:IFR-1000s Service Monitor, repairs, by K5JXH
This is the In-Flight Radio Product, circa 1981
It replaces, 5-10 bench intruments, (A SigGen, 100kHz to 1GigHz , a tone generator, and modulator, A scope , A Radio, and a Spectrum Analyzer,)
All fitted up inside a 45 pound box, small taking up very little space. (quality beyond belief and all Teflon wire too boot)
The cool deal with this model , no magic chips, no processors, so no custom VLSI, or Gate array's or ASIC or other magic, chips not made or sold now, all parts inside, 99% can be had, most are easy, TTL is childs play.
The one chip SN76502 is hard to find, but most times lasts forever. (the other 2 high tech parts are the Old 82S141 PROM and DAC-05, in the 2 tone generator board. Mine works but parts are rare.
No NVram chips that have a hidden battery and if goes dead the code is lost for ever, or calibration data to lose, this rig has none of that BS. It is POT rig, chock-a-block full of them.
I bought 2 of these, so I can get one perfect instrument. I will call it a rig from now on, not an instrument or test insturment ,as it truely is...
The first RIG has a dead, main power unit, (SMPS) that hangs off the right rear exposed. (I will get it working later !) The 1st rig has a missing 1200 mhz filter,!
The second RIG,(it is 100% all there)
Tests (first always)
Has 100% GOOD power, all supplies, all perfect and below 20mV Noise, 20khz chopper noise in the SMPS is not present. (well was 10mV) (100mhz scope bandwidth clean)
The 2nd RIG, was not in any attic for 45 years, nor parked in a flooded basement with rodent pee everywhere like #1 above. It is near emacualate as I dreamed.
I always check every power supply first and REGulators, for correct voltages, then noise, if not passing that inspection I fix that first, in all cases. (standard procedure (SOP) in our CAL Lab, of the USN)
That includes hidden REG, many boards on this rig have , 5v and -7v sub regulators, and must all test good. Some are just a Zener and one resistor.. As seen on the 120Khz board ,x2.(times 2)
The only weakness I can see in this design, (besides spectrum analyzer limits) is no crowbar circuits on the rear SMPS, supply, if the regulator there goes nuts, you don't want to blow up vast chips.
The second unit, had a dead left HF, lock lamp , the lamp was good, but I found a RF cable inside that just fell off. #23 ,C23 cable on the so called Hex block right side fell off., killing dead the Sig Gen. (cured) !!
I have a nice DSO O-scope 100mhz, that lets me find this easy, as the RF was dead, and led me there, the cable was well hidden inside, and I missed that, in my careful visual inpection Day1. (need my eye's checked, LOL)
The Hex block is the HF multiMixer with 5 tuned cavities. 1100 to 1900 mHz. The right side is output, and was good, but not connected.
Bam, the SigGen now works and is very accurate too.
If a person needs to see the 1200mHZ signals on a 100mHz scope, one could use a 10:1 PreScaler (1gig to 100mHz) module to do that, I have not tried, but if I had to , I'm sure I could do that. (DIY) (no $15,000. scopes here , ever)
The built in scope works perfectly. (it is only 1 mhz band width) The scope is used with at detector (its own) acting and seen the results of the tracking generator.
I can see my generators pulse on the scope (it has RF detector inside), in GEN mode. (testing the Generators at many different bands now looking for drop out, etc) I can hear my working tone generator.(modulation)
I flip the 2 switches to RECV.
Testing the RADIO side: (there are 2 radio's ,on is the main radio, that runs the speaker and the other is the hidden radio (I.F) deep in side the analyzer board #1.
I am testing the radio now with a small portable whip ant. then latter my ham big gun antenna's. (I also have and SDR whip antenna , not seen below... but is there. now.)
I found 5 super FM radio stations that are over 25kw Power and I can listen to music clear and load, my classic rock is a 50kw station ! under 15miles. (3foot antenna , the speak is crazy loud with Jimmy Hentrix.. Gimme'and F)
Later I will connect my big antenna and listen to WWV and NOAA, and HF hams soon.
One thing I did is mark all modules, with there correct names, for any possible troubleshooting.
There are only 3 pages in the 1000a/s books showing module, locations. (and that topic is not complete at all) I used cable numbers to do my identification of all sub modules. I made this crude ugly page.
Only the 1000s manual has the correct full information. (and the AN/GRM-114 version MIL version for Army/ Navy)
The Below Scope shows signals, now, if those are correct ?, it means the 120MHZ 2nd mixer is working cable 42, and is good into the scopes side board (PCB) spectrum analyzer as seem here.
