HP3577A 5Hz-200Mhz VNA Teardown

[Berni]

I had a quite time getting the same CRT module out of my HP 4145B Semiconductor Analyzer.

That had most of the screws in the silver front bezel, as far as i remember two screws in the front top and two in the front left side (Its those i missed). Some of these are under decorative stickers and some of the identical looking screws found in there actually hold the bezel to other parts, but the ones around the screen hold the CRT module in. Once those are out its just a matter of two or three easily accessible screws in the back, before the whole thing slides out forwards with next to no force. Some screws around the CRT module are not required to be removed because they just hold the CRT module itself together.

But perhaps this instrument has extra screws.

[precaud]

Yeah, the 3577A is the only one I've seen that has an extra bracket at the bottom rear of the 1345A for attaching to the "shelf".

EDIT: OK, sounds like you got it...

[bson]

The NewScope-5 is fantastic.  LOVE IT. 

Applied my advanced arts & crafts skills to the foam liner installation:



LCD mounted in bezel:



Power-on smoke test before closing it up.  I had actually forgotten to plug in the main power cable, so good thing I checked...  Also adjusted the focus trimmer to pick a color scheme.  Also had to move the scan direction jumper to get the image right-side up.



Back in use:



I had planned to replace the fan while I had it open, and I did detach the fan, but couldn't get it out without removing the BNC jacks and I didn't want to go there.  It's possible I could have yanked it out with force.

The ONLY thing wrong with the NS5 kit is I didn't get it a long time ago!

[precaud]

Man, that is SO nice... so much easier to read... congrats.   

[sixtimesseven]

I run the fan mentioned in the first post, so far no problems with it. It is still loud but, but before it was unbarable, now it is about on the level of my HP8753D which is acceptable.
We have a sound pressure meter at work, I will try and remember to borrow it to give you some data.

[sixtimesseven]

Yeah so much better than the CRT!

I have to say the Newscope Displays are top notch, very nice blacks. Much better than my 20 Dollar Aliexpress LCD I hacked on to my 8753 ...
But dam the kits are expensive!

[Berni]

Yeah the price of these Newscope displays is the reason i haven't put one of them in  my HP 8566B. They look great, but the price of it is hard to justify when my CRT still works fine.

[precaud]

Just a general note to 3577A owners.

Should you ever want to go through the adjustments procedures and calibrate your unit (especially the input boards), use the procedures given in the 3577B service manual PDF. The adjustments in the 3577A manuals, both printed and PDF, are incomplete and in the wrong order!

This is true of all revisions of the 3577A service manual.

[rx8pilot]

Just a general note to 3577A owners.

Should you ever want to go through the adjustments procedures and calibrate your unit (especially the input boards), use the procedures given in the 3577B service manual PDF. The adjustments in the 3577A manuals, both printed and PDF, are incomplete and in the wrong order!

This is true of all revisions of the 3577A service manual.

This is an awesome addition to this thread. As an owner of an A model - I think this saved me a pile of time. Thanks.

[Calvin]

Hi,

now that my 3577A is working again, I´m looking for an affordable S-Parameter Test Set or an alternative, since the prices + shipping of these sets are higher than what I paid for the VNA   
Just a Q regarding the connectors of the subassemblies in the 35677 S-Parameter Test Sets.
It looks as if the connectors to and from the coaxial relay (33311B) and the directional Bridges (3577-66502) are all of the SMA female type.
The ´Port1´ and ´Port2´ outputs of the two bridges are of N-type but it appears to me that rather they feature SMAs with an SMA-to-N adapter screwed on.
Is that true?
I assume one doesn´t need additional D-Blocks when a (original) 35677 is connected to the VNA? Are those only required for useage of the VNA alone?
As alternative DIY-Setup ... would those cheap chinese/ucrainian 0.1-3000MHz bridges be suitable (with their Ref-otputs terminated into 50R)?

regards
Calvin

btw. found prices in the 1990 HP catalog - 3577A: 25,570$, 35677A: 4,100$ - which would be ~52,000$ and ~8,400$ respectively. What a whopper

[rx8pilot]

btw. found prices in the 1990 HP catalog - 3577A: 25,570$, 35677A: 4,100$ - which would be ~52,000$ and ~8,400$ respectively. What a whopper

Lol! I paid $200 for mine in non-functional condition. Spent about $15 on parts and about 5-6hrs, now it works perfect. Bargain!!!

[miken]

The ´Port1´ and ´Port2´ outputs of the two bridges are of N-type but it appears to me that rather they feature SMAs with an SMA-to-N adapter screwed on.
Is that true?

It's an actual N bulkhead connector, with threading to attach it to the front panel. The back end necks down to a smaller diameter and solders directly to the board.

I assume one doesn´t need additional D-Blocks when a (original) 35677 is connected to the VNA? Are those only required for useage of the VNA alone?
As alternative DIY-Setup ... would those cheap chinese/ucrainian 0.1-3000MHz bridges be suitable (with their Ref-otputs terminated into 50R)?

The bridges have DC blocking capacitors. They are pretty simple inside, caps, resistors, balun. You could probably make your own without too much trouble.

There is a measurement of the cheap bridge here: https://www.eevblog.com/forum/testgear/test-results-for-the-e-bay-rf-bridge-in-an-enclosure/msg1627738/#msg1627738
Though I will say that I measured one once and got worse results at the low end, better at the high end. Not sure if my mistake or if quality varies.

[Calvin]

Hi,

thank You so much.
Yeah, the 35677A circuitry appears simple ... power splitter, 12dB-attenuator, coax relay, two directional couplers, a couple of some semi-rigid cables, and switch logic, besides loads of nude virgin breath  -aka known as used air- in a way tooo large casing. 
Do You happen to know if the coaxial relay connectors are SMAs?
I ordered a pair of 33311Bs and also a pair of the (orginal) Bridges from transverterstore.com (just to be sure that I don´t get some crappy chinese fake something).
It´d be nice if it could be wird solely with SMA cables.

regards
Calvin

[miken]

Yes, I believe the switch is also SMA. I bought a broken 35677A myself. Turns out it had one broken semi-rigid, typical solder joint break. One bridge measured really bad, so I replaced all the caps with SMD, but it turns out it was just the adjustment screw in the bottom... My future project is to build a VNA inside the 35677A box, plenty of space as you say 

[precaud]

I finally replaced the fan in my 3577A. I found a couple of these in one of my parts boxes and put one in:

https://www.mouser.com/ProductDetail/ebm-papst/W2G107-AD03-13?qs=RViDcLGODe0xrlbxBmPSjg%3D%3D

Result: Noise level reduced by half or more, down to a bearable level. Very worthwhile. And no noticeable drop in airflow. In fact, it feels stronger to me.

The original fan is noisy even unmounted.

[Fretec]

Same fans can be found on Ebay for a good price: https://www.ebay.com/itm/303227534315 (not affiliated or something)

[precaud]

Nice price, until I saw the shipping cost. Another eBay seller WAY overcharging to ship...