"George R. Gonzalez" writes:


"Eric S." wrote in message
.. .
I've been eagerly following the long-ongoing discussion on building a
high-quality AM tube tuner which would excel at both sensitivity and
audio fidelity.

It got me to thinking that maybe a tube/digital non-superhet hybrid
makes sense, to combine the old with the new. However, before I
present my idea, let me state very clearly that my knowledge of radio
circuitry is very minimal, so the idea may be beyond silly, or it's
already being done in some incarnation. So, be gentle with me, LOL.

The idea is after the first-stage tuning which uses a tube-based
circuit for low-level amplification, to digitize the weak signal

snip

Tube/digital would be lots of fun, but use the best of both. SuperHet
down to base band and then use DSP to select AM/FM/CW, etc. with
programmable filters. Run the RF gains with lots of local feedback and
low gain to get low intermod. Use a DSP controlled analog preselector.
Use a digital LO and micro control of the tracking.

Lots of work, but you can most of the algorithms in "digital radio" books
and IEEE articles. The tube stuff is well known.

Have fun.

Steve.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA