Author Topic: Cloning the HP3325A Option 002 - HV Output (Read 15669 times)

Jay_Diddy_B · « **on:** April 07, 2019, 02:37:20 am »

Hi,
This thread is dedicated to cloning the high voltage option board A8 used in the HP3325A option 002 HV Output.

I have successfully cloned this board in the past, but I have lost the files.

Here are pictures of my clone:

I have attached the section from the manual.

I remember entering the schematic from the manual and then placing the components in the same place and orientation as the HP original. I used the net list as a guide as where to route the tracks.

I used MPS8099 (NPN) and MPS8599 (PNP) for all the small transistors. Q1 on the original is a dual transistor. I just used two MPS8099 glued together.

I used MJE243 (NPN) and MJE172 (PNP) for the output transistors.

Regards,

Jay_Diddy_B

TERRA Operative · « **Reply #1 on:** April 07, 2019, 04:00:46 am »

I think I'll do a similar thing re. placing the components to replicate the HP layout, with maybe a few little alterations as I find along the way to neaten the routing etc.
I have been having a look at cross referencing of the silicon so far.

So far I have this (Subject to change):
(Part numbers from Digikey)

Dual NPN Transistor 1854-0475 (supersedes to 1854-1030 and 1854-0688) - MAT01GHZ + heatsink 323005B00000G
All PNP transistors - 2N3906
15V Zener 1902-3205 - 1N5245
30V Zener 1902-0244 - 1N4751
Switching Diode 30V 1901-0040 - 1N4148
Switching Diode 80V 1901-0050 - 1N4150

Other parts so far:

RCA Socket - RCJ-021
TO-220 Heatsink - V2109B
3-Pin Connector - Molex KK5273 Series - 0009652038
Bridge Rectifier MDA202 - KPB204G

Jay_Diddy_B, what did you use for the board interconnects? I am looking for short pre-made 90^o RCA cables but I haven't turned up anything with a quick search yet..
Also, what are the dimensions of your board?

Jay_Diddy_B · « **Reply #2 on:** April 07, 2019, 09:59:50 am »

Quote from: TERRA Operative on April 07, 2019, 04:00:46 am

Jay_Diddy_B, what did you use for the board interconnects? I am looking for short pre-made 90^o RCA cables but I haven't turned up anything with a quick search yet..
Also, what are the dimensions of your board?

I measured the board that I made:

The holes are 0.250 inches in from the sides. The board is 4.600 x 2.350 inches. (too big for the 100mm x 100mm cheap boards

)

Regards,

Jay_Diddy_B

TERRA Operative · « **Reply #3 on:** April 07, 2019, 12:40:25 pm »

Awesome, thanks.

Yeah, I thought it would be too big for the cheap boards..

Ah well, it's still not tooooo expensive anyway. I wonder if there is anywhere that will do gold plating and also clear or no solder mask to match the old HP style PCB?

Jay_Diddy_B · « **Reply #4 on:** April 07, 2019, 02:34:05 pm »

Hi,

I have put together an LTspice model for the amplifier. I have picked some transistors that I am familiar with in the LTspice library. This is the same as the original HP circuit. I haven't done any tweaks.

I haven't compared these results to the hardware.

I have attached the model.

Regards,
Jay_Diddy_B

TERRA Operative · « **Reply #5 on:** April 08, 2019, 02:27:44 am »

Nice work. I haven't used LTspice before, I should learn it some day..
Is there a spice model for the MAT01GHZ for the dual transistor? I wonder how much of a difference it would make.

Also, that square wave looks a bit nasty, how does it look on a scope from your physical unit?

Jay_Diddy_B · « **Reply #6 on:** April 08, 2019, 03:37:05 am »

Hi,
I am not sure why the LTspice waveform is distorted.

I would not use the MAT01. It is not recommended for new designs (NRND). I think that it is because it is in a metal can.

