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HP 70K/HP 70000 Modular Measurement System Thread

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ruhnet:

--- Quote from: Marian.MQH on May 20, 2021, 10:30:59 am ---  HP 70601A RF ( 0...26,5GHz )
  HP 70906A Preselector ( 50k...26,5GHz
  and  70900A, 70903A, 70902A, 70004A 70311A

   I intend to improve its parameters by adding HP 70620A (Preamplifier 2-22GHz).
   My question is whether my HP 70k will work with this type of preamplifier (in its operating range 2..22GHz) ?

--- End quote ---

Marian, I would think it would at least partially work, but your readings could possibly be a bit off, depending on how the 70900 deals with the preamp being in the system. There's not documentation on non-standard configs like that, so it's mostly trial and error to see how it will behave. In general though, the system usually "tries" to work even with non-standard setups, but you sometimes get strange or off behavior.

The 70620 sends gain/flatness information to the 70900 so it can give you an accurate amplitude reading over the full frequency range. Whether or not the 70900 interprets that data correctly in the frequencies below 22GHz with a 70620A depends on how that data is used vs how it is done with the 70620B. I have a feeling it will work correctly, but I have not tried it.

I have a 70908A 22GHz RF section, and a 70600A 22GHz preselector that was intended to go with a 70905A RF section. I tried putting the 70600A in the chassis with my 70908, hoping that I could use the 70600A preselector independently via the tune voltage input. As I mentioned above, the system "tried" to work, but it wasn't a useful result. The 70900B saw the unit, and did not complain about it, but IIRC it blanked the trace below 3 GHz and above a certain range (maybe for the first band of the preselector---I don't remember the details exactly). The tune voltage did control the preselector correctly within one band, but the 70900 would not make it switch bands, since it wasn't paired with a 70905 input section, even though my 70908A is also 22GHz.

But I do not believe there are any band changes or anything like that with the 70620A preamp, just the calibration data as I mentioned above, so it is likely to work, and in the worst case probably just give some amplitude error (the microwave preamp is spec'd at +/-2.8dB over the range from 2-22GHz.) If it did show amplitude errors, you could measure the gain at various frequencies yourself with another instrument, and print out a correction table, or even generate a correction line that you could load in the analyzer and add to the trace to make it display accurately. Give it a shot and let us know how it goes!  :D

Edit: Also, make sure your 70900A has a firmware version late enough (900314 or later) to work with the 70620A.

Marian.MQH:
RUHNET, Thank you for your comprehensive answer to my question. I bought the HP70k (70601A, 70606A, 70900A, 70903A, 70902A) from a recycling company with the intention of recovering the elements - the visual condition of this equipment turned out to be so good that I decided to complete it. In another company, I bought more blocks (700004A, 70311A) and after I made the HP-MSIB cables myself, the analyzer started.
The software version is 900316 (at least this is what the display of the analyzer displays for a moment after switching on). Before mounting the preamplifier, I set its jumpers (ROW and COLUMN).After switching on, there were alarms 2025 and 6010, and when attempting to calibrate 2032. I checked the HF amplifier module outside the analyzer, which works OK. Due to other activities (testing AGC system for Tracking Generator SA FSEB30 R&S, which I made myself), I put off testing with HP70k.I will be grateful for any further advice.
Greetings
Marian

ruhnet:
Hmm, well unfortunately those errors look like either the preamp module is faulty, or that the 70900A is refusing to work with it, since the matching 22GHz RF section isn't installed. The 2032 upon CAL seems like it is wanting to communicate with the 22GHz RF section (probably to combine its flatness cal data with the flatness cal data from the preamp) and of course can't find it in the system. The other two errors are slave module communication errors, so it's either having trouble talking to the 70620 itself, or because of wanting to combine it with a 22GHz RF section.

I guess the way to know which situation is happening (faulty module vs refusal to control) would be to test in a 22GHz system.

But if that isn't an option one thing you could do though, since you have already tested and determined the actual amp is working, is to remove/disable some of the control circuitry in the 70620, and just power the internal preamp itself from the mainframe as a "dumb" accessory. This should let you use it at least, and you could apply amplitude correction to your measurements manually. You could drill a hole in the middle front panel and put a switch to control the path switching relays inside to insert/remove the preamp from the signal path. Or just leave it in the path all the time and connect/disconnect externally with a short jumper like it was intended to have between its output and the RF section.

Marian.MQH:
 Hello,
Thanks for helpful information, as I wrote recently I am dealing with the AGC system for my TG FSEB30 (I have attached a photo of my project).

 After installing 70620A, the analyzer does not work properly. It displays only the trace of 3 ... 6.55GHz (LO range) with the signal at 3.61GHz (-2.57dBm) and does not react to the signal applied to the input.
It is not possible to check block 70620A in another analyzer, I am not sure if such a device is in Poland.
It will remain a modification of block 70620A, getting rid of the signal pins (leaving only the power to the amplifier and relays) and, as you wrote, mounting the switch on the front panel.It may not be "elegant", but it will sometimes allow you to take measurements.
You mentioned previously about problems with the preselector, fortunately my 70906A analyzer works OK - I can't imagine measurements without it due to the large number of false signals (low IF frequency).
Thank you very much Greetings.
Marian

Paul B:
Hi all
My name is Paul Bicknell and I live on the south coast in England

Although I am new to this site I have been playing with HP 70 K for a few years now
And I might know a few of you from the Groups IO site 

I am presently trying to decide on the replacement capacitors to rebuild the power supplies in
3 off 70900 A local oscillators that have failed

My next project is to modify a 70900 B local oscillators to have
The latest firmware and 512 K of memory upgrade
also the receiver personality could anyone please help me with the following

Dear PQUADRAT  Could I take you up on your offer of how you did your upgrade
Also could you please let me have the make and part numbers of the sockets you used
For your upgrade of the firmware memory ?
Also What equipment do I require to program the firmware / ROM chips for the 70900B ?

Could you also explain the memory upgrade hopefully a picture before and after the 512 K memory upgrade

I have a 8705A 512K memory card how can I find out what is on it  ?
Can anyone help me with putting the receiver personality onto the 8705A 512K memory card ?

Regards Paul   PS sorry about the long list

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