[TenTec] Corsair II Mixer Balance Adjustment

[Steve Hunt]

I hear the 21,320 kHz "birdie" on both of my CorsairIIs at pretty high 
level.

The birdie tunes at 3 times the VFO rate; I believe it is the 9MHz 
product caused by:
3 x VFO - HFO = 3 x 5,330 - 6,990 = 9,000 MHz

The amplitude changes depending on whether I'm using my DDS VFO or my 
PTO - I guess they have different levels of third harmonic content.

You could try injecting a 9MHz signal directly on the LO input - 
connector 71 - and nulling that.

Hope that helps,
Steve G3TXQ





On 26/12/2012 18:35, K4MT wrote:
> I am finishing the work on my Corsair II and I decided to do the mixer balance adjustment.
> The manual says to null the tone at 21,320 but I have no tone there. I adjusted the alignment points for mixer balance thinking it might be already nulled but the null seemed to good to be true. Adjusting the null capacitor and pot produce no tone at all. I hear a tone at 21315 (yes, my dial is calibrated properly). I can null that tone but it kills the receive in that entire portion of 15 meters from around 21250 to 21400.  Surely that is not the correct one.
> Is there another way to do mixer balance adjustment or do I have a problem on that board? The radio seems to perform properly otherwise.
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