The AM Forum

Hello All,

I'm interested in building a 100 watt AM and CW transmitter that would be approximately the equivalent of a Johnson Viking. I'm wondering if it would be possible to find new parts for the project from the usual suppliers like Mouser and RFparts, or are there "unobtaniums" at this late date. I don't have a junk box worth mentioning, and I'm not eager to go on a scavenger hunt, or take my chances with finding something on ebay.

I know that new modulation transformers are hard to find, but I think that there is a possibility that they are available from AnTek, perhaps on special order. High volltage variable caps don't seem to grow on trees either. Any other "gotchas" that would stop the project in its tracks?

Thanks,

Brian Burns...soon to be K6UCD once again

Brian,

You might consider buying a parts unit Viking 1 or 2 (or DX-100 or Apache) to get most of the parts since that will be far cheaper AND easier than trying to find all of the individual pieces.  You can find most of the small passive components you need from Mouser and others but not the RF pieces, big transformers, tube sockets, etc.

I can send you a scan of a Radio and TV News construction article from the 50s that has a homebrew transmitter that looks much like a Viking 1 design if you are interested.

Good luck with your project!

I would really appreciate having a scan of the article that you mention. My motivation for building my own is to have a unit with new reliable components. I've given some thought to simply re-building a Viking, but it just didn't seem as interesting as getting out the old chassis punch!

Cheers,

Brian

PS my email is listed--just click on my name if you want to send the scan as an attachment.

The new ER has a Viking 1.5 that is a HB version of a V-1 complete with parts list. The modulator article is next.

Carl

Yo Carl!

Fancy meeting you here! Now I'm really going to show that I'm still wet behind the ears--ER? A magazine?

Cheers,

Brian

ER >> http://www.ermag.com/index.cfm

Do you have any experience building transmitters?
QST and CQ Mags and ARRL Handbooks from the 50's and 60's had tons of homebrew transmitter articles. A basket case rig from a hamfest can provide many good hard to find parts. Trucking through all the parts suppliers to find all that you need (new) can be a very time-consuming process and probably not cheap.

Hello Pete,

Back in the day (1950's) I built as much transmitting and receiving equipment as a kid from the wrong side of the tracks could manage. I'm intrigued by the idea that it might be possible to build tube equipment with parts from the usual sources. I do my best to never leave the city limits of my small town of Fort Bragg CA, as it's a 250 mile round trip to anywhere else that there might be a hamfest or parts house.

So my question is about the availability of critical parts, as I don't want to spend a lot of time gathering the necessities, only to discover that a crammastrom for the kluge hasn't been available since Jimmy Carter was president. I like making stuff, and winding coils, and even making HV variable caps looks like it could be fun.

Cheers,

Brian

Welcome aboard Brian!

I'll put a stake in the ground and say 'Yes' you can buy the parts you need new.

Now, I can't guarantee that for a given 60 year old design that you will be able to find that special 'left handed, dual gang, contra-reverse audio taper, 26.5Ohm, wire wound, variable resistor' made only in Peoria by a disabled WWII vet from 1946-1952.

Still,  I'm sure that with some ingenuity and scrounging work arounds can be found.

If you want to build something from scratch, then do it.  Obviously, the fun is in the building.  If you want more predictability, then refurbish an old rig.

Either way, you are going to have to buy replacement parts from all the same sources!  The only difference is the amount of effort required!

Bill

Brian, with the Internet you never have to leave the house. There are many builders forums and even Fleabay has bargains if youre patient or are looking for something common.

Id also suggest you take the time to go to this one next week

http://www.w4bfb.org/hamfest2012/hamfest.html

and then this one

http://rars.org/hamfest/

Have fun

Carl

Yikes Carl!

Those hamfests are thousands of miles from here!

Or did you mean there is a way to go there on the internet?

Cheers,

Brian

Some sources:

Radio Daze
Antique Electronic Supply
Just Radios
Fair Radio Sales
Surplus Sales of Nebraska
SND Tube Sales
Allied Electronics
DigiKey
Mouser
Newark
Cardwell Condenser.com
Vacuum Tubes Inc.
Tubes_Tubes_Tubes
List of more suppliers:   http://www.antiqueradio.org/parts.htm

Hello Bill,

Thanks for all the sources! I really appreciate your taking the time.

While I'm in the thinking stages, is 100 watts out a realistic power level for AM these days, given a good antenna? Or should I be thinking of more? I have just enough room to hang a vertical two element Moxon for 40m.

Cheers,

Brian

don't forget: http://www.oldradioparts.com

They don't have the best search engine. You have to know what you're looking for.

I have bought many items from Gary at Old Radio Parts.  He is a real stand-up guy to deal with. :)

73DG

I got my Ft Braggs mixed up Brian!