Hi Garey,
My first reaction is, "Wow!" I was hoping there was already a muting
circuit, as with the TR7-R7 pairing, but in that case I doubt anyone
would use the TR7 as the receiver. I'll get my Service Manual out
and go from there.
Thanks much!
VY 73,
Tony
K4KYO
At 01:28 PM 2/23/2011, Garey Barrell wrote:
Tony -
I'm not aware of any external 'Standby' control for the TR-7 receiver.
A quick look at the schematic shows that the AF OUTPUT chip has it's
own +13.6 VDC source on Pin 30 of the 2nd IF/AF board. There is a
22 uF cap on the line, so the cut off 'might' be a little slow, but
it looks like you could just interrupt that supply and MUTE the receiver.
There may be another way to inhibit a part of the 10R bus, (the
'normal' standby internally is accomplished by turning off the
entire 10R bus,) so that could also be done by control on the
Transmit/Exciter board via Q307 and Q308. Grounding the Base of
Q308 would MUTE the receiver.
Unfortunately that is the inverse of Drake MUTE circuits which OPEN
a ground connection to MUTE the receiver, so an inverter stage would
be necessary. Still only a transistor/resistor to invert.
There are a few spare pins and at least one RCA jack on the back
panel that could be used.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Richard A. (Tony) Stalls wrote:
Hi guys,
This morning during my vintage AM net, my antenna changeover relay
decided to quit on me, so I switched on my TR7 to use as a receiver.
As there's no standby mode, before transmitting (100 watts) I
turned the RF and AF gain all the way down and manually switched
the antenna to the TR7 with the coax switch. It didn't work so well though.
As I often have both rigs on at a time, it would be nice to be able
to mute the ones not in use rather than turn them off, especially
those that need to stay warm. I've looked through the TR7 manual,
but I can't seem to find anything on a standby mode. Does anybody
know of a way to use the TR7's receiver with another transmitter?
Thanks & 73,
Tony
K4KYO
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