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Re: inner working of the hp8656 attenuator

 

¿ªÔÆÌåÓý

Dear Syd,

Check for the obvious first- was the generator working and then failed in this way, or was it like this when you received it.

If the latter, a common reason is that someone transmitted into the generator with enough power or duration to damage the limiter/attenuator.

Start your checks from the output socket inwards.

Good luck.

Alwyn

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________
Re: vector voltmeter

 

At the Newbury rally I came across someone buying up bits of 8405As. He said that he wanted them because he repaired them.? Unfortunatly I didn't manage to get the details.

Had I arrived at the stall I would have bought some of the bits.

Paul G8AQA
Re: Hp 8664A

 

On Tue, Dec 1, 2020 at 08:01 AM, george edmonds wrote:
Hi Roy

There is no service manual for the 8664A, just an assembly level manual which is on the Keysight web site.
that's still a service manual and that's all you need really. It has block diagrams and self tests and special functions for diagnostics



The best I can find is that the 8643 is similar or identical and Artek has the CLIP for that.
8643 has very little in common with 8664a specially the microwave loop which is the subject these error codes
does not even exist in 8643





Good Luck with it

George G6HIG Dover UK
On Tuesday, 1 December 2020, 12:38:45 GMT, royajohnson2 via groups.io <royajohnson2@...> wrote:
?
?
Hi
does anybody have a copy of the service manual for a 8664A
thanks Roy
Re: Hp 8664A

 

Hi Roy

There is no service manual for the 8664A, just an assembly level manual which is on the Keysight web site.

The best I can find is that the 8643 is similar or identical and Artek has the CLIP for that.

Good Luck with it

George G6HIG Dover UK
On Tuesday, 1 December 2020, 12:38:45 GMT, royajohnson2 via groups.io <royajohnson2@...> wrote:


Hi
does anybody have a copy of the service manual for a 8664A
thanks Roy

Re: Hp 8664A

 

Hi
does anybody have a copy of the service manual for a 8664A
thanks Roy
Re: 9122 and 9122C - HPIB Connected DiskDrives - Scrap or save?

 

On Mon, Nov 30, 2020 at 04:14 PM, ulf_r_k wrote:
Ulf Kylenfall
SM6GXV
I have a cousin in Gothenburg. That is quite close to you?
Re: 9122 and 9122C - HPIB Connected DiskDrives - Scrap or save?

 

I could give them a new home and I am pretty close (?land) so shipping should not be that expensive. As you might be aware do I have an disk emulator that I created, but having? areal disk to compare with could be cool. Please drop me a mail offline
Re: inner working of the hp8656 attenuator

 

My primary concern is troubleshooting a 23 dB output error in this unit!

I think the 1 dB steps are done in the A6 pin modulator circuit controlled by the ALC circuit. Maybe if that circuit were screwed up this could be the cause of my 23dB output error.? I've heard that the reverse power circuitry can produces bad output level results like this, so can this be of concern since my unit has about a 23dB wrong output level. After doing a manual attenuator check I see that all the attenuators in the A9 assembly are working.? So I have been trying to get the covers off the input circuitry to A9 to further ascertain that the problem is in the circuitry feeding the attenuator.
Syd
Re: Agilent 54831M

Bostonman
 

If I remove the RAM, I get a repetitive beep about every 2-3s.

As for the VGA being enabled, it shows the initial stuff (but that's DOS) and in the past has shown the blue screen of death when trying to boot from the XP CD.

Also, the monitor shows a green LED indicating it has video.

Arrggg, I'm so disappointed. I thought this scope was the deal of the century since I got it so cheap. I was told about the two "broken" channels before buying it, but figured I have two good ones and/or four if I don't use the 50ohm mode.
Re: Agilent 54831M

 

yeah, it looks something is wrong with the electronics/hardware of that motherboard

I have a couple of suggestions:
1- try ti re seat the CPU itself. just take off the heatsink, remove the cpu and plug it back in?
maybe spray flush some IPA into its socket and then blow with compressed air or just let it sit to dry
no need to re apply thermal paste but if you have fresh one, it's better to do so. Re seating cpu had helped me
looong ago with some intermittent boot problems when I was building PCs...

