Paul -
OK. The receiver MUST be in the EXT MUTE, NB or CAL to be muted by the transmitter. If you unplug
the MUTE cable at either end, with the receiver in any of those positions, the receiver should mute.
There should be NO idle current when the relay is de-energized. If you pull V11 does the idle
current drop to zero immediately?
If not, then there is a problem with either C60 feedthru or the wire that goes from the METER
terminal to the front of the rear section of the TRANSCEIVE switch. Make sure that the METER lugs
are not turned where they are shorting to the bracket or chassis.
The neon indicator in the T-4XB should be ON in either the SPOT or XMTR position and turn ON when in
transmit, OFF in receive.
The indicator in the R-4B is always ON when the FUNCTION switch is in ON, and in EXT MUTE, NB or CAL
is ON during receive and OFF in transmit.
The fact that the transmit light is ON at all times indicates that there IS short on that key line
described above, or the relay is NOT breaking contact when de-energized.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Paul Gerhardt wrote:
Garey
OK I did some more checks today and this is what I see. With the
Transceive in Separate and INJ cable hooked up I can hear the
Transmiter VFO in the Receiver and I can still adj the Idle current
(although the idle goes up another needle width when the relay closes)
I turned it over and tried poking the relay while in receive mode and
it did not change. I can hear it switching and seems to be working
but in Separate the xmit VFO is 'ON' and I can adj the level in the
receiver with the bias adj. I pulled V11 and it did not change. Will
check the T/R relay again and make shure someting is not stuck in the
contacts. I feel it is almost working but not yet...
In Separate should both neon vfo lights be on all the time? I can't
remember but now I have the transmitter neon on ALL the time and the
rcvr neon goes OFF when I key the mic. In Rcvr AND Xmit Mode either
light stays on all the time. Should Both Neons alternate in Separate?
Paul -
Make sure that the TRANSCEIVE switch is in SEPARATE and the MODE switch
is in SSB. Are you SURE the relay is dropping out? If these are
correct, pull V11 out of the socket. A heater-cathode short in this
tube will keep the transmitter keyed.
Check the relay carefully. It is possible for the "Normally Closed"
contacts to be pressed down far enough to trap the "Arm" contact between
the NC and "Normally Open" contacts, keeping the receiver "On" even
though the relay is not energized.
A 150 ohm resistor at R3 will dissipate about 1.5 - 2W, which will make
the resistor quite warm. 2W of heat is 2W of heat, regardless of how
big the resistor is! A maximum of 18 VDC ACROSS R3 is within the
"normal" range.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com <http://www.k4oah.com/>
--
Paul Gerhardt
K3PG
http://pgerhardt.blogspot.com
QRP ARCI 6674
FP 274
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