Author Topic: Cloning the HP3325A Option 002 - HV Output  (Read 6115 times)

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Online TERRA Operative

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #25 on: April 28, 2019, 01:40:18 pm »
Ok, time for some small updates.

I recently ordered a bunch of PCB's, so they should arrive soon.
I also just won another 3325A on Yahoo Auctions, with opt 001 (ovenised oscillator) and 002 so I can more easily compare performance between an original board and mine.


Updates to come soonish. :)
« Last Edit: April 28, 2019, 01:54:30 pm by TERRA Operative »
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Online SilverSolder

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #26 on: April 28, 2019, 07:24:48 pm »

Building @Jay_Diddy_B's improved board could also be interesting! 
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #27 on: April 29, 2019, 06:44:47 am »
Yeah, I'll have to get my hands on one when they are done to do a 3-way comparison.

Would be awesome if his could be used beyond the 1Mhz limit of the HP one, but I'm not sure if that'll require reflashing of the ROM on the 3325A motherboard or not?
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Offline LazyJack

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #28 on: April 29, 2019, 07:50:33 am »
It should not require a new ROM. My 3325B is happy to provide any frequency, even is Opt002 is enabled. It seems like that the only change is that id adjusts the output amplitude display, but does not limit the upper frequency.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #29 on: May 03, 2019, 03:42:23 pm »
Alrighty, I got my hands on an original option 002 board.  ;D

Here are some high quality photos of the thing for those who are interested.

Interestingly, there was a shield on this one which I didn't realise was part of the upgrade. It wouldn't be very difficult to make one at all.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #30 on: May 03, 2019, 03:43:11 pm »
Some more shots.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #31 on: May 03, 2019, 03:43:52 pm »
And a few more, showing the shield.


Someone might find these pics useful. :)
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #32 on: May 07, 2019, 12:57:04 pm »
PCB's have finally arrived!  ;D

They are basically a 4 layer copy of the original board. Component placement is as close to the original board as possible, traces are different as needed.
Next step is to solder it together and test that it actually works........

If anyone is interested in one of these, let me know. I have 20 PCB's and I'll supply them as a full kit of parts, with all parts needed to complete one board, including parts to make interconnect wires and screws to mount it in the machine etc.
If I get an idea of who is interested, I'll be able to price up what they are worth for a kit.
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #33 on: May 16, 2019, 02:12:55 am »
Pow! Got the first one assembled.  :-/O  ;D

A few things of note so far:
You may notice a few smaller resistors in the mix, I accidentally purchased 0.25W instead of 0.6W...   :palm: No big deal, just looks weird, I'll fix that with my next Digikey order.
Also, I noticed only after I installed them that the two 10K resistors are specified as 0.1%, 0+-25 Temp Coefficient types... I used 1%, +-50 TC types.. These must be a little critical to stability, but the ones I have will be fine until the next order.
All the rest of the resistors are 1%, +-50 TC types (I can get most of the values for 3yen a piece in Akihabara so yay), which is WELL under the specs in the parts list. Most are specified at 1% 0+-100 or 5% -400/+500.


All the ceramic capacitors I used are C0G/NP0 types too, so good for performance there.


The two axial tantalums have been substituted with axial electrolytics.
For the final version, what do people think of this:
https://www.digikey.com/product-detail/en/kemet/T110B335K035AT/399-11296-ND/4552792
(Rated ESR of 4 \$\Omega\$)

Compared to this:
https://www.digikey.com/product-detail/en/nichicon/TVX1H3R3MAD/493-16279-ND/2539907
(Measured ESR of 2.6 \$\Omega\$)

It's a difference of $2.95 vs $0.55..... I think the electrolytic would be fine, no need to use the tant?


Transistors are 2N3904 and 2N3906, output drive transistors are MJE243G and MJE172G in place of MJE223 and MJE233 respectively.
- MJE223 NPN, 80V, 10MHz
- MJE243G NPN, 100V, 40MHz

- MJE233 PNP, 80V, 10MHz
- MJE172G 80V, 50MHz

Will be interesting to see how they compare at the higher frequencies...


For the dual transistor on the input (The heat sinked can to the right, I replaced the HP part 1854-0475 with two 2N3904's superglued together that I hfe and Vf matched with my ebay component tester.


And finally, I used all 1N4150 diodes (80V) in place of both the 1N4150 and 1N4148 (30V) diodes to simplify things. Diodes are cheap and I ain't penny pinching that much....


