conversion with NO BFO, a tunable IF the main knob, a volume control, a tunable 2nd osc to act as fine tuning and that is it ... 3 knobs. It is simple to operate works as good as any commercial dual conversion receiver only lacking in selectivity that the big dual conversion receiver now under construction will have.

The super regens are a great start. The 1950's and 60's ARRL handbooks have many good simple superhet receiver projects. Homebrewing is fun and rewarding. You can make it crude as my dad did using old metal anti freeze cans as chassics and end up with a receiver 3 foot long or use a nice bud cabinet and make it look professional. Any of you remember Fred with his transmitter built in an old refrig?

Like this my 813 amplifier, i'm going to post more in the pictures area.

Nice!

and understand something Sam, I'da never got this far without this Forum and the members that take part here, I'm coming back on the air as soon as the exciter is done.

I just checked out your QRZ profile Sam , Nice equipment!!

While tubes and similar widgets might be fun for some, many homebrewers also develop neat things with semiconductor devices. "Homebrew" covers lots of territory.

For sure. The future of homebrewing will be in software.

Ah, then we'll need a sub-topic under "homebrewing" for software bugs, firmware updates, etc. Got to have them bytes to sound good.

I don't know...

I don't mind homebrewing.  It's just that living in an apartment, it's almost impossible to make chassis and enclosures, much  keep things clean in the process (especially clean enough so that I don't end up with metal chips and stuff in the carpet that I or the cats end up walking on). It's fun for me to build stuff.  But building just for the fun of it  (which is also a common phenomenon in the expirimental/homebuilt aircraft movement) isn't my cup of tea I guess.  I've built QRP kits (and what what tiny little bit of scratch built stuff I've built), because I wanted something for a particular purpose.  When I built something just for the fun of building it (which was the case with several QRP rigs), it ended up sitting on the shelf gathering dust, taking up space I needed for other stuff.  I don't want to go there again.  I guess the way to go for me, would be like Don, K4KYV and some of the Class E & D guys - by building it, to have a (what would be for me) be-all and end-all piece of gear, that would always see use, either in it's present form, or due to continuous improvement to it.

Just my 2 cents worth,
Ellen - AF9J

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay001.jpg)

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay003.jpg)

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay005.jpg)

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay008.jpg)

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay007.jpg)

.....AWESUMMMMMMMMM


What is wrong with a section dedicated to this...look at the break down on that station

Most Excellent OM....

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay004.jpg)

Nice stuff Sam

Give us the run down

G

Thanks to Bob Heil for making these great vintage style mics.
(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/ebay009.jpg)

and what is wrong with a small section dedicated to this.....

Awesum Station....................

The big transmitter is a 813 class C RF at 300 watts out. It is modulated by a pair of 813's wired as triodes (Bill Orr handbooks have info) producing 500 watts peak in class B. I usually hold peaks to 125% positive.. The RF deck uses a swinging link isolated from plate dc by a 500 mmfd doorknob. I use a 6kv National cap for tuning. The grid circuit is link coupled to the exciter which is xtal controlled 6AG7 and 6146 final with pi network and 300vdc on plate and loaded light to drive grid at 22 mills needed for 125% positive modulation.

The audio driver is pair 1614's wired as triodes with 12AU7 driver transformer coupled and 12AX7 preamp. Impedance is high and an inline transformer is used to match low impedance Heils. The three pilot lights were to fill holes I drilled for tone controls that were eliminated due being no use as audio circuit is tailored for the Heil mics and needs no tone enhancing. I used red, white, and blue to add the good old USA look. LOL!

The small receiver is a broadcast band homebrew using 4 6.3v octal tubes in the traditional all American 5 design. It is 4 instead of 5 as the recitifier is a silicon diode.
The 75 meter convertor is an RF stage 6BZ6 and a mixer/osc 12AT7 and is peaked at 3860 but broadbanded enough that the entire phone band is covered without any noticable signal loss. The knob are main tuning, osc tweeking, and audio gain. The switch is xmit or rcv. I have it wired to the change over relay, so the swich stays in xmit.

The big rcvr (yes I know a paint job will help) is under construction and will be 80/40 meter bandswitched, a dual conversion with 3 IF stages, a noise limiter, two s meters, one on the RF stage, the other on the IF, and about 12 tubes unless I add a BFO which is not a consideration for now. The controls will be, main tuning (If tuning), audio gain, RF gain, bandswitch and RF stage peaking

Well, I don't think I will tackle a ribbon mic. I made a dynamic once that was ok, but Bob Heil convinced me his were superior in everyway.

