BATC Forum

The article in CQ-TV 260 by I2GLI rang a bell with me. He states that the 5.6GHz Chinese modules that we are all using do not include video pre/de-emphasis. Going back to the early days of FM TV on 23cm, Wood & Douglas were the major supplier of kit for the band. Very fine kit it was too, mine is still working after 33 years! Their early versions did not include video pre/de-emphasis and they then added the small module illustrated below. This was a dual purpose board, providing video pre or de-emphasis and included an amplifier and gain control to compensate for the network loss. This made a HUGE difference to our early transmissions across Bristol, raising a very noisy P2 signal to a usable P4. It might do the same for marginal 5.6GHz signals now that we are chasing record distances. I am assuming that W&D won't mind their long obsolete but not forgotten circuit being reproduced here!
73 Shaun G8VPG.

Thanks Shaun

As the circuit diagram for Achille's similar solution was a little difficult to read in the .pdf edition of CQ-TV, I have posted a clearer copy here https://wiki.batc.org.uk/File:BandaBase.jpg

Dave, G8GKQ

Interestingly that audio circuit and 6MHz osc etc looks very similar / familiar to my 24cm ATV design published in Elektor during the early 90's !

Uses the same 7611 op amp and component values as well - good to see it's still proving useful after all these years.