The AM Forum

Been an SWL for many years, finally decided to get my license. Sat for the exams last Saturday (April 12 08, thank you Sunnyvale CA VEs for giving up a sunny weekend day to help mint some new hams). I was fortunate and passed Extra so here I am, AF6IM. My 18 year old son took the exam with me and got his Tech, KI6PQR.

I love AM and want to operate using that mode on HF. I have restored a few WW2 and postwar surplus rcvrs eg BC 348 and ARR 15. Thought it would be fun to operate a stock ART 13 which is a natural mate for either of those rcvrs. A ham friend suggests that I should consider a different choice since an unmodified ART 13 will never have a "good sound" due to audio bandwidth limitations and other factors. He suggested various Johnson models and other 1950s-early 60s ham xmtrs.

I have also always lusted after a Navy TCK 7 after seeing an NOS one at J&H Sales in San Carlos CA back in the 1960s. Wish I had bought it and stored it for this day. I know it needs a better modulation setup and would need mods, but it looked sooooo good. Is anyone running one of these? Wonder what happened to that new one I saw?

I know there are a lot of AM experts here so I am all ears. Please give me your suggestions for a first AM xmtr. Although I love the sound of the commercial BCB sets, the ones I could afford are probably just too big and heavy for my space.

Thanks in advance for your help. Hope to meet you on the air soon with a decent sounding AM signal.

73,
Mark
Palo Alto CA

A Heath DX-100.    Get it, do all the mods. You won't regret it.  125W output is a good start. You can work up your power later, when you homebrew your 813 rig!  ;)

Viking 2 is also a nice rig to play with.

  " to operate a stock ART 13 which is a natural mate for either of those rcvrs. A ham friend suggests that I should consider a different choice since an unmodified ART 13 will never have a "good sound" due to audio bandwidth limitations and other factors. "

You can improve the '13 audio with a few simple mods. Search here.

http://amfone.net/Amforum/index.php?topic=10889.0

lots a stuff fer  u to do


Like 'GFZ sez, the viking 2 is good, the viking ranger  is another fun one.....

klc

Hi Mark,

Welcome to AM.

Lots of good advice here. I'll add some more....


I have a plan for you to consider. If you follow through, you will save lots of time and progress quickly in technical expertise and making new friends.

1) Get on the air with anything you have now and start asking questions. You will start making AM friends right away and these guys will start opening doors to great deals and parts. You may luck out and find a mentor close by right away. Continue to ask questions on this forum.

2) Get a DX-100 or Viking 2 as a 100W starting rig to modify and learn from. You can still get killed on the voltages in there, but it's better to work your way up.  Do the mods and keep asking for advice from the guys on the air. Eventually you will hang with a group of like-minded hams who will become your "AM posse."   ;D

3) At the same time as doing everything above, start planning to build up a pair of 813's X 813's as shown in the link below.  This is a 400W (2KW pep) big rig. Start looking for the parts right away. There was someone on the air the other day asking if anyone needed 813 tubes. Look on eBay too. Within a few months you will have the parts you need.  As you learn from the mods with your smaller rigs, you will gain the confidence to progress to the bigger (and more dangerous, but strapping) 813 rig. Once you have built and tested your own "Big Rig, " you have arrived. In this hobby, there is a certain amount of respect given to those who have spun their own.  No one will know that rig better than you and it will be a breeze to fix and maintain.

http://www.amwindow.org/tech/htm/813/813.htm


4) Read the following article and the other ones posted in, "East Coast Sound:"
http://amfone.net/ECSound/K1JJ.htm

5) Buy yourself a good used ElectroVoice RE-20 mic with rubber mic stand/holder. Most hams buy 10-20 junk mics in their lifetimes. You  need only ONE good one to last forever. EV will repair it free for life. It is a BC standard and you'll save much time, money and aggrevation buying it right from the start.    

6) Start learning and practicing about audio processing AFTER you have a transparent, clean rig.  Get a 12 band (or more) audio equalizer to go with your RE-20.

7) Get up a 75M dipole as flat and high as possible.  Prefereably at 60' high. Coax or openwire is fine.

