Good Day all!
I have recently got one of these sets and am rapidly upgrading the original
design.
So far it has a Kokusai Mech filter, manual and AGC Rf gain control on the
RF stage. It has also had improvements to its AGC system and I am about to
update the RF stage FET.
One problem has arisen and someone might be able to help me here.
The Kokusai filter is NOT actually on 455 kHz, it's actual centre frequency
is 454.2 kHz (measured against a calibrated frequency counter), Since the
self excited BFO is NOT drift free I want to replace it with USB/LSB Xtals.
Can you still get the old time FT241 types, or does anyone know a source of
odd frequencies in the 455/465 kHz IF range?
I calculate that the the old FT241 channels I would need would be 328 and
326. That would give me BFO frequencies of 455.55 (should be 455.7) and
452.7 kHz that fits in with the odd filter.
That way one of the main sources of drift should be almost gone.
I have found that the FRG-7 has its problems, but, as someone who has
designed and built many communication receivers over the years IMO it is
the basis for quite a useful general coverage receiver and a VERY useful
bit of test gear with noise bridges etc.
Any suggestions gratefully received.
73's Cliff Wright ZL1BDA ex G3NIA New Zealand.