IFR T-1200SRA Surveillance Receiver Repair & Troubleshooting 

Thank you for your intriguing comment. It's fascinating to note that the unit seems to be an adaptation of the general 1200S test set. Personally, I've never come across one of these before. Our search for a replacement crystal filter or card is ongoing however, it's heartening to know that despite its issue with USB, the owner still finds utility in it. Once again, thank you for sharing your insights.

@@M0XFXUK Looking a bit closer, I think there are some other changes too - I don't recognize that board with the xtal filters on it you were looking at - IIRC the equivalent PCBA was called "10.7MHz Generate/Receive Assembly" and although it did have some filters on it they were all the smaller HC-18 style and not those larger ones. From the looks of things, the control section, frequency synthesizer and spectrum analyzer are identical though. There was also a Duplex module that was mostly used for testing cellphones and trunked radio, and I would assume that's not present in this unit either.

Hi Houdi, thank you for the comment. Yes it is certainly an interesting bit of kit and if I can get a replacement board/filter to fix it I will make another video and try to make some measurements with it. Thanks again best regards John.

Hi Chris thank you for your comment, I'm glad you found the video interesting.

HI James thank you for you comment. I have seen the IRF1600S service monitors for sale and they look like a great bit of kit and it's always nice to get test equipment that has it's own road case which normally indicates it's been looked after. Yes the new smaller test equipment is fantastic but as you say it costs a pretty penny. Interesting regarding over input power causing problems, that certainly can be an issue but the front end on this looks OK at this stage. I think the main problem is just ageing of the USB IF crystal filter. Would be of great help if you could come up with some service information, this is a similar model to the T-1200SR. Thanks again for leaving the comment.

@@M0XFXUK I will look around and see. It looks familiar. If it's not the exact model it might be close or see if my mentor has more. He was more of a motorola guy when it came to his service monitors. I got the IFR because it was the only one at the time that covered what I wanted for the price. I just lucked out with a really good one this time. I think the first one had issues to start with as it was doing weird things before from the start. The new one has shrugged everything I threw at it.

Hi Andrew, A very good question and thank you for your comment. You know what I should include more explanation and theory in my videos and for that I am sorry and will try to include more in the future. OK so for the final tests on the crystal filters they are not precise readings but only indications. The probe type would not really make any difference as long as you are using the same probe for your tests. Oscilloscope probes are not really suited for making measurements with an SA but in this case we don't need precise reading only an indication. I was looking to see what the signal level difference was going in to the filter was compared to what was coming out. (Insertion loss) To do this you could use an oscilloscope or an AC volt meter that could measure around 10MHz. I had a known good LSB filter so I could use that as a bench mark and the USB filter had considerably more loss than the LSB filter. So as for narrow and wide probes that would not make any difference as that is not tying to make accurate measurements. I hope this has been of help and please feel free to ask more questions and I will do my best to answer. Best regards John

@@M0XFXUK thanks for the detailed answer, , i liked the little feedback loop you made out of the aligator clip( from your sig gen) that caused feedback when near that crystal, which is the reason i asked you about the Tiny SA which gave me the idea, ATM accuracy for alignment is not that important, if i can fault find some of my dead radios with the Tiny SA and the set of SMA probes i bouggt for it i will be a happy chappy. PeaceN73

@@andrewverran3498 Hi Andrew, to be honest I didn't really need the crock clip connected to the probe as the test set was all ready tied to IFR set and the impedance was that high I Imagine it wouldn't have made that much difference anyway. I am not familiar with the Tiny SA but I guess as long as it covers the frequencies you want to observe it would work just fine. 73 M0XFX

Hi Andrew thank you for the comment. Yes they are a very useful bit of kit and can make some precise measurements. I used to use Motorola service monitors back in the early 90's and again they are great bits of test equipment.

Hi Ray, hahaha MI6 I love it 🤣😂 These things are a nightmare to work on as there is little to no service information so I guess IFR are also very good at keeping secrets.