[Collins] WTB Balanced modulator FA4200E

[Dr. Gerald N. Johnson]

On Mon, 2008-11-24 at 09:49 -0800, Dutch Maurer WB7DYW wrote:
> Gang, 
> I am looking for a Balanced modulator FA4200E for the KWM-2A, I know SSN has them at $70, any source for them elsewhere?? Or maybe someone has a spare for sale??
> 
> 
> 
> 73's Dutch WB7DYW
> 
> 
It appears fm-tx in Sweden has one and has posted it for sale on most
world wide epay servers except US and Canada.

I'd think about using something like the Avago Technologies HSMS-2827
Schottky ring quads as a replacement or maybe a minicircuits SBL-1-1 or
SBL-3 double balanced mixer though its impedance is surely lower than
the original circuit. I'm sure a quad of Avago 2835 Schottky diodes
would perform well, and if from the same batch probably wouldn't need
matching.

Remember they started out with a couple hard to keep matched germanium
diodes and then going to "factory matched switching" diodes was a great
improvement. A modern Schottky diode ring quad should be even better
about carrier suppression and long term balance.

Perhaps a reference: http://www.avagotech.com/docs/AV02-1100EN
supposedly .pdf, for sure an applications note.

Maybe search Mouser for "quad diode". Turned up Avago, TI, parts.

http://www.avagotech.com/search/results.jsp?src=&siteCriteria=HSMS2829

http://www.avagotech.com/search/results.jsp?src=&siteCriteria=HSMS2827

http://www.ti.com/lit/gpn/UC3611

http://www.diodes.com/datasheets/ds30195.pdf

Those are in stock.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer