Zack,
Is that a CW/SSB only transceiver or does it support WFM? Since I'm
building a gunnplexer I'll be limited to that mode. That said, I'd love
some pointers on the antenna system. The gunn cavity has a small feedhorn
attached right now and I think that should give me about a 30° FOV and
maybe 17dB gain? I've also got a few satellite TV dishes which could bump
that to maybe 35dB at a couple degrees? Do my calculations seem right?

On Sun, Apr 25, 2021 at 10:41 AM Zack Widup via mvus-list <
mvus-list@lists.febo.com> wrote:

CW.

https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon

https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link

--
Trevor R.H. Clarke
Computer Science House
Rochester Institute of Technology
retrev@csh.rit.edu
http://www.csh.rit.edu/~retrev/

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I’ve played with test equipment up there but never have done any actual
radio however.
Many years ago played with some 20 GHz gunnplexers and saw some impressive
stuff at 10 mile distances, so I don’t think 24 will be much more
difficult. Trick is to use FM so that phase noise and frequency accuracy
aren’t as important.
I don’t have anything that uses that high anymore, but willing to help
tinker if needed

From Tom Holmes, N8ZM

mvus-list@lists.febo.com> wrote:

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Sounds like nobody has an existing 24 gunnplexor so I'll have to source
another somewhere for a second radio. The one I have looks like it's been
used in a tsp before as it's still got components attached. I'll include a
photo. The marked component is a metal film R.

My plan was to try and use an IF in the 2m band so I can connect directly
to a cheap baofeng and make an L band HT or connect to my mobile in the
car.

While I'm at it I need to put together some basic test gear. For a signal
source I found a nice little RF schottky multiplier built on the end of an
SMA connector and wire stub that I should be about to feed with my hackrf
and get enough harmonics to do a course tuning.
I'm looking for a cheap as chips wideband RF detector. Doesn't need to be
particularly stable or calibrated but it should be quite directional. The
plan is to have a portable unit I can use to align on a dish in the field.
Would a simple schottky detector with a small coil pickup and a metal box
with a slot with well enough or should I investigate something else

Trevor R.H. Clarke, K8TRC

On Sun, Apr 25, 2021, 1:41 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:

impressive

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I’ve played with test equipment up there but never have done any actual
radio however.
Many years ago played with some 20 GHz gunnplexers and saw some impressive
stuff at 10 mile distances, so I don’t think 24 will be much more
difficult. Trick is to use FM so that phase noise and frequency accuracy
aren’t as important.
I don’t have anything that uses that high anymore, but willing to help
tinker if needed

From Tom Holmes, N8ZM

mvus-list@lists.febo.com> wrote:

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Trevor...

Your detector could be simply a 1/4 wave stub in a short waveguide feeding
a Schottky diode, fronted by a horn. I doubt you could build a coil that
wouldn't have serious parasitic losses at 24 GHz. The gain of the horn
would help significantly, and you should be able to see the output on a DMM
or microammeter.

Tom Holmes, N8ZM

-----Original Message-----
From: Trevor Clarke via mvus-list mvus-list@lists.febo.com
Sent: Sunday, April 25, 2021 7:20 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Trevor Clarke retrev@csh.rit.edu
Subject: [mvus-list] Re: 1.2cm wfm

Sounds like nobody has an existing 24 gunnplexor so I'll have to source
another somewhere for a second radio. The one I have looks like it's been
used in a tsp before as it's still got components attached. I'll include a
photo. The marked component is a metal film R.

My plan was to try and use an IF in the 2m band so I can connect directly
to a cheap baofeng and make an L band HT or connect to my mobile in the
car.

While I'm at it I need to put together some basic test gear. For a signal
source I found a nice little RF schottky multiplier built on the end of an
SMA connector and wire stub that I should be about to feed with my hackrf
and get enough harmonics to do a course tuning.
I'm looking for a cheap as chips wideband RF detector. Doesn't need to be
particularly stable or calibrated but it should be quite directional. The
plan is to have a portable unit I can use to align on a dish in the field.
Would a simple schottky detector with a small coil pickup and a metal box
with a slot with well enough or should I investigate something else

Trevor R.H. Clarke, K8TRC

On Sun, Apr 25, 2021, 1:41 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:

impressive

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Trevor...

