开云体育

I have the following manuals available for the cost of shipping from
45409. Most are originals though a couple are good quality copies, and
most are in HP binders.

1. 3585B Operating, Service Vol. 1, and Service Vol. 2 (3 binders)

2. 8712ET/ES and 8714ET/ES Service Guide

3. 8920A, 8920B User's Guide Rev. B and
HP8920B HPIB Programmer's Guide with IBASIC (2 binders)

4. 8901B Modulation Analyzer Operation and Service

5. 8753C User's Guide and Quick Reference

6. 3561A Dynamic Signal Analyzer Operating Manual (probably a copy)

7. 8640B Signal Generator User and Service (original bound version)

8. 8902A Service Manual volumes 2, 3, and 4 (3 binders)

Thanks,
John

From: "Dave Seiter" <d.seiter@...>
To: [email protected]
Sent: Sunday, March 8, 2020 12:03:10 AM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 3456A Problem Solved

Which versions of the 3456A does this apply to?? Or all three(?)
-Dave
On Saturday, March 7, 2020, 08:13:45 PM PST, n4buq <n4buq@...>
wrote:

A few weeks ago, I reported a problem with my 3456A where it would fail at
startup with "--------" on the readout and fail Test 3.? I reseated one of
the microprocessors and the problem seemed to go away.? Since Service Note
3456A-13A states to discard the chip sockets for all three microprocessors
and solder them to the board, I figured the problem was in those red chip
sockets and decided instead to replace them with good quality machined
sockets as I believe others have done as well.

Unfortunately, after replacing all three sockets, the problem persisted so I
started down the troubleshooting steps in the manual and one of the very
first things it says to check is +5V on U13 (one of the microprocessors).? I
was surprised to find that to be at 4.7V or, possibly, a few hundredths
under that.? Since I had replaced all the electrolytics in the power supply,
an off voltage like that was something I did not expect at all.? Checking
that rail at the power supply board, though, showed it to be around 5.1V.

Knowing that Service Note 3456A-14A addresses an issue with faulty grounds
(via some riveted ground lugs), I decided to ensure the In Guard board was
properly grounded so I jumpered one of the GND test points on that board to
one of the GND pins on the power supply board and the meter immediately
started working.? If I remove the jumper, the meter stops in its tracks and
restarting it produces that same "--------" and failed Test 3.

I can detect about 0.5 ohms from the pin that connects to the power supply
and the pin that connects GND to the In Guard board and apparently that's
just enough resistance to drop the voltage low enough to cause the processor
to stop so better grounding is in order.

While I'll probably go with the Service Note's recommendation and replace the
rivets with #2-56 screws, nuts, and lock washers, I'm wondering why it might
not be a better plan to simply route ground wiring from pin to pin as
needed.? I see where that was done from the factory from one or two other
pins and it would seem that a separate, soldered wire might be better off
since tiny screws might tend to need cinching up from time to time to ensure
they're still tight.

Has anyone here performed the rivet replacement?? I suppose I'll stick with
that since it's recommended (and will include a drop of DeoxIT under each
lug as well) but was just curious as to whether a separate wire would be a
better plan.

Thanks,
Barry - N4BUQ

A few weeks ago, I reported a problem with my 3456A where it would fail at startup with "--------" on the readout and fail Test 3. I reseated one of the microprocessors and the problem seemed to go away. Since Service Note 3456A-13A states to discard the chip sockets for all three microprocessors and solder them to the board, I figured the problem was in those red chip sockets and decided instead to replace them with good quality machined sockets as I believe others have done as well.

Unfortunately, after replacing all three sockets, the problem persisted so I started down the troubleshooting steps in the manual and one of the very first things it says to check is +5V on U13 (one of the microprocessors). I was surprised to find that to be at 4.7V or, possibly, a few hundredths under that. Since I had replaced all the electrolytics in the power supply, an off voltage like that was something I did not expect at all. Checking that rail at the power supply board, though, showed it to be around 5.1V.

Knowing that Service Note 3456A-14A addresses an issue with faulty grounds (via some riveted ground lugs), I decided to ensure the In Guard board was properly grounded so I jumpered one of the GND test points on that board to one of the GND pins on the power supply board and the meter immediately started working. If I remove the jumper, the meter stops in its tracks and restarting it produces that same "--------" and failed Test 3.