Unfinished transmitter at right top shelf is a dual 807 modulated by 807's wired as triodes. I used 807's because I have several of them all unused in original military boxes. It has a self contained PS, exciter and audio driver. It is 160/80/40 plug in coils. I modified old Wilcox 99A coils for it. It will be xtal controlled or I can use my hb vfo when I find a cabinet for it. I took the cabinet for the small receiver. My antenna is an aborted off center zepp with the short leg grounded and about 21 feet high. The open line comes into shack were it matches 52 ohm coax almost perfect at 3860 and covers 3840 to 3900 with little swr.

Well, hope to see photos of your homebrew projects and hear them on the air.

I learned homebrewing from my dad, an avid homebrewer and kit builder. Most valuable were Bill Orr handbooks and close ham friends who are homebrewers and retired broadcast engineers. Thanks for your comments and opinions even if they differ from mine. We all have varied interest and mine is vintage style homebrewing ham gear and building triode audio amps for guitars, etc.

Thanks for the photos of the 813 amp and ribbon mic, very nicely done. What will you use to modulate the 813 amp? 811A's are nice, but I prefer triode wired 813's at zero bias. 73 sAM

Mack, the scope is the RCA bench scope WO-33A ... I have 3 of the little guys and a new crt for them. I am planning to homebrew a monitor scope some day. My only gripe about the 33a is they fade out if left on long. I have been meaning to go in and beef up the cathode resistor.

 I'll tell ya Sam i'm not sure which way i'm gona go this time, I left HF some years ago sold alot of stuff off and moved up in frequency into Microwave and uhf and was doing some things there with a gud friend of mine and his name is jack too I did put together a Motorola DSP system last year for 160 SSB, and worked the guys on the 1721 group that moved down there i picked those chips up on ebay and the tech i bought them off of gave me the coding for them it was a closed binary system but it worked off an old HP lap top in DOS and had a ball last season with them guys on 1872.

 So i am just coming back in here, been off the board for awhile, and one day just got the urge and signed back up, so you and i are the newbies i guess... but Hey you rocked the system here...You have a beauty of a station there...Fine Buisness Old Man...

over to you om...

Mine uses a pair of HF-300 triodes in pushpull, modulated by a pair of 810's in class-B.  My first high power modulator in the late 60's used triode connected 813's.

I use a dual 240 pf 7000 volt plate tuning cap, that I re-assembled with parts from three EF Johnson air variables.  I don't isolate my tank coil from DC.  The tank coil and split stator capacitor are all at full modulated HV DC potential, mounted on standoff insulators, with an insulated shaft coupling to the control dial. 

Series fed DC eliminates the big RF plate chokes, which are always prone to give trouble.  The plates of the tubes are series fed through the tank coil.  The only  rf choke is a small beehive 2.5 mHy choke rated at about 600 MA, used to feed the HV to the the midtap of the tank coil where the rf potential is at a minimum.  Even though the full modulated HV appears between the main tank coil and the swinging link, in the 35 years since I first built the transmitter I have never seen it arc over.  If it did, it would simply cause the overload relay to kick out before any damage was done.  However, I wouldn't recommend placing one hand on the transmitter cabinet while touching the ungrounded rf output line to the antenna tuner while the HV is on.  That's a moot point right now, because that line from the link is grounded on one side using the present coupling system.

http://amfone.net/Gallery2/v/stations/k4kyv/IMAG0016.JPG.html

my swingin link HB rig also used full b+ through the output coil. never a problem. Notice complete and utter lack of safety shield, etc.etc.  :-\

awesome rigs guys and nice engineering. I used the 3x 813 with the dc fed thru a Wilcox 99A choke (same as Art 13) to center tap coil for several years with 125% positive modulation, but when I got the Heil mic I increased the positive modulation over 125% and experienced occasional arcing as the ac component is increased, so I went with the dc blocking cap and changed out the old Hammurlund caps with unused Nationals. I tune with a dual 50mmfd and have an identical cap mounted on top as a trimmer. Makes tuning smoother and I can keep resonance about half capacitance.

The original set up used doorknobs instead of insulators for mounting the tuning cap and thus a short RF path to gnd and neat look. I thought I was original and then I saw this used in the Bill Orr Handbook. With the current set up the cap is grounded. I will try and find the photos of the inside before and after I have on CD somwhere. I built this rig in 1999.

