Garey was kind enough to send me a write-up from someone (no name on
it) who did an excellent job documenting it (with pictures). Too bad
I cannot find it on the web.
He had to notch the PCB with a Dremmel tool to get it to fit. I did
that as much as it would allow and it still would not fit. I had to
cut the half-box by removing the metal above the "window" on that
side. There was no other way.
Anyway, once the PCB fit, it was easy to solder it into place. Then I
made each connection, which was easier on my TR-3 because there is no
fuse bulb and RFC7 does not connect to the SO-239 on the early TR-3.
There is also a little choke to ground, RFC8, in the original relay
that is not re-used with the new relay. I don't understand why it was
needed before and why it is not needed with the new relay, but I put
it back. I could not hurt (I hope).
About the relays: I measured the resistance of the new 2.5K relay and
it is indeed 2.5K. I measured the old relay and it was 5K, not 15K
that I read about. I have another project TR-4 with the new relay,
and it has no added resistor (looked at the 6EV7 too). So I did not
add a resistor. The new relay works well and the TR-3 can hear and
transmit again. Yea! Well, sort of.
40M is a problem, and that is not uncommon on the TR-(any). I peaked
T-3 and it does receive on 40M, but it is clearly less sensitive. It
will not transmit at all on 40M. 15M is better, but still not good.
It's good on 80M, 20M, and 10M.
So now I have to figure out the mixer (suggestions welcome). But at
least the TR-3 lives again.
73,
Bob WW3QB
At 09:03 PM 1/1/2009, you wrote:
Happy New Year,
I have a project TR-3 too and it still had the original open relay.
It was a problem so I decided to replace it. I have the plug-in PCB
but I am having trouble physically installing it. It seems the half
box on my TR-3 is not long enough for the PCB. I need about 1/8 inch
more to line up with the connections. If looking from the back it is
the right side. So do I cut out that piece of the half box, leaving
only the back? Has anyone done this? It looks like the PCB will work otherwise.
The wiring is a little different than the TR-4 (no fuse bulb and
other changes), but I think I can figure that out (famous last
words). But not being able to even get the PCB in is a big problem.
73,
Bob WW3QB
John -
Drake sold a conversion kit for the TR series and the pre-C Line
T-4X transmitters. The early C-Line used a British made (Valpey)
plug-in relay that had a 15k coil impedance, and the wire was so
fine that is was either breaking from corrosion at the solder tabs
or mechanical stress caused by the heat variations. They changed
to a 2.5k relay, which was a drop-in replacement except for a 1.5k
/ 1W resistor in series with the coil. The added resistor is
sometimes installed across the socket for the 6EV7, between a blank
pin and the plate. I have the relay p/n, but not at hand. Someone
else has probably already sent it to you anyway. It's a current
P&B (TYCO) relay available from Mouser and others for about $16.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
John King wrote:
My TR 3 has been converted to the plug in type relay. Can anyone
tell me the manufacturer of the relay, its' part number, where I
can get it and the price? Thanks and 73, John, K5PGW
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
