I may be getting an RCA BTA-1R

[VE1IDX]

Dispite having been in the radio business as a station engineer for 22 years I have NO knowledge about the RCA line of transmitters. All my experiance has been with the Gates BC1 series and some Harris stuff as well as the solid state Nautels.One of my former co-workers at a sister station in PEI (VY2 land) has offered me a working RCA 1 Kw broadcast TX.He forgot the model number but it sounds very much like the BTA-1R with a pair of 4-400's modulated by another pair of 4-400's.He is to confirm this with me in a few days or so.All I have to do is drive the 650 miles round trip to pick it up. Has anybody got experiance in converting one of these to 80m? I was planning on building an amp this winter to use along with my DX-60B transmitter and Kenwood TS-820S as well but do not have the tubes sorted out yet.I was leaning towards a quad of 572B's.Would it be worth my while in trying to convert this TX to 80m or should I scrap it out and build a nice amp from it that would surely see more use than a single frequency TX? Walter says he has lots of spare 4-400's and thinks four of them may be brand new.Perhaps I could come up with some sort of VFO control for it.I am just batting around ideas at the moment but hope to pick it up the end of August.The wife really liked the idea of me scrapping it and selling what I don't need but I told her at some point in time I will need ALL the parts. So many ideas and so little room for them all.

[WA3VJB]

Fine Business on the BC rig.  The 4-400s lend themselves to multi-banding easier than the triodes of the BC-1.
Two people come to mind mmediately for technical advice -- Robert, WØVMC has pushed two examples of the 20V2 through 20 meters (same tube lineup), and Steve, N8JRJ has pushed a BTA-1 through 40 meters.

Tim, WA1HLR has pushed a 20V through 40M but said the biggest challenge is the oscillator/driver stage. You may have less trouble coming in later with that Kenwood as VFO/excier.

Two RCA models used the 4-400, the BTA-1R and the  1S. They're quite different cosmetically.
Check out the books at:

http://sujan.hallikainen.org/BroadcastHistory/index.php/RCA

[WD8BIL]

Paul, N8JRJ is now KJ8CQ !

[Ed-VA3ES]

Over the last year, Electric Radio has had a series on BC rigs, including the BTA1-R1. The series details the mods and ham-banding schemes.

There are several hams who have successfully modified the BTA1R1, including N2BC and possibly KJ8CQ.  He's posted a reference to this on this forum; (unfortunately, I  can't find that post).  I would do a search of "BTA1R" on this forum to find all references to that rig.  I own both a BTA1R3 and a BTA1S.

[VE1IDX]

Well after further fact finding it would appear that the TX is a BTA-1S not a BTA-1R.That is fine as it means a smaller footprint.I have found a full manual online for the R model but all I can find for the S model is a sales brochure.I will get the manual when I pick the TX up the end of the month but would like to have a peak at one before then (read excitment) .Anybody able to point me to an online source for one?I would expect the actual circuit is very similar with a few upgrades over the R series.

[Ed-VA3ES]

Give me ur snail mail address, and I'll get my BTA1S manual copied for you. (Cost should be abt $10. or so.)  The BTA1S is indeed a  smaller footprint -  the rack is actually a 19" rack, and can be easily dismantled for moving.  It's also only 6'6" high, so the TX will fit in places where the BTA1R won't.   Yes, the schematic is very similar to the BTA1R series. It's almost identical to my BTA1R3.
You can look-up my info on QRZ.com.

Nice find! 

[WA3VJB]

Another station who has successfully converted the BTA-1 through 75 meters is Roger, KC8OPP at Medina, Ohio.

I worked him using that transmitter on First Wednesday AM Night around 7:15P last night, 3885Kc.

I'm sure he'd be open to a chat.

[KC8OPP]

Paul

Good to hear ya last night, been a while.  The RCA BTA 1R here does 160/75/40M.  It is just parked on 75 for the time being.

Garth, good luck with the RCA.  If it is close to the 1R I will try to help as much as possible.

73's
Roger
KC8OPP

[VE1IDX]

Tnx for the offers guys.I will be looking for some info after I get the beast installed in a corner of my basement.As it happens the best place for it is right along side my electrical panel and about eight feet from where my antenna cables terminate before going upstairs to the shack.

Roger,you have a band switched BTA-1R for 160/80/40m? Was it much of a problem and does it operate on a fixed freq on each band or do you have some sort of VFO control? I suppose 1885 and 3885 are the most desirable freqs. to use.Man this is going to be a long three weeks until I pick it up.

[KC8OPP]

Garth,

Yes the BTA 1R does 160/75/40M.  I use a Kenwood 520 for the exciter so any freq is possible.  I removed the xtal osc board and built an input circuit that fit in the panel cutouts.  The final tank uses the "L" coil from the orginal pi L tank.

For a few pics of the move and conversion look here,
http://photos.yahoo.com/kc8opp

Good luck with the project, I thnk you will have fun.

73's
Roger
KC8OPP

[Mike/W8BAC]

Roger,

What is a UPM-17? That boat anchor in one of the photo albums. Nice job with the 2" hard line! That was a job.

