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RCA Transmitter

F

Field_strength

I might start doing some work for a radio station with an RCA BTF-20E1 20kW FM tube transmitter.

Is this a fairly reliable transmitter? Are parts and service still readily available? Does RCA even make transmitters anymore?

Anything you can tell me about this transmitter make/model would be helpful.

Thanks in advance.

FS
 
I have one here as a backup runs ok.
here are some things to note, neutralize as best you can and keep those big resistors with the "antennas" on them in the PA cavity clean and check the value of the resistor, if they fail the PA will catch on fire!!!

those clock motor timers for plate delay can get stuck and cause it not to come on.
fil. wires burn up
also,the grid coupling caps can break due to stress put on them by the grid inductor.

Pete
 
I have had people refer to them as "the fireball". I still have two of them in service (main and an aux) and had a flame shoot out of the one on me when I first started working on it. Definably not my idea of a first impression!

RCA is non-existent nowadays but you can get some parts from two companies still. It does get really pricey at times as I found out one day when I needed to replace the multimeter switch. They are ok, but with their age comes more failures and lack of parts to repair.

One tip, keep them REALLY REALLY REALLY CLEAN INSIDE or you will be able to have a cookout!

Here are the two companies you can use for some parts:
http://www.rcatransmitters.com in NJ
Commercial Radio Company in Cavendish, Vermont
 
Ahhhhh! The BTF-20 Fireball Series, special edition! I had one that we had to totally take apart, clean and replate parts in one time because water got where it shouldn't have got. Honestly, I wished we could have collected insurance instead. LOL! RCA's slider inside that thing was a great source of failure in many of those rigs that were kept unclean for sure. For a backup rig it might be O.K., but basically I'd be pretty reluctant to put one of them on full-time in this day and age. There's better used stuff out there like an old collins or Continental, or the like if a person has a choice. The sheer fact parts aren't that available anymore for RCA junk basically tells me I'd rather not. They were squirly boxes from the beginning anyway. The tuning was fun on them too.. Narrowbanded tight-Q.. LOADS of fun!
 
Fireball is right.keep it extra clean or you'll find out.sure makes the old wooden xmtr shacks obsolete Ha.. That's why cinder block bldgs became so popular. field strength you will have fun...station went off air, by the time they got to the shack,it was burnt toast and cinders...
 
Ours won't make full power, no matter what we do, or how we tune it. It has flamed on us, as well.

It's used as a backup, not as a main. We've been lucky, in that we've barely had to run it when taking our main Continental offline for work.

...when someone is present.

Not fun to maintain, but look at it this way, if you're billing by the hour...it might keep you in shoes for awhile.

There's two ways to look at everything!
 
I was also taught that if you tuned these transmitters to any more than 65% efficiency the circulating currents in the PA cavity could cause them to start on fire. The chief I worked for back in the day saw one once that was burned with the meter in place pointing at 100% forward power. On the flip side, we had four BTF -20's that ran in combined pairs of alternate mains (as BTF-40's) for more than 30 years without any fires and little down time on either set. Parts availability became the biggest reason for replacement.
 
RCA stopped making these 25 years ago, just a few years before they went out of business. This product line came out in 1962 and remained the same with many modifications right up to the end of production. The ones that ran well were at locations where regular scheduled maintenance was conducted. Others that were not maintained usually suffered meltdowns in varying degrees. We had a binder book that contained all of the modifications over the years. It was thicker than the original manual and schematic. I would have serious concerns about any licensee who still operates one of these units as a main and concerns about using one as an alternate transmitter, given the current engineering staffing commitment of most broadcasters (or lack thereof). Ah but that is another topic…

Best,

w/
 
So I am curious... Is this what they "really" meant with that old term "blowtorch'?

:D

R
 
Been a while since I have posted, but the RCA caught my attention.
The BTF-20E had a deck made of the finest plexiglass Woolworths sold is was told. Here is a link to a fire in one. http://www.pbase.com/alwayssomewhere/image/62939921 If that does not work google btf 20e fire. Had one burst into flames once, and once the plexiglass gets started better get ready to run, since it is hard to open the cavety door to put it out! Be careful..verry careful.

Lane
 
jboydingram said:
You do not want to maintain this unit.....TNX....JBI
Click to expand...

If you don't think the above were the wisest words ever posted on this site, take another look at the link to the above mentioned fire picture. It's a miracle the room survived.
 
With such a fine tranmitter being one of their premier boxes in their line of fine products, there's no doubt in my mind why RCA isn't in the transmitter business anymore. Yugo quality at Mercedes (original MSRP) prices! What a deal! It'll even toast your sandwiches for ya!

:D
 
So can any of you explain for those of us not in the know, why RCA transmitters caught fire so easily? I remember reading about a transmitter leaking oil, which caused a fire. But I've seen posts here stating even dirt would do it.

Also, was RCA the only transmitter that could catch fire so easily? Or are there others?

Intereesting thread, and scarry pictures :eek:

Thanks for sharing :)

R
 
Lane Lindstrom said:
Been a while since I have posted, but the RCA caught my attention.
The BTF-20E had a deck made of the finest plexiglass Woolworths sold is was told. Here is a link to a fire in one. http://www.pbase.com/alwayssomewhere/image/62939921 If that does not work google btf 20e fire. Had one burst into flames once, and once the plexiglass gets started better get ready to run, since it is hard to open the cavety door to put it out! Be careful..verry careful.

Lane
Click to expand...

The BOLD lines offer some insight into that subject.
 
To be fair, RCA made some workhorse AM transmitters, and some early TV transmitters that were dependable (with apologies for the water cooled system).
As for the FM series, I never really cared for them, especially the late ones under discussion here.
AND, regardless of the unit you had, you probably bought it agin in parts prices!
Thanks...JBI
 
Yes, I am from Mississippi...but I know agin is really again...believe it or not!
Thanks all, and this is a good list, in my opinion....JBI
 
Most of the btf 20s I've seen were the 'deal sweetener' fior a TV transmitter. They worked OK in an attended plant where someone was always there watching; and you reworked the socket a couple of times a year. At 65 - 68 % efficiency on a good day, they got beucoup hot. Which made everything in them tarnish quickly and begin to get even hotter. Coupled with the (Moseley - built ) black front exciter, the box was a completely underwhelming radio.
 
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