Follow these steps and you will succeed quickly in AM with minimum detours.

Best of luck and 73,

Tom, K1JJ

If you want an ART-13 to go with yer old buzzard mil receivers, why not?  Don't let the "it doesn't sound good" opinion scare you off.  It's YOU that oughta be happy with your xmitter!

Ben, n4ct?? i think is his call has two ART-13's completely gone through for sale.. One is a collins and more desirible. I ran one for years and wished I never gave it up. I had the BC-348 with it. I ran 572b's for modders at 1500vdc, 813 at 1700dc. A little tweeking on the audio as above and run a re-20 and eq. Your there. Only suggestion. BC-348 is for looks, pick-up a Hammerlund or AM receiver with good rejection and have a blast..

I have heard lots of ART 13's that sound OK. Down the road a piece Dean, WA1HSD has one running. That was back in our high school days in the 60's. I believe he did audio mods to get the rig to work with a regular dynamic mic. It made like 250 watts and sounded just fine. An ART13 is a really nice built radio that always attracts attention because we know what it takes to get one outta the dust and running again. PS, look at my DX-100 with afterburner mods for some more ideas. (Transmitter section)
Keith
WA1HZK

PS
Congrats & Welcome. We exist to keep each other talking.
AM is a way of life, not a hobby. (Timtron, a while back)

I agree with JN. If military is what turns you on, then grab some stuff and do it up right. always remember it's your gear. it should b hat turns you on as long as you have a decent signal and listenable audio.

Thanks to everyone for the thoughtful and helpful replies. Keep em coming. The warm welcome I am getting from the AM crowd is so encouraging and in sharp contrast to some hostility, aloofness and downright meanness I experienced from a few people on VHF when asking a few simple newbie questions. I am hangin with the right posse FOR SURE.

As you can see from my picture, I skydive. Been an active jumper since 1968. I am toying with the idea of doing what might be the first HF air to ground AM comm from under an open parachute canopy. Maybe they did it in WW2 but I havent heard about it. If I opened high, say 14,000 ft, had a really small batt powered QRP 75M xcvr, I could deploy a long long wire really easily. I'd have at least ten minutes for a few QSOs. Think it would work? Is there an available off the shelf SMALL QRP 75M rig? Dumb idea or fun idea? Could I expect some contacts with a QRP rig at high altitudes? If I had the "right" length could I get good radiation without a tuner with a very long vertical wire, actually sloped since the newer ram air canopies have about 20 kts of fwd speed.

Any leads on ART 13 stuff appreciated, xmtr, plugs, PS, etc.

73,
AF6IM

I like Gary's (kf9cm) simple ART-13 power supply.

http://www.kf9cm.com/schematics/image001.jpg

(Note that there is a short (extra line on the schematic) in the HV circuit.

Gary fixed the drawing, but there seems to be some kind of HTML page caching issue with the ISP so the version I get still shows the problem

Perhaps with a different browser you might be seeing a the fixed version.)

You will need the power connector, but they come up all the time on ebay. Not cheap, but at least they are available.

A Johnson Viking "I". the original, is also a good rig. The 4D32 final is unusual but fairly cheap.

I'm a young Old Timer (44 years old, and licensed for 30 years).  In my time as a ham, I've found the AM community be one of the most helpful and giving in ham radio.   These guys have all been a huge help to me with parts and advice.

As for a battery powered QRP AM rig - there are several options I know of, but I will tell you ahead of time, that they are not old buzzardly (if you want a vintage flavored ultra portable QRP AM rig, you're going to have to roll your own).  Here are your options:

1. Yaesu FT-817 - this is a 5W , all mode rig (yes it includes AM - but at maybe no more than 1 W of carrier power), that can be run with an internal battery pack.

2.  Yaesu FT-897D  - this is the higher powered big brother to the FT-817.  It also can be run off of an internal battery pack (which will give it 6W of carrier power).  This is the rig I used for a while last year, on AM.

3.  ICOM IC-703 or 703 Plus - it is a 10W radio (about 2.5W of carrier on AM), that can be run off of an external battery, or ICOM's accessory strap-on battery pack.  It's a cool little radio (I had one for about 2 years). 

