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IFR 1200 SS

I am no longer active in this hobby for the foreseeable future. 
I will no longer maintain or update the website, but I will leave it accessible to the web for as long as possible (years).


IFR 1200 SS
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IFR 1200 Super S Restoration

In 2004 I picked up a IFR1200 Super S in a trade deal. This is the upgraded version of what might be the most popular communications service monitor ever made. (I'm not sure why though--the HP8920 was far more functional, and many orders of magnitude more accurate and capable. They were also comparably priced. Go figure. --Well, back to my story...)

The "Super" S is a little more rare than the standard 1200 S. It included a spectrum analyzer, and sweet options like built in cable test, harmonics test and Bessel functions. They came out near the end of the 1200 product life, and they were pricey. This one had been owned by a paging company that I did some work for, and had been used strictly as an over the air monitor to observe signal quality. (Again, a terrible choice for such a task! But, I digress...)

As received, the monitor was in poor physical condition from bumping around inside a Jeep for several years, and was in flaky electrical condition. The antenna input was deaf, and a light breeze would trip a dozen intermittent symptoms.

Main.jpg (110141 bytes)
The restored IFR 1200 Super S



As is my standard restoration style, I start by tearing down the machine and taking pictures of cable connection points and parts placement so I can refer back to them for reassembly. (I scrounged a copy of the service manual for this job, but I would hate to have to read it just to reassemble the thing!) This is followed by cosmetic restoration and a darn good cleaning. As I clean, I repair whatever I find in need of work along the way. Often, and in this case, a good cleaning will fix most troubles found! Of course, tightening or replacing missing screws helps too.

All switches, buttons, connectors and control pots were cleaned. Boards were removed and cleaned, and all sealed modules that had loose covers or missing screws were also cleaned. The attenuator is a weak point on these things, so I disassembled and carefully cleaned it... very carefully!

Next comes the cosmetic restoration. All paint was stripped, and all dents in the case were pounded out and buffed for smooth surfaces. Hinges cleaned and tightened, as were the handle assemblies. After the "body work" on the case, I cleaned the surfaces with "Semi-Solve" to remove all contaminates, followed immediately by a light coat of self etching primer so that the paint would adhere to the aluminum. Next, a coat of textured paint gave the correct surface texture, followed by a coat of properly matched paint of original color. Then, as I always do, I bake the paint in an oven on low for about six hours (don't bake after the primer coat!). This hardens the paint and dries it completely--no more finger prints or smudges! All knobs were removed and given the same paint treatment.

The handle was painted with "Krinkle Paint", for that unique textured look of the original handle. All missing or damaged hardware was replaced with original IFR parts, at very reasonable expense I might add! (see: http://www.kgelectronics.netfirms.com/parts.html) The lid latches were in rough shape, so they were replaced along with the lid grommet. I also replaced the rubber feet on the handle--excellent! 


As this monitor had poor sensitivity at the "ANT" port, it was obvious that it had received a little too much RF at some point. The normal suspects are the input resistor, the OVP diodes in the front end, and the first RF amp. (Listed in order of price, and complexity of repair). Fortunately, it was the resistor. Yippie! Other than calibration, all other problems were solved by cleaning.


Unfortunately, the 1200's require some very specialized equipment to properly calibrate, schematics are given in the service manual, but geeze! What a pain. I choose to forgo any procedures that called for the extras, and to simply measure the performance instead. Everything came up roses! Nothing but the timebase needed appreciable adjustment, and I was able to "tweak" the scope and voltmeter settings into cal. As I have a GPS based timebase accurate to 1 ppb, I was able to adjust the timebase with great accuracy. Next I did a thorough test of all functions. The finished monitor meets all specs with flying colors!

IFR-35_1024.jpg (262641 bytes)
Front view, as received -- sans case

IFR-13_1024.jpg (236690 bytes)
Restoration complete


I like having a service monitor that I can rely on when I need it, so this was a nice addition to my work bench. The only problem is that I no longer have much need for a service monitor! I played with it from time to time, and actually used it to tune up a radio once or twice, but it was really just sitting around for most of the time. I thought it was a waste--someone else needs to have this beauty, so I decided that it was time to go. I listed the monitor on ebay and it sold for a good price to a nice fellow in England. He was very happy. So was I.

IFR-33_1024.jpg (202486 bytes)
RF amp from ANT, deaf :(

IFR-34_1024.jpg (105387 bytes)
Ah! the problem was simple!

And now, the Before and After pics


IFR-29_1024.jpg (235022 bytes) IFR-31_1024.jpg (202384 bytes)
IFR-32_1024.jpg (220180 bytes) IFR-30_1024.jpg (217736 bytes)

After... (with an inside view)

IFR-36_1024.jpg (335342 bytes) IFR-02_1024.jpg (182058 bytes)
IFR-04_1024.jpg (185391 bytes) IFR-03_1024.jpg (166477 bytes)
IFR-05_1024.jpg (222537 bytes) IFR-06_1024.jpg (177217 bytes)
IFR-08_1024.jpg (182255 bytes) IFR-07_1024.jpg (206455 bytes)
IFR-09_1024.jpg (223515 bytes) IFR-10_1024.jpg (254300 bytes)
IFR-11_1024.jpg (233698 bytes) IFR-12_1024.jpg (239881 bytes)
IFR-14_1024.jpg (100641 bytes) IFR-15_1024.jpg (158141 bytes)
IFR-16_1024.jpg (151633 bytes) IFR-17_1024.jpg (157203 bytes)
IFR-21_1024.jpg (185149 bytes) IFR-27_1024.jpg (208912 bytes)
IFR-22_1024.jpg (187377 bytes) IFR-25_1024.jpg (211252 bytes)

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Copyright 2008 Bryan's Old Computers
Last modified:
October 16, 2009