Hey Don do you remember the SPAM group before AMI? I am looking forward to working you sometime ... I hate to mention this but you look at lot like me ... lol ...

Slopbuckets ?... lol ... you must have known Ricardo.

Here is something I wrote in the early 90's.

ODE to AM

In days of old
When hams were bold
and sideband wasn't invented

We tuned our load to the center of the mode
and talked away very contented!

I knew Hoisy, W4CJL (SK), the founder of the original SPAM, personally.  He later turned it over to Floyd Dunlap WA5TWF who unexpectedly went SK a few years later. A dude in CA (can't remember his name/callsign off the top of my head) took over from Floyd.  He was a real  flash in a pan.  He hit the ground running, but shortly thereafter he just vanished off the  face of the earth and took SPAM with him.  As far as I know no-one has ever heard from him since.


I still have the "I hate slopbuckets" T-shirt that Ricardo sent me.  He is not the originator of the term, though.  It has been around since the 50's.

Don, Have you ever experiemented with Taylor modulation?

Nice looking rigs Mack! Hey no problem for me to strip a Collins out. Stripped an ART-13 once for homebrew parts. If the parts are worth more than the rig, I will strip it before I sell it cheap and buy the parts from someones else for more money. I have stripped Johnson and Heathkit transmitters, National, Hammurland, and Collins receivers and lots of military stuff. The military gear really has some high quality parts.

(http://)(http://i231.photobucket.com/albums/ee264/W7XXX/audio2_edited-3.jpg)

Here is an exceptionally beautiful example of a recently completed (by KC9KEP) 1941 ARRL Handbook (pp117-121) superhet/regen receiver. Full details here:

http://antiqueradios.com/forums/viewtopic.php?t=79737

shhaazzzAM!!

Absolutely gorgeous.
If I didn't see the logo I'd swear it was a commercial product.  Maybe you ought to go into production.  Today's prices for components (of the obtanium variaty) probably $500.

(http://home.earthlink.net/~kx4r/sitebuildercontent/sitebuilderpictures/clydesrig.jpg)

Don, is that photo of a real rig???   talk about a breadboard!!! 

I'd be afraid I'd find the B+ with some part of the anatomy...

Yes.  This "bookshelf transmitter" is the handy-work of Clyde K4UXK of Columbia Tn.  A single 833 modulated by a pair of 833's. One of the better sounding homebrew AM rigs on 75 and 160.

My Grandfather's KW rig (W8YNG, father of W2DU) used this technique of mounting the plate capacitor for a pair of push-pull 250-TH's.  He purchased this rig used in 1937, so the method may even pre-date Bill Orr's writings.  I have just finished restoring this final, and hope to have it on 40 meter AM in the near future.  I also restored my dad's (W2DU) push-pull 304TL final and will have that on 75 meter AM.  (This was the rig he had on AM in the 70's, when Bacon suggested he swap the modulator grid caps to get more upward modulation!)  I still have lots of work to do on the power supplies and audio chain, so it will be a while before I have anything more than the 32V2 operational.

That is awesome Rick! Can't wait to hear this piece of history on the air again. That's cool you have your father's original call.

Now that is cool your GF's rig. I wonder if he ever ran spark?.....I have my GF's fig tree, pick ax.......and his desk light.....

Steve, when I upgraded to Extra, I debated whether to apply for my grandfather's or dad's call.  I decided on W8KHK, and I tried to keep it quiet.  I was to meet dad at the Dayton Hamvention, and the plan was to get a hat with my new call, and see how long it took him to notice.  But he was perusing the web and discovered I had the call a week before Dayton!

I posted a couple pics, the first one shows the W8YNG rig on the left, with the aluminum panels.  To the right is the black wrinkle p-p 304TL rig dad built in our Cranbury NJ apartment when I was between 1 and 2 years old.  

The second photo is a back view of the restored 304TL final, taken in my back yard in Marietta, Ga.   Hope to have it on the air soon!

No, Frank, he was not on spark, to the best of my knowledge.  Although my gradfather taught my dad how to build a one-tube regen receiver, dad actually got his ham ticket first, in '34. grandfather got his a few years later.  I do remember my grandfather gave me a Wen soldering gun when I was 5, and I built a three tube amplifier (5Y3, 6J5, 6K6) when I was 6. Been homebrewing ever since.  After I get the 75 and 40 rigs on AM, I will then work on getting the RCA BTA1-MX I purchased from Tim (WD4TC) up on 160.  So many projects, so little time!!!!