The main property of the MAT01, matching is not needed in this high voltage amplifier. The voltage gain of the circuit is only 2.

I have good news!!

I have an original option 002 that I was able to compare with my clone.

Original

Clone

Not a lot of difference.

Regards,

Jay_Diddy_B

TERRA Operative · « **Reply #7 on:** April 08, 2019, 04:25:27 am »

Well, that's good news that the MAT01 isn't needed, that will certainly save a good few $$$ and make future builds easier too.

Can you post a few photos of the original HP option board? I want to see it all close up.

Jay_Diddy_B · « **Reply #8 on:** April 08, 2019, 04:30:55 am »

Quote from: TERRA Operative on April 08, 2019, 04:25:27 am

Well, that's good news that the MAT01 isn't needed, that will certainly save a good few $$$ and make future builds easier too.

Can you post a few photos of the original HP option board? I want to see it all close up.

I will do tomorrow, it is very late here in Toronto.

Regards,

Jay_Diddy_B

Jay_Diddy_B · « **Reply #9 on:** April 08, 2019, 11:24:22 am »

Hi group,

I have taken some photographs of the original board.
The board is slightly smaller than the one I made. The dimensions are 4.500 x 2.25 Inches. The fixing holes are the same.

I did notice a few differences:

All the mounting holes are grounded on the original.
There are ferrite beads on the base leads of Q4 and Q5.

Here are the pictures:

Regards,
Jay_Diddy_B

TERRA Operative · « **Reply #10 on:** April 10, 2019, 01:16:31 am »

I just finished drawing up the schematic in DipTrace.

Next step is to start laying out the PCB.

[Edit: Fixed schematic]

Jay_Diddy_B · « **Reply #11 on:** April 10, 2019, 02:43:41 am »

Hi,

I have had a quick look at the schematic.

1) R10 should be 3.6 $\$\Omega\$$

2) Q14 should be a NPN power transistor MJE182 or similar
HP used MJE223

3) Q15 should be a PNP power transistor MJE172 or similar
HP used MJE233

4) C9 should be 22uF 50V Electrolytic capacitor

5) Most of the small signal transistors need to be more than 40V

1853-0036 was selected from 2N3906 (probably for Vceo >60V)

1853-0042 is a 50V PNP transistor

1853-0020 is a 25V PNP transistor

I used MPS8099 and MPS8599 on the board I built.

Regards,

Jay_Diddy_B

TERRA Operative · « **Reply #12 on:** April 10, 2019, 03:52:59 am »

That'll teach me for doing it at 3am...

I'll make a revision tonight, maybe before midnight this time.

TERRA Operative · « **Reply #13 on:** April 10, 2019, 12:24:08 pm »

Ok, I fixed up the schematic and reuploaded it in my post above, except I still am looking at easy to source transistors.
The MJE243 and MJE172 are easy, but Digikey doesn't have MPS8099 and MPS8599 as they are marked as obsolete, Mouser has them though, so it should be ok.

I wonder if the KSC945 (NPN) and KSA733 (PNP) would be ok substitutes?

vindoline · « **Reply #14 on:** April 10, 2019, 12:27:33 pm »

Looks like a great project! I have an HP3325B - I suspect it would use the same board. I'll have to check.

LazyJack · « **Reply #15 on:** April 10, 2019, 01:01:00 pm »

Yes, the B version uses exactly the same board. It has the same part number.

Rollin Hand · « **Reply #16 on:** April 11, 2019, 07:17:21 pm »

Are this boards for sale?
Thanks

Neomys Sapiens · « **Reply #17 on:** April 12, 2019, 12:30:28 am »

On the topic of the MAT01: even if this 'supermatch pair' is not really needed, a double transistor might be beneficial to the application. Some that are a bit easier to source: MD8002 (Mot), 2N4045, 2N2915, BFY83, SL301L, although I haven't checked their respective suitability yet.

