Hi Steve - Yep that was exactly the basic idea from a 1980's Ham Radio mag article.  The idea was to use one of those cheap TV tuner modules and drive the VCO with a controllable ramp.  I did that, but added bells&whistles to suit my needs. (Which was to train field radio operators on the obvious consequences of simply pushing the Transmit button...)

It was a fun, useful project....
Tim
N6CC

On Thu, Sep 28, 2023 at 11:47 AM Steve KM4V <Highpwr@bellsouth.net> wrote:

Tim,

 

Sounds like the old “Poor Man’s Spectrum Analyzer” from back in the 80s or 90s.

 

Steve

KM4V

 

From: mrca-bounces@mailman.qth.net <mrca-bounces@mailman.qth.net> On Behalf Of Tim
Sent: Wednesday, September 27, 2023 4:33 PM
To: MMRCG@groups.io; RAFANTINI@salisbury.edu
Cc: mrca@mailman.qth.net; milsurplus@mailman.qth.net
Subject: Re: [MRCA] [MMRCG] AN/APA-38 Panadaptor

 

Hi Ray - Sounds like a fun project.  I don't have a display for my APR-1 either but I needed a portable ESM spectrum analysis receiver that covered 30-500 mc.  Doesn't seem to be something available in "military surplus" so I built my own in an ammo can.  Based on an old analog TV tuner module driven by a ramp generator for the tuning sweep.  Works great with an external scope.  

 

"No signal goes unnoticed..."

Tim

N6CC

 

On Wed, Sep 27, 2023 at 12:50 PM Ray Fantini <RAFANTINI@salisbury.edu> wrote:

Is doing something completely pointless sane? I was recently so impressed by some of the aircraft radio dioramas at Gilbert that I have decided that I would like to try to attempt one myself.  First let me start by saying that one of the tools I use at work almost all the time is a spectrum analyzer, everyone knows that much has been rolled out in the past years from companies like Rigol with a line of spectrum analyzers with internal tracking generators for under one thousand dollars or the little Nano VNA vector network analyzers so today anyone can have a spectrum analyzer or VNA that would have easily cost five or ten grand ten years ago, and brand name analyzers like the HP ESA family and not out of the range of most people, but I want to take a giant leap backwards and build up my EW/ECM warfare “primitive” analyzer by kitting out my APR-4Y with a AN/APA-38 panadaptor.  The old APR-1 and 4 all worked with a larger display, the APA-10 but never warmed to those old receivers being the 4Y had just one head for covering all four bands and had enough sensitivity to almost be called a receiver along with an added FM demodulator.  I have a APR-4Y with head and rack but lack the AN/APA-38 scope and think if I can come up with one that would be the good basis for a complete search receiver from the old days, a primitive spectrum analyzer.

So if anyone has one that can be talked out of please let me know.

Have already seen where a ARC-21 has shown up so there must still be more unicorns out there.

 

Ray F/KA3EKH

 

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