[Premium-Rx] Reaction Instruments 696 IF display and MA/COM 388 downconverter

[Peter Ratuschni]

Hello to all,

I do not know if this already has been discussed in earlier times and so here are some informations about the Reaction Instruments 696 IF display. This is a half rack size / 2u crt display for IF signals of 10, 21.4 and 160 MHz.
There are 4 inputs and each of it can be used for all of the 3 input frequencies. There are X,Y,Z outputs for an external display. And a remote sweep input - but I did not try this so far. All signal connectors are BNC type. The crt has a size of 1" x 3" and is shielded. 24V/1A has to be supplied to a connector on the rear. There are knobs for sweep rate and width, sweep fwd/rev/rmt, LIN/Log display, marker and the usual ones like gain, focus etc.. 

The whole unit is heavily built and it probably wins the number of screws price in it`s class of size. I counted more than 250 srews for outer and inner covers.

@Terry: If you want I could send some fotos from in and out. (You might have already seen this unit on the internet.) I found the brochure of the neat 695 on your site, thanks! 

Maybe it is worth to also discuss the MA/COM 388A downconverter. The 388 was sold very often and I guess the 388A still is. It`s datasheet can still be downloaded from a distributor's website. It works with input frequencies from 10 to 250MHz. There are 3 inputs for standard IF signals an a tuneable input. I made some experiments with this unit which has the extended bandwidth option, which means that output signal frequency can be as high as 50MHz (and so the bw), instead of 20MHz. I found it quite sensible, so that it can work directly with an antenna as input (at least in my area). A nice option is to downconvert the air band and with a subsequent receiver or demodulator you can hear more messages without tuning here and there (I first thought that this results from overloading the rcv/demod input, but I guess that I should have seen this on it`s display (hp8922) - I know the 8922 itself can be used directly as a rcv, but I wanted to test what happens when a broad frequency range is first downconverted before undergoing selection by tuneable or fixed filters). I tried the same with FM radio signals from a nearby transmitter - here I had to use a crystal filter (21.4MHz/250KHz) after the downconverter to get good results. (It basically worked without the filter and with tuning the subsequent 8922 to the different stations, but that sounded worse.).   


best regards
Peter