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How to check LPF / relay failure that may be lowering power output


sumit basu
 

I get about 12 watts at 80m which progressively goes down to about 6 / 7 watts at 30m when measuring with a watt meter in CW mode. From 20m on-wards the watt-meter momentarily deflects when the key is pressed with ptt clicking in and instantly the needle goes down no transmit power after that. If i try test point 7 on the board with a wire to the watt-meter on 20m i get a deflection indicating about 5 watts progressively going down to 1 watt or less in 10m. Testing from test point 8 for these bands shows no deflection other than when the ptt clicks like earlier. I doubt something with the LPF's and /or the relays, how can i check this. Replacing relays is difficult - can anyone guide me a troubleshoot?
I was calling CQ on CW on 20m with 24 volts to the PA, the meter was showing power output around 25 watts and then came smoke. The transmit / receive was not working after that and after replacing both the 510's, Q15 and K1 things got OK except transmitting on 20m till 10m.
I am using v5 board with the cec 1.2

Sumit Basu
VU2DTF


 

Sumit,

One of your filter relays or associated components in the filter may have failed.

Higher power means higher voltage across capacitors etc.

Raj

At 15/06/2020, you wrote:
I get about 12 watts at 80m which progressively goes down to about 6 / 7 watts at 30m when measuring with a watt meter in CW mode. From 20m on-wards the watt-meter momentarily deflects when the key is pressed with ptt clicking in and instantly the needle goes down no transmit power after that. If i try test point 7 on the board with a wire to the watt-meter on 20m i get a deflection indicating about 5 watts progressively going down to 1 watt or less in 10m. Testing from test point 8 for these bands shows no deflection other than when the ptt clicks like earlier. I doubt something with the LPF's and /or the relays, how can i check this. Replacing relays is difficult - can anyone guide me a troubleshoot?
I was calling CQ on CW on 20m with 24 volts to the PA, the meter was showing power output around 25 watts and then came smoke. The transmit / receive was not working after that and after replacing both the 510's, Q15 and K1 things got OK except transmitting on 20m till 10m.
I am using v5 board with the cec 1.2

Sumit Basu
VU2DTF