[AMRadio] RE: Yet another receiver update!

[Brett Gazdzinski]

Hello all AM,ers,
I have been fooling around with it again.
In an effort to reduce some of the drift, I built an oscillator circuit out
of an ARRL handbook (1966?).
It uses a grounded cathode, and an un tapped coil with no
separate feedback coil, rf choke on the B+ feed to the plate.

Well, it works fine but still has the drift, even with npo
caps.
I suppose I would have to run the filament in the 6j5
all the time if I want no drift, but don't think I will do that,
as I power everything in the rack off at one switch, and
don't like the idea of running a filament all the time.

Part of the problem was solved by using a digital frequency display.

Almost all digital electronics has a kit for $50.00 that is really
swift. Its a handful of parts, but works very well.
Takes about 1/2 hour to build, and can directly read a frequency,
or offset it by any amount plus or minus.
On my receiver, I offset 455 kHz and it reads out the
receive frequency.
7.290.0 MHz, or 7.290.00 MHz (jumper selectable).
A short pickup wire close to the 6j5 picks up the LO frequency.
It seems very accurate.
I bought the backlit display option, and it runs fine off the 8
volts dc I have in the receiver.

With the digital readout, I checked the drift.