SSTV Hardware

Receiver and Transmitter

A few pieces of equiptment are needed to receive and transmit SSTV. The first items, of course, are the receiver and the transmitter. Older equiptment with frequency drift will cause a problem. Most newer pieces of equiptment are satisfactorily stable and will work fine.

Many rigs have supplemental audio output and input connections besides the speaker and microphone jacks. Sometimes these are referred to as "phone patch connectors", "modem connectors", or "accessory sockets".

For receiving SSTV, what we want is a source of audio about 100 to 500 mv in strength. It is handy if this level is not affected by the volume control on the front of the receiver. Many of the recent Kenwood HF transceivers have a socket on the rear of the rig called "ACC2" that provides 300 mv of audio, and is not affected by the audio control. The new Yaesu 847 provides audio, but at about 30 mv, it is too low to be any good. The speaker output is often the only choice.

Transmitting SSTV requires 2 items, an audio input to the transmit section of the rig, and, usually, a connection to the Push to Talk (PTT) line. A well designed supplemental audio input section is very helpful. Some have had to unplug the microphone and plug in the SSTV source, some have resorted to mechanical switches, but the best solution is one in which the SSTV source does the switching automatically. The PTT line is most commonly used, but some have actually used the Voice Control (VOX) circuitry to switch to transmit when the SSTV audio from the SSTV generator is sensed.

The Kenwood ACC2 socket also provides an audio input separate from the microphone, and it has a special PTT input that when actived will disable any input from the microphone, and extremely handy feature.

My Yaesu 736R that I use for VHF and UHF SSTV has a special connector on the back for supplemental audio input and output, but the PTT line does not shut off the microphone audio, so everytime I transmit SSTV, I have to manually turn down the microphone gain.

SSTV Display and Generate

Originally SSTV was received or transmitted on a piece of hardware designed especially for SSTV. But over the years, as Personal Computers got more and more powerful, it became possible to load specialized software into a generic computer to allow it to become a piece of SSTV equiptment one day, and a have a completely different application the next day.

Yet there are still many people who like a dedicated unit that can be optimized strictly for SSTV. If SSTV is to be your only use for the equiptment, this may be the cheapest way to go, in fact.

But for most people, the low cost home computer that can be used for many uses besides SSTV makes the most sense, and by sharing the cost over several applications, the additional application of the computer to SSTV, represents a very small cost to get on SSTV.