Some of Master Builder K7YZZ's Homebuilt SSTV Test Gear

(Turn Louie loose in a Radio Shack Store, and give him a can of spray paint & decals, and watch out!)

 

 

AUDIO FREQUENCY METER FOR SSTV This is the first piece of test equipment I made for use when building my SSTV stuff. Gervie had this kind of gear and gave me the diagram so I could make one for myself. You connected it to the audio output of your SSTV signal and the meter would tell you if your sync, black, grey and white frequencies were correct. Very simple and it worked like a charm..    

 

    

After working on several of the early SSTV projects I decided to see if I could build a test gadget that would put out SSTV signals that could be used in checking out monitors etc. This effort resulted in a unit that acts like the fast scan TV test generator that I have from Heathkit. The output from this SSTV Signal Generator will produce vertical bars, horizontal bars, white screen, black screen, adjustable grey scale etc. I received requests from several hams to send them an audio test tape cassette that contained recorded SSTV signals from this generator and pictures recorded from the flying spot scanner. They used that tape recording to check out their SSTV monitor, and to play it over the air as a test signal. The test unit only works in the 8 second SSTV mode.

 

When I began constructing my first SSTV gear I found that trying to look at the very slow wave patterns on my EICO scope that had a P-4 screen was very difficult. So built myself a new scope that used a square display tube with a P-7 screen. Now I could view those creepy wave forms with no problem..Since the circuit was taken from my old EICO scope I had no problem learning how to set it up and look at what I wanted. I still have that scope and recently when my Heathkit solid state scope died I hauled the old home made unit out of storage and it still worked perfect. Can't beat that old tube type equipment.

 

This little gadget uses solid state filters to pick out the sync, black, grey, and white frequencies from a SSTV signal. The output from each fixed frequency audio filter is used to drive a LED to indicate the presence of that frequency. The idea for this unit came from early efforts to make a SSTV monitor tuning indictor that would show you when you had the receiver tuned to the sync signal. I just added more tuned filters to the design and boxed them up into the unit shown in the photo. This gadget was also written up and published years ago in 73 Magazine.

 

Not long after we all got interested in SSTV a chap with the call W0LMD published an article that described a home built digital counter. I figured that is what I needed to really determine just what my transmitted video signals frequency really were. So I built up the counter. It has bulbs that light up when an audio signal is fed to the unit. You then add up the numbers by each illuminated bulb and that will be the actual audio frequency of the SSTV 's sync, or black, or white, signal. This little unit was easy to build and very much less expensive than a commercial digital counter at that time.

 

As the time went by there began to appear all kinds of circuits from W0LMD covering different types of gear applicable to SSTV building projects. One of these was a neat little standard signal general that provided high accuracy switch selectible frequencies in the SSTV and RTTY audio frequency spectrum. That got the attention of this builder of SSTV and RTTY gear so I built one for myself. It met all of my expectations and after all these years it still works and is right on frequency.