2- read the mother board manual and try to connect a small speaker (or even headphone or somthing) to the speaker pins
on the board to try and look for BIOS beep codes. This thing produces some kinda sound when it boots and?
that can be of a big help sometimes. How many beeps, how long? etc....

are you sure the VGA port is indeed working and enabled? I mean you did have video on that VGA port before, right?
Re: Agilent 54831M

Bostonman
 

I disconnected everything except the 20-pin power connector, uprocessor fan/temp, and tried powering the mother board with both the Agilent supply and the power supply in my old PC. Also, I tried both the original RAM stick and the one I just bought; and in two different slots.

In both cases the mother board powered without the need to pull down the green wire. After the initial screen, I don't see any video. Maybe I should let it sit longer, but I let it sit a good two or three minutes.

I also tried with the keyboard connected (ps2) and pressed DEL several times, however, I'm unable to access BIOS. I thought maybe removing the CMOS battery would help, but it didn't make a difference.

It seems the mother board is the culprit, but it seems odd since this once worked (with the exception of channel 2 and 3 not working in 50ohms, but measuring 50ohms to ground).

On a side note, in all cases (or at least it seems), the LED on the mother board labeled 5V standby is always illuminated.
Re: Hp 8664A

 

Hi
thanks very much I will have a good lock this week
roy
Re: Hp 8664A

 

module #2 is the microwave loop assembly (A11 module) that's as much as I can tell from memory
it could be that the microwave loop needs adjustment and the DACs are hitting their limits at the moment
or it could be other problem
if you run the instrument diagnostics as per service manual and do the follow up tests (specially the special function
that lets you check the MUX values on that module and compare with the expected values in the service manual)?
usually can narrow down the issue.?
In the end you might as well get to component level troubleshooting but first it should be established which module is causing the unlock?
VNA calibration kits - prices likely to rise considerably to Europe within a couple of weeks

 

For anyone considering purchasing one of our calibration kits, be aware that the price to customers in the EU are quietly likely to rise around 20% soon, as the UK leaves the EU, You will get hit with import duty / VAT, which you don't currently need to pay. But it will be conditional on orders being received in Europe before the end of the year.

SMA kit

N kit




Dr David Kirkby Ph.D C.Eng MIET
Email: drkirkby@... Web:
Kirkby Microwave Ltd (Tel 01621-680100 / +44 1621-680100)
Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT.
Re: Hp 8664A

 

Hi
When I switch it on it comes up with this error? 2.404.312 or 2.468.312
Roy
Re: Hp 8664A

 

well I think there were several modules in that loop so you should first run the diagnostics and see what codes you get
that will narrow it down a bit
otherwise the loop covers A10, A11, A13,A14?
Re: Hp 8664A

 

hi
Thanks for the quick response it does have a output but its not on the right frequency
What would be the best module to have a look at First
Roy
Re: Hp 8664A

 

the main PLL loop is unlocked (it covers the Fractional N divider and YTO driver and PLL)
do you get any RF output? at what frequencies it fails?

run the instrument diagnostics to narrow it down...this thing is a beast to repair so be ready!
but unlocked PLL to my experience is usually repairable
unlike the ALC errors which most of the time means the custom microcircuit is bad?
Re: 9122 and 9122C - HPIB Connected DiskDrives - Scrap or save?

 

¿ªÔÆÌåÓý

Hi,

check on these people:


With best regards
Tam HANNA 

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
On 2020. 11. 30. 20:58, ulf_r_k via groups.io wrote:

Well. I am in Sweden. I would gladly give them away rather than scrapping them but the shipping charges
makes overseas transport to expenceive.

You can imagine how I feel when I see adverts on instruments
that would fit perfectly in my little RF-lab,
only to se "Local pick-up only" or "Continental US only".

I will try to see how much a shipping within the EU would be.

"I'll be back"

Ulf / GXV
Re: 9122 and 9122C - HPIB Connected DiskDrives - Scrap or save?

 

Well. I am in Sweden. I would gladly give them away rather than scrapping them but the shipping charges
makes overseas transport to expenceive.

You can imagine how I feel when I see adverts on instruments
that would fit perfectly in my little RF-lab,
only to se "Local pick-up only" or "Continental US only".

I will try to see how much a shipping within the EU would be.

"I'll be back"

Ulf / GXV
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