[TenTec] TEN TEC Corsair II weak reception

Reeve Family reevefamily at cogeco.ca
Wed Jun 8 07:44:58 EDT 2016

Regarding Marco's IS0KYB posting about the Corsair II weak receive
condition.I had the exact same issue with my Corsair II that I have owned
since new. Like Marco I suspected the problem to be diodes related to T/R
switching, however the problem turned out to be in the High Pass Filter
circuit on the LPF-TR board (80969). Symptoms were identical to what Marco
is indicating, and I found that receive strength was normal if I connected
the antenna to the 'RX ANT' connector on the rear panel, which effectively
bypasses the SWR  and LPF-TR boards (and the High Pass Filter).


My original TEN TEC manual has notation showing "OPTIONAL HIGH PASS FILTER
NOT INSTALLED" . However once I got the LPF-TR board removed I discovered
that the "Optional" High Pass filter was in fact installed contrary to the
notation on the schematic. Trouble shooting eventually led me to
disconnecting and bypassing the High Pass Filter and receive performance
issue was resolved. I did this by opening the circuit at the input to the
High Pass Filter and bypassing it with a capacitor between Q2 collector and
the RX connector to avoid interfering with operation of Q2. It has worked
fine ever since and no noticeable issue without the "Optional" High Pass


The biggest challenge in all of this was getting the LPF-TR board out of the
chassis which required careful removal of the Band Switch shaft while
ensuring that all of the Band Switch wafer sections were in the correct
position when reinserting the switch shaft. 


Like Marco, I would also like to know of a suitable PIN diode replacement
for the TR switching on the board as TEN TEC did not include details of
those components on the LPF-TR board schematic. Fortunately mine is still
fine after 28 years but I suspect one day I will need to replace those


Hope this helps.






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