Thanks Gregg! We are still putting together a group of specs, from this NG
feedback. I have been using a DDS for awhile, but that itsn't as clean as I
would like it to be. Mini-Circuits doesn't have a good tracking VCO that
will cover the 10.7MHz tuning range, so I decided to design my own low
noise, tracking output VCO. My 2nd and 3rd harmonic specs are -25dBc and
-35dBc respectively. With a diode ring mixer, anything greater
than -20dBc puts you in the ball park.

Gregg wrote in message
news:0HW7b.108328$kW.105052@edtnps84...
Behold, Pete KE9OA signaled from keyed 4-1000A filament:

Hi Gregg,
That is exactly what I plan to use..............I have
been
using that topology for several years now, so I've got the Diplexer
design nailed down pretty well.

You sir, are a god! Do you know how many people that are so-called
"engineering professionals" that do not know how to diplex the output of a
diode DBM?

I'm sold, when can I buy it ;-)

I do know what you are talking about.............not everybody thinks about
reducing the noise from the image frequency. My diplexer has a selectivity
of right around 15kHz. I chose the X values to be about 43 Ohms, so the
tuning characteristic is fairly sharp.


I am not sure why more manufacturers don't use doubly-balanced mixers,
especially when you can purchase a Mini-Circuits ADE-3 mixer for around
3 dollars.

Because they can pay 15 cents for a 2SCxxxx.

It all comes down to money. Nothing is about quality, just mark-up and
useless features.

You seem to be doing something that hasn't been done since the late 1950's
- engineering a soul into the unit :-)

You have my highest respect.

Thanks again, Gregg. I contacted one of the high end audio dealers here in
Chicago yesterday, and they seemed pretty excited about the project. We are
definitely moving ahead...................we've already chosen the PLL
(145170), so we just need to verify long term availability. I will be
contacting Murata and Phillips today, about setting up some sort of
relationship. I used to deal with these folks quite a bit, from my Motorola
days.

Pete