3.  One of the milpack/manpack radios, like  PRC-113, PRC-350, PRC-1099, Vertex  VX-1200, or Vertex VX-1210 - these radios of course have internal batteries, and are carryable in a back pack.  They are very sturdy.  But there are a couple of downers about them. 

A.  Freq. tuning is a little clunky compared to your standard radio with it's main tuning/VFO knob.
B.  I don't know about the Vertexes, but most milpack radios run what's called AME (AM equivalent).  In other words they don't do full double sideband AM, their AM is basically SSB with a carrier.  It is copyable by an AM receiver, but the sound quality is typically mediocre.

73,
Ellen - AF9J

I have made a few AM contacts with my Yaesu FT-817. It is tiny and will operate for a while from an internal Nmh battery pack. Also, check out one of the tiny automatic antenna tuners that will tune a ~60 ft wire. Not sure how you could set up a counterpoise? ??? The antenna may need some study. At that altitude I would suspect you could make quite a few contacts. Let me know when you do this, I would like to try a contact from North Texas :).
73, Randy, W5KCM

errr.... I cant agree on the viking 1. it has some horrendous TVI issues, including a HUGE rf spur dead nutz on tv channel 6 hat also effects channel 7 to a degree. theres a cure though, included in the Viking 2 - a driver tube suppressor.

Great thread and great suggestions as I'm looking to get back on AM soon myself. I'd really would like to have a Johnson Ranger again (my rig in my General days- worked AM on 10 with it and CW everywhere else). Unfortunately I've grown accustomed to both arms and legs so the DX-100 is shaping up to be my second choice and a Viking II a very close third.

What about a "scratchy Apache"? Can the cap mods and such make it presentable on AM? There's one locally I have an eye on.

What about a Harvey-Wells TBS-50? Lower power but it is plate modulated.  Building an amp would be a project I'd enjoy anyways.

Barring any of those I could just go with my HT-37- not a true AM rig but possibly better than a ricebox.

Opinions & experiences welcomed.

As for skydiving on AM - just don't try it with the ART-13  ;D
 
73, Mark

The "scratchy apache" can be made to sound very good on AM. The mods are pretty simple. There are some good ones on Steve''s AM Window website. I built 6 of them for other people a few years ago and all of them turned out well.

                                                                The Slab Bacon

I remember reading years ago that when Doug DeMaw, W1FB (now an SK), lived in Michigan in the 50s or 60s, he homebrewed a 1W QRP, 160m AM transmitter.  He used it to operate aeronautical mobile with a trailing antenna from an old Piper taildragger (I'm not sure, but I think it was a Vagabond or a Super Cub). He made quite a few contacts with the QRP transmitter.  During the daylight hours, he used to be able to hold QSOs with stations up to 100 mies away from him, from the plane.

73,
Ellen - AF9J

Welcome to the AM crew!  I would also recommend a DX-100 or a Viking I or II as a starter AM transmitter.  All are good and will give you a decent sounding presence on the air.  As for the parachute mobile exercise, sounds like a neat idea, but be careful with that trailing wire antenna!  It would not be nice to drop it across a power line when coming down!  :o :)

73,  Jack, W9GT

Cool idea on the 75 meter parachute mobile. I used to fly jumpers for 4 years out here in central NY. At least one of them used to do HAHO jumps with his ICOM 2 meter HT and make QSO's on the way down, and I operate air mobile from my CGS Hawk Arrow with a Kenwood D7 slaved to a GPS, VC-H1, and a nose camera to send down SSTV pics of my view stamped with APRS, as well as voice ops.

I also plan to operate AM airmobile once I cure the ignition noise on the Rotax 582 and work out a safe way to trail a wire antenna without having potential for it getting tangled in the rear rudder or elevators. I've made some cool simplex contacts on VHF, though repeater operation is interesting because you tend to key up multiple machines.

Be sure whatever you decide to run is really well secured. My HT toting friend had the battery pack on his IC2AT snap off when his canopy opened and it made the 10,000 ft fall sans parachute. IIRC, he said it was pretty beat up after landing on the ground, but still slid on and ran the rig. And you don't want to cause any snags on a deploying chute, but then you know all that.

