On Dec 25, 10:35*am, "COLIN LAMB" wrote:
It is possible that the powder used at 455 kHz is quite lossy at 3.395 MHz.
Usually, a quick and dirty way to tell is if the peak is sharp. *The broader
the peak, the lower the Q.

Will try to get my manual out to review it for clues. *I suspect your SB-610
sensitivity is below par.

73, *Colin *K7FM

Colin,

Regarding the possible low Q, the pre-amp has the same tank circuit as
the 6EW6 grid circuit: a 330 pF cap in parallel with a 6.7 uH coil.
The coil is comprised of about 25 turns. When I bench tested the pre-
amp, I recall computing a Q of 30 for the tank circuit. These seemed
reasonable at the time, although your explanation about the lossy core
material plausible.

Your help is much appreciated. Let me know what you think.

-Dave Drumheller, K3WQ