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| HP3577A 5Hz-200Mhz VNA Teardown |
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| sixtimesseven:
Yesterday the postman delivered another boat anchor to my dorstep - A HP3577A VNA with (75Ohm |O S-Parameter Test Kit). Teardown photos: * HP3577A / HP35677A/B S-Parameter Test Set https://www.flickr.com/photos/154275690@N07/albums/72157699120602134 The thing looks a bit beaten and is full of dust but it seems to work fine at first glance. Confidence test fails at item 6a, "Receiver impeadance test" The relays seem to switch fine between 50/1M and the attenuators switch fine for both ranges. Signals comming trough a 20dB attenuator look reasonable as well. Might just be an adjustment problem... Couldn't resist to take it apart a bit. Also the front panel boutons are a bit sticky and I would really like to get them running smooth again. Also I'm probably going to switch out the CRT with a NewScope-5 LCD. Update: LCD ordered and switches cleaned with WD-40 Contact Cleaner. They work great now. I also installed the Sanyo fan (see link below), temperatures at the heatsink stay the same for me and the noise went down from "jet engine" to anoyingly loud oc desktop pc. Update II: New Scope LCD is terrific. Really nice kit and nice LCD. A bit pricy but worth it in my opinion. Interesting links: * Original fan datasheet (Muffin MD24B2): https://www.jameco.com/Jameco/Products/ProdDS/2215478.pdf * Sanyo replacement fan, 39dB: https://www.mouser.ch/datasheet/2/471/San_Ace_120WP38_E-1286779.pdf * Good Service Manual scan for 12.50$, part number 03577-90010: http://artekmanuals.com/manuals/hp-manuals/ * NewScope-5 CRT to color LCD conversion http://simmconnlabscom.ipage.com/store/page4.html * How to clean sticky switches: http://www.rbarrios.com/projects/HPSWITCH/ |
| Johnny10:
I keep losing auctions on this unit. Nice buy. I bought an S-Parameter last month thinking I was going to win an auction on a broken 3577 unit. Nope! I will keep trying. Like your photos |
| sixtimesseven:
--- Quote from: Johnny10 on July 27, 2018, 10:31:14 pm ---I keep losing auctions on this unit. Nice buy. I bought an S-Parameter last month thinking I was going to win an auction on a broken 3577 unit. Nope! I will keep trying. Like your photos --- End quote --- Well the seller put it in for 1499$ so I made him an offer for 900$ and he accepted so :) I cleaned out all some of the dust from where I could get to it, removed the two logic boards and took some more pictures -> See Flickr: https://www.flickr.com/photos/154275690@N07/albums/72157699120602134 I also wanted to backup the firmware but the beancounters at HP have decided not to put in sockets for the ROM IC's :palm: :palm: :palm: Now I'm just waiting on my N to SMA and N to BNC adapters to do some measurments. In the meantime I will probably have a look at the S-Parameter test set... |
| precaud:
--- Quote from: sixtimesseven on July 27, 2018, 10:03:14 pm ---The thing looks a bit beaten and is full of dust but it seems to work fine at first glance. --- End quote --- Well I'm sorry to hear that. I have three 3577A's waiting for me to troubleshoot/repair and I was looking forward to you doing the same in advance :) All of mine have non-trivial issues, unfortunately. (j/k of course... nice that yours mostly works fine!) --- Quote ---Couldn't resist to take it apart a bit. Also the front panel boutons are a bit sticky and I would really like to get them running smooth again. --- End quote --- Easy fixes once the front panel is disassembled. --- Quote ---Also I'm probably going to switch out the CRT with a NewScope-5 LCD. --- End quote --- Huge improvement. As my eyes age, that small crt becomes increasingly difficult to live with. I need to keep a magnifier handy. --- Quote ---Interesting links: -Original fan datasheet (Muffin MD24B2): https://www.jameco.com/Jameco/Products/ProdDS/2215478.pdf --- End quote --- 50dBa ! That's one noisey fan! The fan noise and crt are what keeps the 3577A (and 3562A) off my bench. Lovely instruments crippled with noisey fans and hard-to-read crts. The Achilles heel of the 3577A appears to center around the input relays. That was the major design change between A and B versions, a redesigned front end using different relays. |
| sixtimesseven:
--- Quote ---50dBa ! That's one noisey fan! The fan noise and crt are what keeps the 3577A (and 3562A) off my bench. Lovely instruments crippled with noisey fans and hard-to-read crts. --- End quote --- I probably just install a quiet 12V PC fan with a 24V converter and test with the thermal cam if the 80 CFM are enough without the CRT heating the instrument. --- Quote ---The Achilles heel of the 3577A appears to center around the input relays. That was the major design change between A and B versions, a redesigned front end using different relays. --- End quote --- Do you already have some with that issue? I'm still waiting on Artek to get me the service manual so I have no idea yet what these relays are, but are they replacable at all? |
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