Mike

[ve6pg]

...1885 IS A GUD CHOICE,AS WELL AS 3880-85...BUT DONT FERGET 3725..THERE IS A BUNCH OF AM OPERATORS THERE,HERE IN VE3,AS WELL AS VE2,VE1,VE9,AND SOMETIMES VY2...
...HELPED KEN,VE3MAW ON FRIDAY GET A "FTR501" OUTTA A BARN,NORTH OF TORONTO...4 4-400s....200BUX,AND HVY BEAST...REMOVED ALL THE IRON,AND GOT IT BACK TO KEN'S BASEMENT..CABINET WEIGHS ABT 250 LBS,ON IT'S OWN...THE DOOR WEIGHS ABT 60 LBS...WHOLE TRANSMITTER IS ABT 650 LBS...NICE RCAF TRANSMITTER...KEN NOW HAS 2,ONE WERKING IN THE UPSTAIRS SHACK,AND THIS ONE IN THE BASEMENT...AL,VE3AJM HAS 3,ALONG WITH HIS GPT750,AND OTHER HB RIGS...LISTEN FER US ON 3725...WE DO WERK U GUYS DOWN EAST...TIM...SK...

[VE1IDX]

FB on the FRT501. I am picking up my BTA-1S the end of the month and all it costs me is gas and grub and maybe a night on the road.I have sort of taken the summer off most activities but normally we work 3735 every Sunday morning at 1200Z.I have heard some VE3's on 3725 before.I think the best bet is to first make sure everything works on the broadcast freq it is tuned to and then start the mods.I intend to bypass the oscillator section and insert a low power driver from most likely my Kenwood TS-820S or possibly the DX-60B if I don't mind not having 160m..Maybe I'll even brew up a separate VFO for it.That will probably happen but not for a while and I expect to use an external driver like the Kenwood to start off with.I hope to have it running into an inverted L strung across the river behind the house this winter.The wire should be 55-60 feet high.I may have to replace the RG8X I am using on experimental antennas when I bring it online.I figure replace it before rather than pick up the pieces after.

[The Slab Bacon]

A BTA-1S will be a very interesting challenge to multi band. It was a cheapened /
competition model. I had one and decided to recycle it due to its poor design.

I would suggest converting it for 160, but not trying to multiband it. It has NO tuned circuits anywhere between the solid state crapstal oscilator and the final amplifier.
It relies on the final tank and low pass output filter to catch the crap that is generated other than the operating frequency. Trying to multiband it without the normal tuned circuits between the stages would be a very interesting challenge. Its pcboard construction in the lower level stages will be very difficult to find somewhere to install the necessary L/C networks for multibanding. I figgered that it would be less work to build something from scratch.

I figgered that it was too much like re-inventing the wheel, so I recycled mine for a
future LARGE homebrew project. the BTA-1S has some really nice iron in it! With a 100+ lb oil filled mod tranny and a 300lb Heising reactor, and a huge plate tranny, it is some really sweet stuff to get your hands on..

I will be curious if / how you multiband it. Inquiring minds want to know!

                                                               The Slab Bacon

[VE1IDX]

Well I first have to get the beast home into my basement and see just what I have to work with.Apparently the TX has not been used in years but did work the last time it was used.Don't ya just love being the next person to flip the big switch with a rig like that. What surprises lie waiting?I was thinking along the lines of an external frequency source such as my Kenwood TS-820 and inserting low level RF into the 6146 driver stage and rebuilding the output tank to a pi circuit with a tapped coil and variable caps.I'll need to look at signal levels out of the oscillator section and onwards through the chain.Be real sweet if I could use the transverter out port in place of the crystal oscillator.As a last resort I would scrape it and build that big amp I have been wanting to build.I can see four 4-400's in the final now.That should be good for our Canadian legal limit.

[WA3VJB]

Big AMP ?

I hope you mean a big Plate Modulated rig.

There's a guy on 75m who saved a KW-1 about 20 years ago from the same fate -- owner didn't think anyone would use it on AM anymore, so he was prepared to dismantle it and make a leen-yer out of it.

And Frank, looking forward to when you break ground on a Heavy Metal transmitter from the old "S".

[The Slab Bacon]

And Frank, looking forward to when you break ground on a Heavy Metal transmitter from the old "S".

Believe me, Paul, as long as I looked for and lusted after some big mod iron, that stuff will leave my posession "when they pry it from my cold, dead hands!!"

[VE1IDX]

Well as of noon Monday August 28 I will be on the road to pick up the TX.I was going to leave at 6:00am but as it would happen even though I am on vacation this week I have to write an exam at 9:00am for a job posting.    (The vehicle is all gassed up and loaded with far too many tools than I will need for the removal job but you can never be too prepared for the unknown I guess.I even have a stock of fresh batteries for the digital camera so I hope to post a few pix of the TX rescue.Walter told me they were just going to (gasp) throw it in the dump!  The company has no need whatsoever for a used 1 KW AM tx.Thanks go out again to Walter, VY2DU, for the offer.I'll let you guys know what I end up with after I get it home.

[WA3VJB]

Good luck with the move -- walk like an Egyptian, etc.

Suggestion to make sure your digital camera is on maximum resolution. Makes it publishable.

Can't wait to see, and get someone to snap your shot standing next to that critter !