Receiver signal loss or even no RX after transmission ?
The TX/RX relay is the culprit : Some dust (or whatever) avoid good contacts once back in receiving position.
I had this issue here and noticed that after a transmission (amplifier ON), receiver signals went down by MANY dB's (I remember an example of a station at S7 going down to S1 !!!!!!!)
Solution : No need to open the amplifier, just execute the following procedure to clean the relay contacts with your own HF signal !
1- Set your transmitter in FM mode, with an output power adjusted to 10w.
2- Set the AL811H with correct plate/load setting, in OPR position.
3- Check that the frequency you will transmit on is clear !
4- Key down the transceiver during 1 sec to check plate current < 400mA and grid current < 150mA (no bad tuning setting)
5- Release the key to go back in reception.
6- Keep keying-down the transceiver during 10 seconds max, and manually switch OPR/STD-BY switch of the AL811H while transmitting
(You should be able to switch from OPR to STD-BY, then OPR, then STD-BY etc about 10 times in 10 seconds)
7- Go back to normal mode (SSB or CW) and check if receiver signals are back to normal level.
Receiver signals are back to normal level ==> You solved the issue !
Receiver signals are NOT back to normal level ==> Repeat this procedure (I never had to repeat it !)
I had this issue here and noticed that after a transmission (amplifier ON), receiver signals went down by MANY dB's (I remember an example of a station at S7 going down to S1 !!!!!!!)
Solution : No need to open the amplifier, just execute the following procedure to clean the relay contacts with your own HF signal !
1- Set your transmitter in FM mode, with an output power adjusted to 10w.
2- Set the AL811H with correct plate/load setting, in OPR position.
3- Check that the frequency you will transmit on is clear !
4- Key down the transceiver during 1 sec to check plate current < 400mA and grid current < 150mA (no bad tuning setting)
5- Release the key to go back in reception.
6- Keep keying-down the transceiver during 10 seconds max, and manually switch OPR/STD-BY switch of the AL811H while transmitting
(You should be able to switch from OPR to STD-BY, then OPR, then STD-BY etc about 10 times in 10 seconds)
7- Go back to normal mode (SSB or CW) and check if receiver signals are back to normal level.
Receiver signals are back to normal level ==> You solved the issue !
Receiver signals are NOT back to normal level ==> Repeat this procedure (I never had to repeat it !)
Kudos to Bryan (WH7DX) who exposed problem and solution here : http://www.eham.net/ehamforum/smf/index.php/topic,93180.0.html