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Sparky67 · 28th Oct 2020, 9:50 pm

Hi all,

I bought a Racal VRM4156 HF transceiver recently which has non-working AGC. The AGC IC, a CR711476, is u/s and the output has been set to provide mid-range AGC volts with a skeleton pot. The IC is a 10-pin thick film device.

I would very much like to return this to a working state, so I have two questions...

Does anyone know of a source of this IC, or an equivalent please?

Does anyone know of a suitable circuit which could replace this IC? The DC output range on a working set is 0.4V with no antenna connected, 4.3V with an antenna connected to 4.75V with a strong signal.

Any thoughts would be very gratefully received.

Diagrams attached.

Many thanks.

Martin
G4NCE

28th Oct 2020, 9:50 pm	#1
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Racal VRM4156 AGC Fault Hi all, I bought a Racal VRM4156 HF transceiver recently which has non-working AGC. The AGC IC, a CR711476, is u/s and the output has been set to provide mid-range AGC volts with a skeleton pot. The IC is a 10-pin thick film device. I would very much like to return this to a working state, so I have two questions... Does anyone know of a source of this IC, or an equivalent please? Does anyone know of a suitable circuit which could replace this IC? The DC output range on a working set is 0.4V with no antenna connected, 4.3V with an antenna connected to 4.75V with a strong signal. Any thoughts would be very gratefully received. Diagrams attached. Many thanks. Martin G4NCE Attached Thumbnails