Rob wrote in
:

Nikon D3000 wrote:

"Michael Black" wrote in message
ample.net...
On Thu, 23 Sep 2010, Nikon D3000 wrote:

Some folks just can't leave well alone!

Another way of looking at it is that a commercial receiver makes
a good start at a semi-homebrew project.

I always start from scratch. I build my own PCB's, wind my own coils,
metal enclosures and chassis. If I was capable of making all my own
components, including tubes, I would sure would give it a go - real
homebrew!

http://paillard.claude.free.fr/


Well! Do some folks REALLY thing that an FRG-7 is good enough as it
stands!!!
First and most important problem, lousy selectivity, about 6khz BW with
very poor shape factor.
Secondly very poor AGC performance, this can easily be improved with an
HCD as AGC detector and better biasing of the AGC stage and detector.
Thirdly not very good RF noise and linearity performance. Easily improved
with a better FET, better biasing and introducing an RF gain control in
the G2 circuit, while keeping AGC action on the stage.
Finally too fast a tuning rate for easy SSB tuning. I am investigating
mods to the tuning mechanism to give me another 5 times slower rate.
BTW I have made 8 complete homebrew ham stations in my career and have
WAC and about 160 countries with them.
This INCLUDES receivers.
Admittedly an Xtal controlled CIO is a luxury, but I had found a not
inconsiderable drift in the original SEO oscillator that I had rather do
without. As has been said it makes the basis of quite a good receiver,
once a few bugs are removed.
After the RF stage my next target will be the first balanced mixer. It
looks to me as if the stage could be set up to reduce intermodulation
quite a bit.
However at my age starting right from scratch is not so easy so turning
a leather purse into a silk one is easier and quicker. My TS-820 has had
the same treatment and now runs ALL HF bands.
&#'s Cliff Wright