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Re: HP 3325B repair, help needed with Schottky diode

 

Tom, thank You for Your detailed explanation.

But I have a question: How do You get from 18mW dissipation to Pd>800mW ?

And I can not follow Your circuit desription at all.
>In this circuit CR3 and CR4 are used to sum the inputs from the phase comparator and the integrator. The anode of both connect to -15V through a 1k15 resistor. The cathode of CR3 (phase comparator) connects to +15V (26mA). CR4 >(integrator) connected to +15V through 1k ohms (14mA). At 26mA the 1N5711 drops 0.7V for a total power dissipation of 18mW.
In my circuit diagram CR3 and CR4 are connected at the cathode side, and gets its signal from the "ramp down bias current sorce".
CR3 get its signal from Q3/Q4, between +5V and -15V.
CR4 goes to the gate of Q17, and another 0518 schottky diode.
I do not see any 1k15 or 1k resistors.

But I think I found a source for this diode (or a pair): In this very machine! On the power supply board A22 there are also the fast sync and aux outputs, both protected by a pair of 1901-0518. I have never used these outputs, so a not-so-perfect replacement there should not hurt so much as in the frequency synthesis.
Re: HP 3325B repair, help needed with Schottky diode

 

The 1N5711 is a matched part for 5082-2xxx series. The HP datasheet can be found here

It is probably not the same part as the 5082-5509. It seems Broadcom deleted any reference to the part when they took over ownership. So the most we know is:

HP 3325B A21CR3/4
HP-PN 1901-0518 manufacures by HP Div 5 MSD (specification PN)
MFG-PN 5082-5509 (real part PN)
NSN 5961-00-430-6819 (US military universal PN)
70V reverse breakdown voltage
Schottky small signal diode hot carrier


In this circuit CR3 and CR4 are used to sum the inputs from the phase comparator and the integrator. The anode of both connect to -15V through a 1k15 resistor. The cathode of CR3 (phase comparator) connects to +15V (26mA). CR4 (integrator) connected to +15V through 1k ohms (14mA). At 26mA the 1N5711 drops 0.7V for a total power dissipation of 18mW.

Let's figure out what is needed based on the circuit.

The phase comparator and integrator operate at 100kHz. The speed or CR3/4 equate directly to the maximum resolution of the phase comparison and integration. So faster is better.

100KHz or 10¦Ìs = 360¡ã or ¡À1Hz (very bad)
1MHz or 1¦Ìs = 36¡ã or ¡À100mHz or 1 decimal place
10MHz or 100ns = 3.6¡ã or ¡À10mHz or 2 decimal place
100MHz or 10ns = 0.36¡ã or ¡À1mHz or 3 decimal place
1GHz or 1ns = 0.036¡ã or ¡À 100¦ÌHz or 4 decimal place
10GHz or 100ps = 0.0036¡ã or ¡À10¦ÌHz or 5 decimal place (excellent)

This instrument has a resolution of 1¦ÌHz and accuracy of ¡À5mHz. 10ns might work but 1ns is better.

All together you are looking for:
Vrrm > 30V
If > 30mA
Pd > 800mW
Trr < 5nS
Irl = lowest available for best noise performance?

The HP 1N5711 is 70V 15mA 430mW 100ps diode which wouldn't survive the worst case scenario.

1N5711-1/6857-1/6858-1 are 33mA 200mW diodes but are expensive obsolete parts. Oddly Microsemi doesn't specify reverse recovery time or V/s. However 2pF at 1MHz normally equates to 1-5ns which is good enough.

1N4448 100V 200mA 4ns 4pF 500mW 780mV@28mA(22mW)

BAW76 50V 300mA 2ns 2pF 500mW? 1V@100mA(<100mW)

1N4151 same as BAW76 with slightly higher forward voltage drop so slightly higher power dissipation but still well under limits

1N916 same as 1N4448 but with worse power dissipation

1N6638/42/43 150/100/75V 300mA 4.5/5.0/6.0ns 2.5/2.8/2.8pF ~900mV@28mA(25mW)

All of these should work. With BAW76 being the best. If you look harder you can probably find some 1ns or even 100ps diodes?

On Sun, Dec 3, 2023, 6:08?AM factory <bobradios11@...> wrote:
Seems the same problem I have, trying to find info on the 1901-0518. Unfortunately there is almost nothing modern still made in through hole, since Broadcom deleted all the interesting RF parts from HP/Avago;

I've found some 8640B use the 0518 on the A8A3 timebase and A26A4 AGC boards, 0539 is used on the A26A1 power amp board, sadly both are listed as sm sig Schottky, no details given.

David

Re: 11807E Radio Test Software on PCMCIA Cards for the 8920B

 

Robert;
I just sent a Paypal F&F your way. My address is in an e-mail to you.
Thanks Joe

On Thu, Nov 30, 2023 at 12:45 PM, Robert G8RPI wrote:

And if you don't want to DIY, I can do you a Flash card for small fee...

