The AM Forum

At a celebration for my Dad'' 90th birthday he introduced his sons.  He introduced me as his #2 son who is a ham and builds a lot of his own stuff "but doesn't have the guts or where withall to find a RCAF AT3 or if he had to the GT3 Army version." Dad who was a Collins Radio (of Canada) aircraft radio design engineer (Avro Arro radios and the famous ARC552 where two of his "'babies") was during the war a wireless mechanic instructor at #1 Wireless School. He trained many on the operation and repair of the WW11 Aircraft radios and apparently this was his all time favourite. He said it never gave trouble and had a special start up sequence that if followed kept it from ever having trouble. This is not the first time he has told me to find one. I have no idea where to look or who might have one. Nor do I know what I am looking for. Any ideas?
Don

When it's cleaned up; it looks pretty neat.
http://www.google.com/imgres?imgurl=http://files.qrz.com/a/pt2ra/PT2RA_2012_VISTA_TX.jpg&imgrefurl=http://www.qrz.com/db/PT2RA&h=799&w=693&sz=100&tbnid=jHcTsoT-LrE0iM:&tbnh=107&tbnw=93&zoom=1&usg=__zYkmV9k6bxcozs6nOa0Al-VMD60=&docid=bZkFVfRVz1pSwM&sa=X&ei=yjSbUqziM4vhoATJyIFI&ved=0CE8Q9QEwBw

Good Luck trying to find one. Probably shows up at Estate sales priced way out of reality
Frd

Thanks, that is a monster! That is more radio then I want. I guess I will just have to remain Dad,s "disappointment".
I didn't realize it was that big.
Don

http://jproc.ca/rrp/at3.html

Another site with photo and description.  Also comments on a common failure mode in the tuning! (sorry).  :)

Don, I had been looking for an AT-3 for a number of years. We would often see components from the transmitter at the hamfests, especially the large edge wound roller inductors. There are a lot of guys up here looking for them of course. I found one 5 years ago. It is a heavy bugger, and I did get some help from Ken VE3MAW to get it, but I moved it here on my own.

Pair of 813s modulated by 805s. Good luck in your search.

Al VE3AJM

I have no good reason other than I always wanted some large WW2 Navy transmitter like the TDE or TCK to pair with my 1938 Navy HRO receiver. Have lots of other newer and better transmitters but just been wanting one for years. Did go as far as getting an old RCA MX and restoring that and have it operating on 1885 and that tends to waste massive amounts of floor space being it’s not just the transmitter but also a second rack with the GR 1931 modulation monitor and Voulmax and other assorted broadcast junk but now that they are all restored, converted and working have little interest in them, the big desire right now is something that’s huge, heavy and develops little power especially on AM
 

For me, the AT-3 transmitter is a relatively compact unit for its capabilities. We all can have differing views as to what constitutes monster or hulking in size for a transmitter.

It runs 300 watts plate modulated output on AM, and with small modification to its HV power supply, 500 watts of AM plate modulated.

It is a 2 channel transmitter from the master oscillator to the PA, continuous coverage from 160m to 20mcs. Its dimensions are approx. 68"H x 32" W x22" D. Weighs in at 630 lbs. Thats a relatively small footprint for my shack. Changing bands is very easy to do once each channel is set up properly.

I don't own a TCK or TDE transmitter, but from what I've read about them, their output on AM is only 100 watts and 30 watts respectively. So making reference to these transmitters and lumping them together with the AT-3 with regard to low AM power output, is confusing and makes no sense. You want to find a transmitter that's "huge, heavy and runs very little power output, especially on AM" What?? OK...knock yourself out on that one friend???

Its an iconic Canadian designed/manufactured transmitter, which played a big role in WW2 in France which my father in law participated/fought in, so this transmitter holds a special place for me. Besides, its a beautiful old buzzard AM transmitter that's very rare to find and put on the air 70+ years after they were made.

Al VE3AJM

Must be a Canadian thing, the TCK and TDE are poor performers in terms of power and epically the screen modulated AM but that makes me want one more. For years I have worked on broadcast transmitters and always held allegiance to Harris but in the last couple years and with installation of some of the new Nautel transmitters am starting to develop a likening for products from up north. And they come in wooden crates too.