For my airmobile, I have a 36 foot aluminum structure in the wings, which should be a reasonable counterpoise for a trailing wire. On the chute, I'm not sure what would make most sense. I'm sure you'll make contacts if you just hang 66' of wire below you and feed it as a quarterwave worked against the minimal counterpoise of your body. Maybe a scaled up End Fed Par type antenna? Or a really huge J-pole?  ;D I'd start with a quarter wave end fed, you may find you never need more.

For HF mobile, I tried the 817 in the plane, but will probably go for something more QRO like an 857. But an 817 in a front chest pouch makes a pretty handy package, I use it on a bike all the time.

Good luck and keep us posted. This is a great gang to hang with and share ideas.

Tom, K1JJ, recommended an RE-20 for a mic.  While that's a good choice, an even better one would be the Heil PR-40 for a few less bux.  The PR-30 is even better for voice.

Scott Todd

I will have to look into that. No one has complained.. but they all have cable here.

Mark,
Congrat's on your new ticket.

I'm sure you'll enjoy the AM gang as well as we enjoy meeting new faces.

Looks like your getting about as many AM station recommendations as there are active AM'ers.  We sure love to tout our stations and equipment. Many of us have owned, used, traded, repaired and, yes, coveted all sorts of gear over the years.

Regardless of the higher priced or higher power stuff desired in the shack go with your heart at first.  If that's military, then go for it. As you operate you'll hear all sorts of signals from very weak (pw) to very strong (strapping, strappescent, etc.)   You'll hear (probably already have if you'd had a decent receiver as an SWL) all sorts of audio from "scratchy"" Apache to full commercial scrote."

The key to half of AM is in the receipton; make sure your listening to AM with a passband of at least 6kc; 8 or 9kc preferred during good propagation.  Then you will hear the full fidelity of East Coast  or similiar audio.  If your not already familiar, you'll learn about the diode pick-off trick feeding an outboard hi-fi amplifier and simple stuff like that for improved receiption; ... synchronous detectors and other schemes for more elaborate receiption. 

As the guys have mentioned, most all transmitters and receivers can be improved or modified in some way or other, operating ease, audio, outboarding of various components, full EQ, compresssion, effects, racks, etc.

Good luck with your aerial efforts. And if you decide on a trailing quarter wave, ...Yes, the end fed Zepp antenna sure has lots of history (Zepplin, H₂ hazard notwithstanding)  ;D

My vote for the best AM transmitter to own and modify is clearly the Johnson Valiant 2  not the 1.

Light weight aluminum chassis. Easier on back and table/floor.
Comes with 2,500 VDC Antenna loading caps.
Extra space to do necessary following;
Modify the pi-output bandswitch to handle more PeP.
Modify plate padders or better install larger C plate tuning cap.
Modify RF final neutralizing to work properly on all bands.
Relocate VFO screen grid dropping resistor and VR tube.
Re-shim/peg the 120 cycle, hummy power supply choke.

For good audio, strip the existing speech amp and audio driver Xfmr out.

Yes, I've been in most all Heath and Johnson transmitters and still fondle them occasionally.  73  John

I am looking at the schematics of the drivers for the I and II. The only difference I see is an added 0.005 capacitor and the replacement of the 100 ohm plate resistor with a RF choke. It seems that this would have more to do with keeping unwanted RF from the driver from getting into the 300V B+ line and the rest of the set. Is this all that is required, or was there a later factory modification that is not reflected in the manuals I have?

I have operated 10M AM from the Super cub and the c-172 whilst flying back and forth to Alaska using a base loaded 11 meter antenna hanging from the underside of the wing at the strut attach point....The transciever was a modified Sears Roebuck CB ..There used to be an outfit that  sold kits containing all the necessary parts and instructions for converting the uniden board based CB radios...I still have all the stuff, so if the sunspots come back I might get a chance to do it again.. 

Many CB stores still sell kits for "funny channels" on the CB that will get you to 10M. It's an inexpensive way to go.