DIY requires a copy of Memory card Explorer, a PC with a PCMCIA slot (including 12V supply unless your Flash card is 5V) and a linear Flash card.

PM me if you want one.
Re: HP 3325B repair, help needed with Schottky diode

 

Seems the same problem I have, trying to find info on the 1901-0518. Unfortunately there is almost nothing modern still made in through hole, since Broadcom deleted all the interesting RF parts from HP/Avago;

I've found some 8640B use the 0518 on the A8A3 timebase and A26A4 AGC boards, 0539 is used on the A26A1 power amp board, sadly both are listed as sm sig Schottky, no details given.

David
HP 3325B repair, help needed with Schottky diode

 

Hi,

I got a HP 3325B, which seems to have seen very little use, no dust inside, and in great shape outside.
Giving all different FAILs at the begining.
First and easy fo find, two radial tantal 15uF caps where short. Seems to happen more likely on items stored for a long time,
so that fits with its overal apperance. Replaced them with new ones, also radial tantal, still available.
But still gave FAIL 23 or FAIL 24, and then FAIL 31.
I was able to limit it to board A21 (top side, left).
THe S/H and integrator part wasn't working at all. It didn' get any signal in, because CR4 was open.
It is a Schottky diode 1901-0518 (HP OEM part 5082-5509).
In my othe 3325B there are dioedes marked HP0518.
In the bad unit they seem to be marked HP0539( very hard to read), for which I could find even less.
Is the 1N5711 a real replacement? Or just "works also" part?

Part is A21CR4.

And suggestions?

Peter

from Hamburg, Germany
Re: Help figuring out my 8648C Signal Generator?....

 

Thanks for the info. :)


I ended up buying an earlier manual to suit my serial number (Which doesn't seem to be available online), so one it arrives I'll scan it in and upload it here and there.
Maybe it'll have some info that I seek...


Jared
IF injector card HP 5062-6241

 

Hello Group, I am searching? this special card to calibrate the IF Section of my HP8593E. Does a GERBER copy of this PCB exist for this card ?, or a photo ?
I do Have a copy of one card produced by DJ1YR HAMRADIO . But I do not have any information about this card anyway.
Best wishes everyone
ON1EV?
Belgium
Re: HP 8116 doesnt reach 50MHz properly

 

If I remember correctly, that's about par for the course on these. It's been awhile since I've played with one. I would recommend you let it warm up for about an hour, and then run through the calibration procedure and see where it stands. Then you can make a decision from there. Check your power supply voltages. These fgens are pretty easy to work on.
HP 8116 doesnt reach 50MHz properly

 

Hello,
i bought an HP8116 in a good condition, working properly except that it can reach about 10MHz and after that the output is attenuated and distorted, in all waweforms.

I didnt make the adjustments yet.
For me, it looks like something is not OK in the output stage, i dont know if the adjusments can correct this distortion and attenuation.

Any way, does anyone have seen something similar?

Best regards
Augusto
Re: Agilent E4406A CPU Board Pulling down the power supply.

 

On my E4406A I changed all the 100k 1206 SMD resistors on the fan controller board (as one of them had gone open circuit) and this cured an issue with the cooling fan running at full duty all the time.

Then some time later the E4406A started to fail to power up. This was again traced to the fan controller board.
On my fan controller board there are also two 150k 1206 SMD resistors and one of these had failed open circuit. Note that it isn't enough to check this resistor in circuit. There will be some circuit resistance there even if the resistor is open circuit. So I had to remove the 150k resistors to measure them.

I replaced both of the 150k resistors (one had failed open circuit) and the E4406A sprang to life again and has been reliable ever since.
Re: HP 8640B Attenuator Repair

 

¿ªÔÆÌåÓý

I believe that Harley Halvorsen devised those hacks while working on the HP355 family of attenuators. He took Art Fong's design and added the compensation that pushed performance to 1GHz (pretty remarkable for something that only uses through-hole resistors). The 8640 team based their attenuator on the 355-family design. I recall seeing pics of the 355's innards somewhere (probably from the hpmemory site). The metal bits seen in Don's pics can be seen in the earlier attenuator as well.

As Don warns, don't "clean up" those metal bits. The attenuator depends on those compensating capacitances to keep the attenuation flat out to 1GHz. And if you ever replace any of the resistors, it is unfortunately likely that flatness will suffer until you tweak it up again.

-- Cheers
Tom
-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
On 12/1/2023 7:18 PM, Don Brown, N3DEB wrote:

And DO NOT touch or move any of the custom tuning materials such as those white wire "pigtails" or the thin metal strips bent around resistors. Don't move anything, and don't let any bumps occur to these parts when cover is off!

