Total posts : 45366
Thanks for the words. I am really looking forward
to the return of the RC-6A. As mentioned, my good
friend didn’t have time to work on it.
We do know that the unit needs crystals that are fundamental
ones for the operating frequency. I do have a crystal for 860 kHz,
(it actually says 860 kC on it) but it is a very bad channel.
There is a station on 840 3 miles away, and on 880 is WCBS in
New York, which is a very good all news station. Even though they
are 100 miles away – we listen to them quite a bit because there is
no all news station locally. 860 is absolutely swamped at night by
a Canadian broadcaster. Even though they are French language, I
do stop on that channel at night sometimes and listen. Sometimes
they play some interesting music.
I had a crystal for 640. There was a time, as you know, when 640
was pretty much clear everywhere in the U.S. Unless you lived near
KFI in L.A., or near the few daytimers that were on 640 then, such
as WHLO in Akron, Ohio.
By the time I got the transmitter, 640’s clear channel status was
coming to an end. So that rock became useless pretty quick.
I had some oddball crystals for 921 and 944 kHz which worked
in the transmitter, but were useless because of the they were split
channels with other strong stations nearby.
My friend and I were thinking of ways to make the transmitter
better. There is no doubt it needs new 6AL11s. You can switch
the tubes around and the performance of the transmitter will vary.
But if the correct tubes are in the correct sockets, you will get
6 watts out with about 70 percent modulation. I hope getting
new tubes solves that problem and that the modulation will go
back to 100 percent. As far as I can tell, there is no hum on the
carrier. I think the power supply caps are OK. Maybe they were
replaced somewhere along the line. I am not capable of recapping
the unit myself so I hope that is still the same.
My friend was going to build a crystal oscillator that used a rock
that was 2 or 4 times the operating frequency. This would be
divided down to the desired operating frequency. Then he was going
to put some kind of small RF amp on it so it could drive the transmitter.
He was going to modify the existing crystal oscillator in the transmitter
so this would be possible. So, say – for instance – you wanted to go
on 530 kHz. You could use a 1060 rock, or 2120 kHz – that sort of
thing. He is more than capable of doing this. But he just doesn’t
appear to have the time. He is a great friend, and I know he would
do it if he could. Of course, this scheme would have been good, because
crystals that are over 1 MHz are less expensive than those that are below.
I have reason to believe that this particular RC-6A may only cover the low
end of the AM BCB. I say this because the two tuning adjustment coils (?)
on the inside seem to be near the end of their range. One of them is
really badly chewed up. To adjust this coil, you can’t use a screwdriver.
You have to use a pair of needle nose pliers very carefully.
So, I guess I already said this – but I plan to go with 1020 kHz, daytime
only. 1020 is empty during the day. WPHT in Philadelphia, PA pounds
in after dark. 1020 is as close to the low end of the AM band as I
can get for not much money. One of our friends here on the board
gave a cool link for inexpensive crystals that are below 1 MHz. However,
they are all for frequencies that are splits. 535 kHz is available, and
that is very tempting. It would work on all of the analog antique radios
in the house. You would not be able to try to track the coverage on a car radio,
I would love an elaborate carrier current system that covered a wide
area, but there isn’t two much I can do about that now. I will be
satisfied just to have the RC-6A running. This unit doesn’t not have
a tuning meter. But the neon light on the inside works fine.
All of my projects here are mainly on hold. The 13 MHz rig, the Gates board,
the solar repeater, and the new AM Part 15.219 outside set-up. I just
have too much going on. Every couple of weeks I’ll do a little bit with
something, but things are real slow.
Anyway, thanks for your information. I like talking about the RC-6A. It
must mean a lot to me, because, even though I have not been able to press
it into service, I have kept it all of this time. 25 – 30 years, something like that.
Bruce, DOGRADIO STUDIO 2