Your detector could be simply a 1/4 wave stub in a short waveguide feeding
a Schottky diode, fronted by a horn. I doubt you could build a coil that
wouldn't have serious parasitic losses at 24 GHz. The gain of the horn
would help significantly, and you should be able to see the output on a DMM
or microammeter.

Tom Holmes, N8ZM

-----Original Message-----
From: Trevor Clarke via mvus-list mvus-list@lists.febo.com
Sent: Sunday, April 25, 2021 7:20 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Trevor Clarke retrev@csh.rit.edu
Subject: [mvus-list] Re: 1.2cm wfm

Sounds like nobody has an existing 24 gunnplexor so I'll have to source
another somewhere for a second radio. The one I have looks like it's been
used in a tsp before as it's still got components attached. I'll include a
photo. The marked component is a metal film R.

My plan was to try and use an IF in the 2m band so I can connect directly
to a cheap baofeng and make an L band HT or connect to my mobile in the
car.

While I'm at it I need to put together some basic test gear. For a signal
source I found a nice little RF schottky multiplier built on the end of an
SMA connector and wire stub that I should be about to feed with my hackrf
and get enough harmonics to do a course tuning.
I'm looking for a cheap as chips wideband RF detector. Doesn't need to be
particularly stable or calibrated but it should be quite directional. The
plan is to have a portable unit I can use to align on a dish in the field.
Would a simple schottky detector with a small coil pickup and a metal box
with a slot with well enough or should I investigate something else

Trevor R.H. Clarke, K8TRC

On Sun, Apr 25, 2021, 1:41 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:

impressive

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Trevor,

I do believe you have a full-blown Gunnplexer there, not just the Gunn
oscillator.

Back in the late 1970's I bought an early pair of 10 GHz Gunnplexers from
MaCom,
almost immediately after they were introduced into that amateur market.
Did lots of
fun things with them running between the top of a 25-story apt bldg in
downtown
Ann Arbor and Peach Mountain, roughly 12 miles to the NW.  We tried both 2m
IF
and FM BC band IF- the latter was easier to work with because there was so
much
room in which to "flop around".  But the narrower band with the usual 2m
transceivers
did yield noticeably better S/N.

Later on we found an alternate site on the far west side of Ann Arbor,
namely the home
of Corwin (WB8UPM), and successfully established 2-way comm between there
and
the same location on Peach Mountain.

Pretty soon this operation between two fixed points got pretty boring, but
we
realized that Dayton was coming soon.  Eureka!  We'd try mobile operation
between
two cars as we drove to the hamvention.  The lead car would have its
antenna
pointed backwards, and the following car would point its antenna forward.

We had realized from the outset that some form of AFC would be necessary.
My own
FM BC receiver was built from Heath parts that were meant to be used in
their (then)
top of the line tuner.  I had simply bought the stuff from Heath's parts
department
while visiting my parents in St. Joseph, who lived within easy bicycling
range of the
big Heath Company "factory".  I'd been a pretty regular customer there
since early high-
school days and was known well (they ran for hiding when they saw me
coming).

I added AFC to my "tuner", and we began a series of rehearsals on I-94.
About the
first thing we discovered was that there were occasional signal
interruptions due to
big trucks or getting too far apart on curves, etc. During such
interruptions the AFC would
break lock and could not find its way home without considerable manual
intervention.
So I added a "quieting detector" to the FM tuner and arranged for it to
place the AFC on
"hold value" during signal interruptions.  This worked very well, although
over time it
could run into trouble maintaining lock if the temperature changed enough
to run the AFC
outside its control range.  So I added a 10-turn pot so that an operator
could watch the
AFC loop's error voltage and keep it tweaked reasonably close to center.
Said "operator"
would sit in the right front passenger seat, with the tuner and voltmeter
in his lap, and
would keep the whole thing working.

Further trials revealed that wind noise in the horns FM'd the Gunn
oscillators enough to
be quite annoying as it often excited an "organ-pipe resonance" in the WG
section between
each Gunnplexer and its horn.  That was fixed with some tight-fitting plugs
of foam
polystyrene inserted into the WGs just inside the horns.

The result was a really fun drive to Dayton that year, with full duplex
audio at pretty.
decent sound quality.  We found that we could interchange the positions of
the two
cars and continue communications. albeit at much shorter range (only a
couple hundred
feet IIRC).  That this worked at all presumably depended on double
backscattering from
trees, cars, etc ahead of the lead car and behind the following car.  I
have no clear
recollection of what the useful range was between properly disposed lead
and following
cars, but I think it was something over a mile, depending on the
intervening traffic density.

