SSTV TX Video Converter - WA9UHV

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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SSTV TX Video Converter - WA9UHV

Postby Harry Dalek » Wed Jan 17, 2024 11:22 pm

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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTV TX Video Converter - WA9UHV

Postby kd2bd » Thu Jan 18, 2024 6:53 am

The WA9UHV "converter" actually modifies the vertical sweep rate of an NTSC camera from 60 Hz to 15 Hz, and uses an analog sampling technique to produce a 90 degree rotated SSTV image from the modified FSTV camera.

Notice the use of the VCO section of an LM565 PLL to generate the SSTV audio signal. Unfortunately, it, like the LM566, is also now considered an obsolete component.

73 de John, KD2BD
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Re: SSTV TX Video Converter - WA9UHV

Postby Harry Dalek » Thu Jan 18, 2024 7:39 am

kd2bd wrote:The WA9UHV "converter" actually modifies the vertical sweep rate of an NTSC camera from 60 Hz to 15 Hz, and uses an analog sampling technique to produce a 90 degree rotated SSTV image from the modified FSTV camera.

Notice the use of the VCO section of an LM565 PLL to generate the SSTV audio signal. Unfortunately, it, like the LM566, is also now considered an obsolete component.

73 de John, KD2BD


Funny enough i do think i have one Lm565 in a round package ! and makes it a bit of a pain to mount when they used this idea for ic's .

Thanks for the circuit description had me confused why there was a ramp generator
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTV TX Video Converter - WA9UHV

Postby Steve Anderson » Thu Jan 18, 2024 12:24 pm

I haven't re-visited that Eevblog forum in 7 years after a rather negative posting in response to one of mine...

"I undestand your hate for PC-everything...." A rather negative take on what I actually said, to which I followed with...

"The PC route is a perfectly valid way of doing things, please don't get me wrong, it's just not the way I choose to do it."

It went on for a while longer, then I simply didn't bother anymore...we have a number of NBTV PC applications as well as SSTV versions here via links or the actual software for download. I have no objection whatsoever.

I could use the car to go to the local shops, but instead I choose to use a bicycle. It's not an environmental thing, otherwise I wouldn't use and fly an aircraft that uses 12 US Gallons per hour in a 65% power cruise. It's my choice, thankfully I live in a country that allows that freedom.

It seems that whoever wrote that comment want's that everyone who enjoys SSTV must use a PC to do so.

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Re: SSTV TX Video Converter - WA9UHV

Postby Harry Dalek » Thu Jan 18, 2024 2:28 pm

Steve Anderson wrote:I haven't re-visited that Eevblog forum in 7 years after a rather negative posting in response to one of mine...

"I undestand your hate for PC-everything...." A rather negative take on what I actually said, to which I followed with...

"The PC route is a perfectly valid way of doing things, please don't get me wrong, it's just not the way I choose to do it."

It went on for a while longer, then I simply didn't bother anymore...we have a number of NBTV PC applications as well as SSTV versions here via links or the actual software for download. I have no objection whatsoever.

I could use the car to go to the local shops, but instead I choose to use a bicycle. It's not an environmental thing, otherwise I wouldn't use and fly an aircraft that uses 12 US Gallons per hour in a 65% power cruise. It's my choice, thankfully I live in a country that allows that freedom.

It seems that whoever wrote that comment want's that everyone who enjoys SSTV must use a PC to do so.

Steve A.


Yes its not one or the other its is what it is many ways to do the same thing and if you are to lazy to build any thing why bother replying !
As with NBTV or SSTV Television or FAX it can be mechanical electronic and which is better up to the individuals interest .
I can see why you left that forum least here most those that stick around do have the same interests !
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTV TX Video Converter - WA9UHV

Postby Steve Anderson » Thu Jan 18, 2024 4:05 pm

Thanks Harry. I did mention a long while ago that a mechanical SSTV camera was on my 'to do' list, and it still is. It would still use a moderate amount of electronics, but the actual scanning would be mechanical. I'll look through my 'to do' list (an Excel spreadsheet) and perhaps give it a kick up the priority list.

There is not much difference between SSTV and FAX, it should be possible to combine the two in one unit. I'll need to find the definitive FAX standards for transmission and reception first...any suggestions?

Steve A.
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Re: SSTV TX Video Converter - WA9UHV

Postby Klaas Robers » Fri Jan 19, 2024 3:24 am

For the 'modern' SSTV-modes with colour and more lines, I sugested to use a JPG format and send that over in a digital way. It will use less time. But nobody became enthousiastic for that idea....
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Re: SSTV TX Video Converter - WA9UHV

Postby Harry Dalek » Fri Jan 19, 2024 8:30 pm

Klaas Robers wrote:For the 'modern' SSTV-modes with colour and more lines, I sugested to use a JPG format and send that over in a digital way. It will use less time. But nobody became enthousiastic for that idea....


There is a Digital SSTV program which does not seem any longer than the old colour SSTV modes to transmit but for me i like the good old days and analogue .

Here we should keep the old technology alive people these days are so spoilt with HD every thing sitting in their hands but with no knowledge or interest in the past .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTV TX Video Converter - WA9UHV

Postby Harry Dalek » Fri Jan 19, 2024 8:40 pm

Steve Anderson wrote:Thanks Harry. I did mention a long while ago that a mechanical SSTV camera was on my 'to do' list, and it still is. It would still use a moderate amount of electronics, but the actual scanning would be mechanical. I'll look through my 'to do' list (an Excel spreadsheet) and perhaps give it a kick up the priority list.

There is not much difference between SSTV and FAX, it should be possible to combine the two in one unit. I'll need to find the definitive FAX standards for transmission and reception first...any suggestions?

Steve A.


Good that's still on your mind not to many 120 line SSTV cameras out there and in not Zero mechanical versions !
The old Noaa weather satellites use Fax none stop fax really ..Have not really looked into fax for a while you would want the fastest as it can be very slow .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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