I didn't realize you had one AL. It is Dad's all time favourite. In fact in his little speech Saturday he quoted the specs as you just gave them. I'll tell him you have one and maybe he will quit bugging me to get one. He said they are one well built tough transmitter. His exact words when he first told me were , "You need to find an AT3. THEN you would have a REAL transmitter."
Don

You have to like that sort of thing (a lot of weight for relatively little power out, and a piece of the past that is!).  Like driving around in a 1938 Buick, I suppose. Always wanted one, straight 8 and all, but unless I come into a whole lot of spare money I won't be getting one, and my newer car is much better in every respect from performance to comfort to safety.  It just doesn't "look" as cool  8)

It's that way with transmitters for me.  A new, properly engineered home brew is going to be a much better performer (and be a WHOLE lot lighter, I would think!) than anything old no matter what it is.  But, personally I like the "boatanchor" - old style rig look, so everything I build pretty much looks like a 1950s (or older!) piece of equipment.  People come to the shack and think everything is very old from the outside.  It's about as modern as can be on the inside.

If I were your dad, I'd sure be glad you have an interest in ham radio at all!  So many of the next generation don't.  For instance, one of my boys has his ham ticket, but at this time doesn't have any equipment or operate much (he's still in college).  My other son has no interest whatsoever in the hobby.  Both of them did follow my lead and go into high tech.

Hey, maybe your dad can use some of his contacts and find you one of those transmitters.  Make a heck of a birthday or Christmas present for you ;D

Well that's kinda harsh...
I have a working RAAF AR8/AT5 set.  Does that count?

Your Pop is a hard act to follow. You are, however, blessed.

Hi Don

Well, I will keep an eye/ear out for you if I happen to come across another AT-3. It modulates about 110% positive at 500 watts output on AM, and from the reports that I have received, its a good sounding transmitter. The weight or size of the transmitter is not an issue here.

My regards to your Dad. My father listens in to us on a HQ-180 receiver quite often. He is going to turn 91 in a couple of weeks.

Al VE3AJM

 Love the AR8/AT5 set up. Must be a lot of fun.  I have a pair of ARC5s for AM (and CW if I choose) Both are T18s but one I moved up to 80M and have had it on the air with Al even once or twice using my hb cathode modulator. The other is set up for 160M and uses the same modulator. I have yet to ever have a QSO of any kind on 160 , Am CW or SSB although I have the ability.
Al, I didn't realize it was that large. Dad didn't say . I think its a bit more then I am after. Anyway he sure loved it.
As for gifting me one? Not likely. Once he gave me a used floor sweeping diode so I could make a crystal set for my Christmas present.  I was kinda expected to carve my own way thru the world.  Tis neat Al, your Dad listening in. I had thought about getting Dad an old boat anchor to hear with but I am not sure he would. He did give me an HP freq counter and a HP DB meter when he sold his house.
As for RAF or RCAF  radios, I built a version of the T1154 transmitter from the simplified circuit used for training. It is basically just minus the second PT15 tube. The PT15 is designed specifically to be suppressor grid modulated. I haven't finished it but probably will this winter. It has that old world look. I started by finding and buying an NOS tube.
Don

If you build something well, the weight always goes way up, as does the size.
My big rig is in two 6 foot racks, and likely weighs 1200 pounds, maybe more.

Not all the rack space is used up, but it would never fit in one rack.

My smaller rigs are worse, 300 watts out in a 6 foot rack, with only one power supply...

Oversize everything and put in all the protetion and metering, and things will run forever.
The big rig has to be getting on 30 years old without a crapout...

Contrast a globe chump, 300 watts and none of them would still be working without a lot of work, and many don't even with a lot of work!
 

Ain't THAT the truth!  So much commercial amateur equipment (really, just about all of it except for maybe the KW1) is underbuilt, some more than others.  Most military equipment is better, and of course a properly built home brew transmitter can run almost forever.  The only parts that seem to wear out in otherwise good designs are tubes, relays (mechanical), switches and the like.

If you build it good enuf you will wear out before it does. (:>)
Don