R2000 SSB "improvement"
 

A friend is making some PCB boards for my
AD607 synch detector project so I tried
something else.

Today was a REAL slow day at work. Someone
had to be thre "just in case", and as new
man I was bitten. So I took my original R2000
in to try an idea I hade for a while.

The product detector isn't the best design.
It uses a transformer to couple the IF to
the mixer bridge and a set of resistors to
couple the BFO. El stinkero.

I cut the traces and put a minicircuit 1:1,
secondary CT, between T18, removed the BFO
feed resistors and fed the BFO to the center
tap. I replaced the 1N60, (which where far
from matched!) with some old HP hot carrier
diodes (HP2800). The differnce between this
uit and a stock unit was night and day.

Very tedius work. But very worthwhile.

I have both radios complete, I ended up
staying an extra hour to complete this and
a rather plain "improved AM detector".

Before I reported that when I biased the AM
detector diode I experienced some very odd
happenings. I don't know what I did wrong,
but when I re did the experiment, it offered
a slight improvement. The AGC has it's own
detector. Just for grins I tried a hot carrier
and low voltage Shotky (zero bias) diodes.
They both worked but really wasn't enough to
bother with . The diode needs a negative bias
voltage and that is a big hassle.

Even though I have NO plans of ever taking
either R2000 out in the field again, I decided
to go on and add both these mods because they
are very worth the "minor" efforts. And for
this weekend I don't have my fancy synch detector.

Terry

Once you get all the upgrade mods to my old R-2000 done, I've decided I
want it back! :-p

Frank

fcath wrote:

Once you get all the upgrade mods to my old R-2000 done, I've decided I
want it back! :-p

Frank
-----------------
Er, dream on!

At best you aren't getting the Inrad fitler back. That fitler is MAGIC!

Thanks for the positive response to my question on "capacitor effect
on sound". That started this whole craze. That and the +95F +70RH
have given me plenty of incentive to stay in where it is cool.

While the simple op amp active detector is clearly not a synch
detector,it is so simple to build and it is so much better then the
stock single diode detector that every one who has a mid quality
receiver ought to at least think about it.

I have disassembled my bread board AD607 synch detector so
I was forced to lsiten to RCI/CBC's Vinyl Cafe' today sans sycnh,
but the active detector made it more then bare able. As I edited it
down for archive I noticed that when the studio switched from the
news to program the was a big jump in 60/120Hz noise. Their little
problem was hidden until I got better equipment. It might be that I
will
have to have a synch detector for weak/noise and use the active
detector for "high" quality SW.

Terry