These attenuators were not considered field serviceable, I assume needing HP technician test jigs to re tune if any components are replaced.
Re: HP 8640B Attenuator Repair

 

And DO NOT touch or move any of the custom tuning materials such as those white wire "pigtails" or the thin metal strips bent around resistors. Don't move anything, and don't let any bumps occur to these parts when cover is off!

These attenuators were not considered field serviceable, I assume needing HP technician test jigs to re tune if any components are replaced.

I saw some disturbing comments in some forums speculating that those white "pigtails" wire were dangling connection leads from testing at the factory that were just snipped off and left behind! Bad assessment!
Re: HP 8640B Attenuator Repair

 

Two pics, one of attenuator DC injection points in red and other vernier contacts epoxied.

HP 8640B Attenuator 10mA Current Injection Points copy.jpg
HP 8640B Attenuator Vernier Contacts Epoxy Reinforce.jpg

Re: HP 8640B Attenuator Repair

 

You might research on the web, plenty of discussions. It is not a new concept.

Here is one for example:
Re: Agilent E4406A CPU Board Pulling down the power supply.

 

Does it have any MLCC ceramic caps? Those are also prone to cracking and going short.

A $300 thermal camera is really handy to find stuff like this - could be a cap, could be a shorted fet in a switching voltage converter, could be a lot of common things, or it could be something really obscure.
The alternative to the thermal camera is mist the board with IPA - whatever is shorted and getting hot will evaporate the IPA fast - way faster than it evaporates from the rest of the board!


On Fri, Dec 1, 2023 at 3:13?PM Simon WW via <hanzinzl=[email protected]> wrote:
Hello,
I have got an Agilent E4406A VSA that the PSU is hiccupping due to a supply rail overload.
I pulled all the daughter boards and I get down to the CPU board + the front panel and that still causes Hiccup and green LED pulsing on the front panel.
I then pulled the CPU board and the fan control board as I know the unit should power up OK without it.
The PSU comes up Ok and the front panel shows a white blank screen so looks like the CPU board is pulling it down.

I pulled the CPU and started measuring with a DMM around the yellow tant SMD caps to look for a dead short.
Most of them show around 1 kOhm and above bar some that presumably are in parallel over several locations on the board and find they measure around 200 ohms.

Anyone seen / know of any issues to do with the CPU pulling down the power supply?

A little bit of history... I got this unit recently and it would not power on. The orange LED was on but no action from the power switch. Pulling the fan control board made the unit power up Ok and work. I ended up replacing 3 x 100 k SMD resistors after doing a measure. They were open circuit. The unit then worked for a while and was happy I had fixed it until the hiccupping occurred and got to where I am now with the fault.

Any ideas welcome..

Thanks,

Simon
ZL1SWW
Agilent E4406A CPU Board Pulling down the power supply.

 

Hello,
I have got an Agilent E4406A VSA that the PSU is hiccupping due to a supply rail overload.
I pulled all the daughter boards and I get down to the CPU board + the front panel and that still causes Hiccup and green LED pulsing on the front panel.
I then pulled the CPU board and the fan control board as I know the unit should power up OK without it.
The PSU comes up Ok and the front panel shows a white blank screen so looks like the CPU board is pulling it down.

I pulled the CPU and started measuring with a DMM around the yellow tant SMD caps to look for a dead short.
Most of them show around 1 kOhm and above bar some that presumably are in parallel over several locations on the board and find they measure around 200 ohms.

Anyone seen / know of any issues to do with the CPU pulling down the power supply?

A little bit of history... I got this unit recently and it would not power on. The orange LED was on but no action from the power switch. Pulling the fan control board made the unit power up Ok and work. I ended up replacing 3 x 100 k SMD resistors after doing a measure. They were open circuit. The unit then worked for a while and was happy I had fixed it until the hiccupping occurred and got to where I am now with the fault.

Any ideas welcome..

Thanks,

Simon
ZL1SWW
89441A firmware M.09.06

 

¿ªÔÆÌåÓý

Hi,

?

A friend of mine has an 89441A with firmware M.09.06...does anyone have this firmware, because on the Keysight website, the latest downloadable version would be A.09.05.

?
Re: HP 8920B

 

Ok I had to go look at the correct unit this time ?
My 8920B options:
001, 004, 010, 013, 051 & 102

Being new to the HP line what is option 55??
Re: 11807E Radio Test Software on PCMCIA Cards for the 8920B

 

Thanks Robert I just sent payment. What burner do you use I¡¯ve been thinking of getting one but I use windows 11 and i don¡¯t see many that will work??


Drew
Re: 11807E Radio Test Software on PCMCIA Cards for the 8920B

 

I've not seen a copy of the AM test suite. If anyone has a copy I can burn it to a card.

Robert.
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