The other thing we noticed was that from time to time a car would be
passing the trailing
car, and suddenly slow down.  We surmise that these cars were using police
radar
detectors which did not have sufficient selectivity to reject strong
signals at 10.25 GHz.

It's too bad that this was before the advent of consumer video camcorders,
else we could
have put together an impromptu talk for the hamvention.  For some reason we
did not
think of doing any audio recording.

Dana

On Sun, Apr 25, 2021 at 6:20 PM Trevor Clarke via mvus-list <
mvus-list@lists.febo.com> wrote:

a

an

field.

accuracy

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Trevor,

I do believe you have a full-blown Gunnplexer there, not just the Gunn
oscillator.

Back in the late 1970's I bought an early pair of 10 GHz Gunnplexers from
MaCom,
almost immediately after they were introduced into that amateur market.
Did lots of
fun things with them running between the top of a 25-story apt bldg in
downtown
Ann Arbor and Peach Mountain, roughly 12 miles to the NW.  We tried both 2m
IF
and FM BC band IF- the latter was easier to work with because there was so
much
room in which to "flop around".  But the narrower band with the usual 2m
transceivers
did yield noticeably better S/N.

Later on we found an alternate site on the far west side of Ann Arbor,
namely the home
of Corwin (WB8UPM), and successfully established 2-way comm between there
and
the same location on Peach Mountain.

Pretty soon this operation between two fixed points got pretty boring, but
we
realized that Dayton was coming soon.  Eureka!  We'd try mobile operation
between
two cars as we drove to the hamvention.  The lead car would have its
antenna
pointed backwards, and the following car would point its antenna forward.

We had realized from the outset that some form of AFC would be necessary.
My own
FM BC receiver was built from Heath parts that were meant to be used in
their (then)
top of the line tuner.  I had simply bought the stuff from Heath's parts
department
while visiting my parents in St. Joseph, who lived within easy bicycling
range of the
big Heath Company "factory".  I'd been a pretty regular customer there
since early high-
school days and was known well (they ran for hiding when they saw me
coming).

I added AFC to my "tuner", and we began a series of rehearsals on I-94.
About the
first thing we discovered was that there were occasional signal
interruptions due to
big trucks or getting too far apart on curves, etc. During such
interruptions the AFC would
break lock and could not find its way home without considerable manual
intervention.
So I added a "quieting detector" to the FM tuner and arranged for it to
place the AFC on
"hold value" during signal interruptions.  This worked very well, although
over time it
could run into trouble maintaining lock if the temperature changed enough
to run the AFC
outside its control range.  So I added a 10-turn pot so that an operator
could watch the
AFC loop's error voltage and keep it tweaked reasonably close to center.
Said "operator"
would sit in the right front passenger seat, with the tuner and voltmeter
in his lap, and
would keep the whole thing working.

Further trials revealed that wind noise in the horns FM'd the Gunn
oscillators enough to
be quite annoying as it often excited an "organ-pipe resonance" in the WG
section between
each Gunnplexer and its horn.  That was fixed with some tight-fitting plugs
of foam
polystyrene inserted into the WGs just inside the horns.

The result was a really fun drive to Dayton that year, with full duplex
audio at pretty.
decent sound quality.  We found that we could interchange the positions of
the two
cars and continue communications. albeit at much shorter range (only a
couple hundred
feet IIRC).  That this worked at all presumably depended on double
backscattering from
trees, cars, etc ahead of the lead car and behind the following car.  I
have no clear
recollection of what the useful range was between properly disposed lead
and following
cars, but I think it was something over a mile, depending on the
intervening traffic density.

The other thing we noticed was that from time to time a car would be
passing the trailing
car, and suddenly slow down.  We surmise that these cars were using police
radar
detectors which did not have sufficient selectivity to reject strong
signals at 10.25 GHz.

It's too bad that this was before the advent of consumer video camcorders,
else we could
have put together an impromptu talk for the hamvention.  For some reason we
did not
think of doing any audio recording.

Dana

On Sun, Apr 25, 2021 at 6:20 PM Trevor Clarke via mvus-list <
mvus-list@lists.febo.com> wrote:

a

an

field.

accuracy

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