OBSERVATIONS FROM SCOTLAND                            24 August 2008                   GM1SXX

The RA1772 & MA1720 meet.     Heavy Metal radio.

Well, I discovered something about the MA1720 I didn't know before. The protection system locks it out of transmit until it has been on for a few minutes.  (Hint.... it has a crystal oven).

The MA1720 TX Driver perched on top of the RA1772 receiver

You can't see it in the photos, but the right side of the front panel and the right side rear apron got bent in transit. I'll straighten them out, but I wish couriers would be a little more careful.  The right side grab handle is also bent.

Pete was 'ERE!!   (perhaps 'Pete' reads Observations?)

Who else but RACAL built equipment of this quality?

One somewhat unusual feature of this TX strip is that the sideband filters are mounted outside the cabinet on the rear apron.  The transmit strip is built on a fine quality sand casting  with bays to hold the various PCB and fitted with individual bay cover-plates. The topside as you can see, sports another casting carrying PCB's while the PSU components are mounted on the flipside of the larger casting.  The front panel can be completely detached after two connectors are parted and a few fixing screws removed. The little white things mounted on the PCB's are component carriers, used to mount small components vertically while providing mechanical support.   The logic used in this TX driver is mainly plain old 74XX series ICs. Despite having been dropped and the steel U channel side-plate bent by the courier, this driver worked straight out of the box.  I'll straighten the bent bits in our engineering workshop. It's a rather heavy unit as you'd expect.  Power output was confirmed as 20 and 200mw. Like it's stable-mate the RA1772, the little panel meter serves a multitude of functions from measuring RF power to monitoring the PSU lines.

73 Al.
GM1SXX
 

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