BATC Forum

These will be getting thin on the ground now, But they do come up at rallies every so often. L.G.T. Paris now part of Thompson, made series of Rf modules that where used in (manly) the original I.T.V. UHF transporter stations. They all model number like 431/xxx. The supply requirement is 28Volts, modules ranging from 7db (1watt)- 16db (0.5watt) to higher power 7 db (5watt) versions; plus a mixer module. All can be identified by big heat sinks on one side. The circuit configuration is push pull on all of them These work very well on digital modes. Beware there where 3 variants, Band IV ( some are still working down at 146Mhz), V ( not much good as we do not have the 33cm band) and broadband. I have the details on these if anybody needs it. Worth looking out for at rallies and the like.

Hello
Our club has some UHF TV kit. I'll post pictures of some of the items. These will probably go for sale at rallies in 2023. First up today is a Screen Services SCR200IJ unit. To my untutored eye it looks like a transverter taking in TV on one channel and retransmitting it on another perhaps to a local site at a lower alitutude. Comments or recollections welcome
73
David M0YDH

Yes Dave,
It is a UHF transposer. Many TV relay stations were re-engineered with these Italian sets in preparation for the digital switchover. They were capable of operation on either system with minimal work on the changeover day. Probably a 2W set (That is 2W peak sync. plus sound at -13dB plus Nicam at -20dB) At Switchover a 2W station normally became 0.4 W digital. The input filters will be 8MHz bandwidth and I would expect to see an output filter as well but that could be in a 4 channel combiner as a separate unit.

Ken

Thank you Ken for the informative reply. This hand built marvel of engineering will probably sell as a 3U chassis with a 10MHz TCXO and a few patch leads.

I'm going to post pictures of a Teletext inserter next. This one is labelled Channel 4 Main. It powered on and did self-test from which it concluded that the PSU was OK and it had no inputs.
I wonder if any TV club member will want one to play with? Otherwise it's an aluminium 1U box with a 160mA output main PSU

73
David M0YDH

Next item is one of several Q amplifiers by Continental Microwave. I wonder if anyone has recollections of these? A pair of TPV695A Transistors feed into a IH0264/3 combiner or circulator [because there's a load resistor attached]. https://www.alldatasheet.com/datasheet ... V695A.html . They appear to 50V devices. Were these used with a transposer? There are lots of 440-880MHz markings on parts. I wonder if they can be repurposed on 437MHz?

73
David M0YDH

I am not familiar with these, but I would say:
1) The data sheet for the transistors says 25 v operation.
2)The splitter and combiner are 3dB Hybrids. Almost certainly 3dB couplers, as these have a much wider bandwidth than any other type.
3) Likely for 2W in and 10W out (Analog TV) after a 2W transposer, as these were the usual powers for small relays. Class A, 90W DC input.
4) Those transistors have been operating at close to their maximum rating, 24/7, for possibly 20 years!

73, Ken

Hi David
I am sorry to say I am unable to help with the CML device you have shown in your post.
It is probably something made before my time at CML
I did not join CML until 1971 and worked there until the factory closed in 2003
That type of construction should make it possible to be tweaked for 70cms.
Good luck
73 Arthur
G4CPE