Sorry if this is a 2nd post, the network ate my first attemt.
-----------------
Several months ago I asked a question about why Kiwa suggested
replacing the Si switch diodes in teh IF with Shottky diodes
and suggested PIN diodes for the front end.

I am causing trouble in another group and posed a similar question.
It wasn't that I thought Pete, who has been very helpfull!, was
wrong, it was more to bring the topic up for a general review.
I am seding this to Pete via Email.
-------------------------------------------
gandalfg8@a... wrote:
In a message dated 19/07/2005 18:00:06 GMT Daylight Time,
r2000swl writes:
PINS do a good job with the ocatve RF bandpass filters on
my R2000s, I guess they will work well for this detector.
-----------
Hi
Included below is an extract from the manual for the Cubic 3030, a
high quality mil spec HF receiver.
It's part of the description relating to the switched preselector at
the front end, and I'm not sure exactly what this implies for PIN diode
switching of filters at 455 KHz, but thought it worth a mention......

"The half-octave bandpass filters serve to exclude out-of-band
energy that could result in receiver spurious responses and also
serve to reduce the local oscillator signal that may be conducted
from the mixer in the 1st IF module.
The filters operating above 1.6 MHz are PIN diode switched whilst the
filters for the lower frequencies are relay switched.
Relay switching is used for the lower frequencies as PIN diodes have
excessive distortion at low frequencies."

regards

Nigel
----------
I wrote:
------
Thanks for the information.

This may well be why Kiwa specifies Shottky diodes.

This weekend I may get a chance to take my "diode switch
test jig" into work and test it with a Tektronix Spectrum
Analyzer.

I will look for harmonic distortion and intermodulation
distortion. I have a Minicircuits power divider that
with a couple of ~10dB pads can be used to join 444KHz
and 446KHz RF signals. It ought to be "easy" to get some
valid numbers that really mean something.

I am going to send your Email and my response to Pete
and post it to the rec.radio.shortwave group.

I am raising questions here before I build. IT is a lot
easier to fix during the drawing stage instead of
after it is built stage.

Terry
-----------------
Anyone here with any thoughts?

What type diodes do Drake and Icom
use in their high end receivers?

Terry