I can detect about 0.5 ohms from the pin that connects to the power supply and the pin that connects GND to the In Guard board and apparently that's just enough resistance to drop the voltage low enough to cause the processor to stop so better grounding is in order.

While I'll probably go with the Service Note's recommendation and replace the rivets with #2-56 screws, nuts, and lock washers, I'm wondering why it might not be a better plan to simply route ground wiring from pin to pin as needed. I see where that was done from the factory from one or two other pins and it would seem that a separate, soldered wire might be better off since tiny screws might tend to need cinching up from time to time to ensure they're still tight.

Has anyone here performed the rivet replacement? I suppose I'll stick with that since it's recommended (and will include a drop of DeoxIT under each lug as well) but was just curious as to whether a separate wire would be a better plan.

Thanks,
Barry - N4BUQ

7 mars 2020 kl. 10:29 em skrev Kuba Ober <kuba@...>:

?I can chime in as a ME wearing an EE hat :) I see S11 measurement as essentially a shaker table measurement where you are not allowed to touch anything but the interface plane. Imagine a shaker and a load cell + an accelerometer between the shaker and the DUT. Or think of holding a short slinky hanging down from your arm. Close your eyes - you can only feel the interface plane. Shake it in various ways and you get the slinky’s S11 response.

Then stick a load cell with a test mass and another accelerometer stuck to it on the far end, and you get S12. Swap the ends and you can measure S22 and S21.

In one “interpretation”, the load cell measures the mechanical equivalent of current. The accelerometer measures the mechanical equivalent of voltage. In such interpretation (one of many), mass is the equivalent of resistance (I=V*R vs F=a*m). If we let acceleration represent a higher derivative of voltage, you can also find mechanical equivalents for capacitance and resistance. If we let the velocity be the equivalent of voltage, then mechanical damping becomes equivalent to real impedance, and inertia is equivalent to imaginary impedance. And so on, and pardon for mathematical mistakes here. But the gist of it is: you can certainly derive mechanical analogues of electrical circuits. The reverse of it was an actual job description not too long ago, when analog computers simulated mechanical systems and were used to model such.

In an S-parameter test set - and anyone actually knowing what they talk about please correct me - directional couplers and RF switches do the job of separating the energy flow out of a port from the flow into the port.

Circulators are a particularly clever kind of a directional coupler that’s connected back to itself (at least I think of them that way) - the energy can make it all the way back to the 1st port if the ports on the way reflect it “back” - back into the respective ports, but forward in the circulator (there’s an arrow on it that shows which way is “forward”, at least on the few I got). A circulator is the RF equivalent of a lazy Susan :)

The “problem” with bare VNAs is that the S-parameter test set is a separate device, and a costly one from what I gather, yet one without which the capability of the VNA is quite untapped. The “bare” VNA is the RF power source and one or more fancy vector voltmeters. A test set is what connects those up in a circuit that allows a particular kind of very useful measurements (one- and two-port S-parameter measurements). It’s what lets you use those load cells and accelerometers for something useful :)

Best not let the ME ramble too much, though.
Cheers, Kuba

7 mars 2020 kl. 7:41 em skrev Dave McGuire <mcguire@...>:

?On 3/7/20 6:43 PM, David C wrote:
dummy load is a termination with only an input!

If its a parallel connection, yes. Why not a series connection?

VNAs are intended to do "thru' measurments on systems of a
characteristic impedaance (probably 50 ohms)

Uhhh...wha?? No. That's one thing that they can do, but the
assertion that they are "intended" to only do thru measurements is
false. Very, very false.

Some are able to do "single port' i.e. connect the load across the TX
port and read that.

I've never seen a VNA that is unable to do "single port". And from
where I'm sitting right now I can throw a wad of gum at five different VNAs.

Thats not actually
a 'network analysis' because a dummy load is not exactly a network (read
about Fosters networks).

In fact is *is* exactly a network, and performing an S11 analysis on
one is in fact, by definition, network analysis.

Wow. Please read up on what a network is and what VNAs do.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA