MA197B Pre-Selector and Protection Unit



Well what can one say about the MA197B..?

Imagine operating an RA17/RA117 full duplex with a 1kw transmitter on the same site,possibly with a common aerial.Yes even the bomb proof front end of these receivers would struggle a bit with this sort of setup.Enter the MA197B.

This unit, which is tuneable between 2-24 mhz will give between 85-100db attenuation of frequency with 5% difference to the wanted signal..!! It can also sink RF up to 40 volts emf to protect the receiver from damage.So if you use one of these with say an MA174 or MA1970 then forgetting to disconnect your RX aerial when you key up your 2kw linear should not be a problem.!!

On ranges 2-24 mhz the signals go through a two stage amplifier with a nominal gain of 6db.

Various Models.

MA197A HF Receiver Pre-Selection and Protection Unit 2-30 Mhz
MA197B-1 Protection and Pre-Selection Unit to RAF contract
MA197B-2 Protection and Pre-Selection Unit for use with RA133 and general commercial applications. Fitted with bollards for cabinet mounting
MA197B-3 As MA197B but to special requirements for dutch Navy
MA197C Drg DA605066/A As MA197C but with modified front panel and handles
MA197C Modified MA197B-1 for use with RA17/117 and RA217/1217

Updated 05/03/2002

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MA1970 receiving aerial multicoupler

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