TERRA Operative · « **Reply #18 on:** April 12, 2019, 01:03:17 am »

Quote from: Rollin Hand on April 11, 2019, 07:17:21 pm

Are this boards for sale?
Thanks

I'll release the gerbers and source files (if anyone else uses DipTrace) when they are finished and I'm sure I'll end up with a few spare boards when I get mine made that I could send to people who want one.
Maybe I can order a few extra sets of parts too and send them out as a kit for people to solder together themselves?

Quote from: Neomys Sapiens on April 12, 2019, 12:30:28 am

On the topic of the MAT01: even if this 'supermatch pair' is not really needed, a double transistor might be beneficial to the application. Some that are a bit easier to source: MD8002 (Mot), 2N4045, 2N2915, BFY83, SL301L, although I haven't checked their respective suitability yet.

Cool, I'll take a look at thoise suggestions and see what matches up.
Failing that, using superglue to marry a somewhat matched pair of transistors could work in a pinch.

VK5RC · « **Reply #19 on:** April 12, 2019, 01:17:59 am »

Thanks for the post, @Terra if you are ordering boards and components and can easily add another set - I would put my hand up for one set of both parts and pcb.
Rob
VK5RC

Jay_Diddy_B · « **Reply #20 on:** April 12, 2019, 02:35:20 am »

Hi,

The mismatch in the input transistors Vbe, multiplied by the gain of the amplifier (x2) will appear as offset on the output voltage.

I will measure the offset voltage on my clone versus the original board.

I have been playing with the amplifier in LTspice. I believe that it can be made to be better than original design.
It is still a work in progress, but I have attached my latest LTspice model. I have removed the protection circuit for now. I will put it back at the end.

This version has a slew rate of 1600V/us.

I have made the input stage symmetrical and changed the output transistors. C2 and C3 are trimmers used to optimize the waveform.

This circuit could be used with other function generators to boost the output voltage.

I have attached the LTspice model.

Regards,

Jay_Diddy_B

TERRA Operative · « **Reply #21 on:** April 12, 2019, 05:27:17 am »

Quote from: VK5RC on April 12, 2019, 01:17:59 am

Thanks for the post, @Terra if you are ordering boards and components and can easily add another set - I would put my hand up for one set of both parts and pcb.
Rob
VK5RC

Yeah, I'll probably make a batch of 10 or so to start.
Whichever design we end up making, I'll put together a bunch of kits. I'll wait a bit to see how Jay_Diddy_B's design goes and with his permission, I'll get something put together unless he wants to sort it out for his design.

TERRA Operative · « **Reply #22 on:** April 17, 2019, 02:25:27 pm »

PCB layout V1.0 so far....

I went 4-layer as it greatly simplified layout and I have never tried 4-layer before so I figured why not?

The components are laid out pretty much the same as the original, the traces are adjusted as needed.
It'll change a little when I finalize which transistors will be used, but it's mostly there.

Let me know if you see any obvious mistakes or tweaks I should do.

TERRA Operative · « **Reply #23 on:** April 19, 2019, 01:55:00 pm »

Latest picture.

Lots of little tweaks and stuff to make sure stuff fits. 99% done now.

SilverSolder · « **Reply #24 on:** April 20, 2019, 01:13:54 pm »

Quote from: TERRA Operative on April 08, 2019, 02:27:44 am

Nice work. I haven't used LTspice before, I should learn it some day..
Is there a spice model for the MAT01GHZ for the dual transistor? I wonder how much of a difference it would make.

Apparently there is no spice model for MAT-01. Analog has in the past recommended using the model for SSM2212 instead, which is available.

https://www.analog.com/en/license/spice-models?mediaPath=media/en/simulation-models/spice-models/SSM2212.cir&modelType=spice-models

LTSPICE does have the MAT-02 in its standard library, it may be close enough (or an alternative).


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Author Topic: Cloning the HP3325A Option 002 - HV Output (Read 15669 times)

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