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Hi all,

problem solved: as I said, the counter was counting fine on the low frequency input, but on the high frequency input, it displayed only zeros. The reason was that
a) the -5.2V operating voltage was out of the spec
b) the solder joint between the semirigid coax to the front panel's N connector cracked, thus the semirigid was no longer connected to the connector. I re-soldered and now it counts fine (only tested with 2 GHz so far).

I wonder whether it is possible to replace the ROM. It would be nice to add option 004, the DAC. I have couple of DAC80 here, however, opt. 004 needs a different ROM, unfortunately.

I also read that there was an option 005, which extends the frequency range to 24 GHz. Does someone know what option 005 actually was? was it a different sampler, or something that can easily be changed?

Tobias

________________________________
From: hp_agilent_equipment@... [hp_agilent_equipment@...]
Sent: Wednesday, October 18, 2017 04:37
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: 5342A: blown sampler?



Hi,

Your measurements with the diode mode suggest the sampler is OK, digital meters don't use the same amount of current to test resistance as older analogue meters and that's the reason you didn't get their readings.


I agree with Steve, you may need to replace a number of the 1826-0371, either on the A8 main VCO, A4 offset VCO or both.


I'd also check the A5 output to see if you're getting drive to the sampler driver and then check the sampler driver A26 itself.


I'd check in that order, check the VCOs are outputting signal, check the A5 to ensure it's outputting a signal to A26 and it should alternate between the two VCOs, then check A26.


To check the sampler driver A26 you really need a spectrum analyser. As most spectrum analysers have a capacitor (DC block) in the front end you need to terminate the A26 module with 50 Ohm and then measure what you see ac ross that with the spec an, if you see lots of harmonics then all is good. You will not see anything (apart from the 325MHz drive) without a dc return for the step recovery diode.


If the A26 is not working that could either be the SRD or it could be U1 on the A26 module - I have seen faulty U1 ICs in the past, most likely due to heat - they run very hot.


For the 1826-0371, you can buy fakes/replicas/copies off ebay or do what I do, I make a small smd pcb with 2 x 2sc3356 transistors, 2 x 100 ohm resistors and a 120 ohm resistor in the emitter lead (all smd components) with pins to fit in the DIP footprint. You'll see the schematic for the 1826-0371 on a number of the 5342A schematics. I've not had any issue with my made up boards yet.


If you find it is U1 on the A5 module I can also give you an alternative circuit for that but it is not quite optimised yet and requires short leads to minimise parasi tics.


Good luck

Greg