The 2 analyzer boards have an I.F receiver strip and a simple AM detector diode to drive the vertical deflection amps.
This panel scope is all by its self a receiver, 120mhz in and dual converion to 1Mhz I.F signal then to a rare Texas Instruments SN76502 log amp. and AM detector diode to a buffer and vertical deflection, the 2 boards are really a receiver IF.
So that built-in panel scope is a great diagnostic tool here, if the strong station shows up on the scope but not the speaker , then the 250khz 4th (I.F) is failing or audio detectors/amp. (or squeched heavy or AGC set wrong)
To hear those broadcast stations 2 more boards must work in the , 120 MHZ receiver (3nd/4th,mixers) then 250kHz out to the audio detector board.
The service manual shows no signal scope spec.s (like you'd see back in the DAY, with a "SAM's Photo facts" on say a TV, but sure some levels are is covered in the calibration pages....
I tested all signals from the signal generator from low to 150mhz, I have no need to go higher than that, and no way to even see those signals. (over that)
I did find the scope can see stations weaker that I can hear. Some stations in town are only like 150 watts, many are 1kw stations. (3 foot of antenna is hopeless for these stations)
I only have one failure now and that is the Squelch is dead (but turns off sure). (its on or off and not variable at all) and is on an eazy board to work at, live, to the rear of the speaker is the PCB for Audio.
The dead squelch lamp, (top center marked Level) the lamp works now with 1 LED upgrade to it. The Squelch pot does not, and I suspect the AGC is set wrong, after all it drives the Squelch amp. (It was and is now cured and working)
Lucky me the Mil version 114 has all this CAL stuff in the book in chapter 5, page 117 ( 3 pages) page 5-136 shows where each pot resides on the PCB blue. STEP 9 IS A KEY STEP, to get AGC and Squelch working correctly.
Many calibraration steps use the built in SIG GEN to do many steps, now that is cute , no?
A VIDEO of a Mexican station. (local) click the photo below, to hear the station, this station is so powerful 50kw, @5miles, one could use copper wire , a diode and a speaker and hear it.
Photo of RIG#2 Below I'm in spectrum mode , receive. " ANALY DSPR" knob is max ClockWise so each grad. line is 1mHz. I can hear strong and clear many FM Broadcast stations.
The Level, (squelch) lamp is burned out, LED installed now. Half joking ?,one can use tne HI LVL switch up in GEN mode, and use this as a QRP CW transmitter.... on the HAM Bands.
Photo 1: (It's alive now)
I want the Spectrum analyser to work , real bad and seems to be very much alive. I want to see my transmitter harmonic destortion levels. (the scope analyzer board 2 has calibration steps to get this accurate)
The Antenna jack is only for that, the bottom right is for RF power input.(with DUE CARE per the manual for Watts how long (duty cycles))
The REF out BNC jack, on mine is 10mHz and reads dead accurate with my freq.counter. and scoped the signal is clean.
The main DC power pack behind the transformer is 20vdc raw input all the time, 24/7, line cord hot with 120vac. this is to charge batteries. (so unplug this instrument when not in use!)
My battery is missing and will never be used, by me, so the charger systems are useless, to me.
This rig is TRI-Power operational, (120vac (or240) 12vdc battery or off a running cars, CIG JACK.
My Guts: (rig2) No parts missing here. Keep you's fingers out of the 2000v dc dog house, ok? The bridge Rect. there is 20vdc.
In case you are not aware, 2000vdc is lethal. (as in, "no second chances")
To work on this rig, best is to mark each module with it's name so you don't get, aluminum box befuddled, This RIG I have , has most the electrolyic caps changed out already. (happy feet)
Watch out for cables not connected and worse transposed. That module on the front top rail , check it out carefully. (2nd mixer box) Some modules are not clearly marked, so check them fully.
Best hints of all is to get all books here for all versions of IFR1000 and with them all you will find a missing page that is in the other, saving the DAY. The MIL book saved me in most cases.
Hint 2: is Cable 7 is also called 42... yah !
Links and books.
Books : My Operators short guide, 41page, and The 1000S service book and op's, 351pages (2 books inside 1, nothing better for the 1000s) covers calibration and how to use the intrument, for all tests.
Most books are here. (a Ham site)
The Unit block diagram looks like this. (TIFF format huge)
My horsed up, TIFF photo of the main SMPS supply, as I learn more, I will add to it, (I'm repairing 1 of 2 now) IFR calls it a Duty Cycle board. (it is an outrigger supply pack, for sure)
CRT pull out instructions , my doc, free to all.
version 1. 1-01-2017, this is my personal journal , it is no business here, or authority , so read at your own risk please.