开云体育

Barry,

To receive AM with the TR4 the Function switch must be set to "SSB"
not "X-AM". Setting the Function switch to "X-AM" will key up the
transmitter, disabling the receiver.

Operating AM with the TR4 is done as follows.

Tune the AM station until the receiving stations AM carrier beat note drops
to zero (no beat note heard). This leaves the AM audio heard in the speaker.

Transmitting AM, the Side Band switch MUST be set to "X" and the Function
switch is set to "X-AM".

Setting the Function switch to "X-AM", keys the transmitter producing
a low level of RF output carrier of approximately 8 to 10 watts.

As you speak into the microphone, the speech amplifier output is applied
to the CCSM Modulator V14 13DE7. The output of V14 varies at the same
rate at the speech amp audio, varying the level of screen voltage to the
final tubes, producing CCSM AM output ifrom the final amplifier.
You cannot switch side bands in X-AM mode. The side band switch must
remain in "X" for X-AM to work.

The microphone audio in X-AM mode is controlled by the XMTR GAIN control,
same as in normal SSB mode. Operating in X-AM mode there is NO AGC voltage
produced like in SSB Mode, to control the gain of the CCSM AM transmit signal.

To switch back to AM receive, the Function switch is set to "SSB".

To operate SSB or X-AM, the KEY socket MUST be shorted to ground. The KEY
socket is connected to the V4 transmit mixer's grid. Inserting a 1/4" mono plug
from a CW key or keyer into the KEY socket removes the ground, providing
a high negative grid block voltage to the grid of V4, biasing V4 to cut off. Shorting
the KEY socket to ground, reduces the grid block negative voltage to V4's grid turning
V4 ON. The KEY socket MUST be shorted to ground for SSB and X-AM to work.

This is covered in the TR4 manual.

73
Mike W5RKL