Now to wait a few days for some time to start testing. Got family arriving from overseas, so it's time to relax, do some sight-seeing and heat up the barbeque.  ;D
« Last Edit: May 16, 2019, 02:23:24 am by TERRA Operative »
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Offline Neomys Sapiens

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #34 on: May 17, 2019, 05:18:12 pm »
Pow! Got the first one assembled.  :-/O  ;D


The two axial tantalums have been substituted with axial electrolytics.
For the final version, what do people think of this:
https://www.digikey.com/product-detail/en/kemet/T110B335K035AT/399-11296-ND/4552792
(Rated ESR of 4 \$\Omega\$)

Compared to this:
https://www.digikey.com/product-detail/en/nichicon/TVX1H3R3MAD/493-16279-ND/2539907
(Measured ESR of 2.6 \$\Omega\$)

It's a difference of $2.95 vs $0.55..... I think the electrolytic would be fine, no need to use the tant?

I would use the Kemet. Being of hermetic construction, it will keep it's parameters for a long time. Those are not the failure prone Tants! Also Kemet specs are reliable and conservative.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #35 on: May 18, 2019, 12:50:11 am »
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? :D

If you take a look at my boards, you'll see they are gold plated with no soldermask on the top to match the HP boards. They look more brown only due to the internal copper layers from the 4 layer construction.



I would use the Kemet. Being of hermetic construction, it will keep it's parameters for a long time. Those are not the failure prone Tants! Also Kemet specs are reliable and conservative.

Yeah, the lifetime of the tants is impressive compared to the electros. The electrolytics I used are only rated to 2000 hours or so.
What about squeezing a poly or ceramic cap in, seeing as these are only 3.3uf?
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #36 on: May 18, 2019, 05:05:13 am »
Hi,

I used a tantalum bead. The capacitor has about 3.7V applied. The current is low, about 1mA peak, during square wave transitions. The current is lower with a sinewave. The value is not critical. A 4.7uF 10V (or greater) will be okay.

I used something like this:

https://www.digikey.com/product-detail/en/avx-corporation/TAP475K035SRW/478-8986-1-ND/4561852

Regards,

Jay_Diddy_B
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #37 on: May 28, 2019, 01:14:04 am »
Alrighty. Got it working finally.
Turns out that after a bit of head scratching, Diptrace have the Emitter and Collector pins swapped on some of their footprints, or the part I used is swapped from the normal footprint...  :rant:  The usual story....  |O

So that means I have a heap of gold plated 4-layer boards to feed the bin.  :(

Anyway, it's all figured out and ready for a new PCB order, plus I made a few tweaks to placement for clearances and stuff, just minor stuff, a nudge here and a bump there.

Here's the output shown in the pics below.
In order:
- 1MHz Sine (The device seems to attenuate above 1MHz)
- 1Mhz Square
- 100KHz Square
- Close up of the 100KHz square rising edge

Things might need to be poked a bit to reduce that overshoot? Any suggestions?
The overshoot seems to stay the same regardless of frequency setting, until it distorts like in the 1MHz image, which starts around 500KHz, where the period becomes the same width as the overshoot ripple.
(The 1MHz square wave shape is showing just a portion of the overshoot ripple, hence the distorted shape for example).

The triangle and ramp are perfect and boring, so I won't bother with pics.
« Last Edit: May 28, 2019, 01:19:09 am by TERRA Operative »
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #38 on: May 31, 2019, 02:12:24 am »
Moar updates.

It turns out that the Original HP Option 002 board I have wasn't working, but I traced it down to a faulty transistor Q8, it seemed to test ok in my ebay component tester, but it was nonfunctional enough to bring the whole thing to a grinding halt. Replacing it got the board working perfectly.

So, seeing as it works fine with no overshoot, and I need to order another revision of PCB anyway, I ended up just copying the PCB layout with a few tiny tweaks here and there (stuff like neatening up things, 45degree corners, etc).
The added benefit of no longer using a 4 layer board is that PCB's will be cheaper. :)
I am thinking that the large ground and supply planes were adding capacitance and causing ringing, maybe. Thoughts?
I could play with pulling the ground planes back a bit, but I figured 'why bother' when I am holding a working design to copy in my hand....

Anyway, the linked images are the new PCB design, and the output from the repaired original Option 002 board.


Once I get this set of PCB's back and the thing tested, I'll be able to start getting some kits made up for those who are interested.
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #39 on: June 29, 2019, 12:31:54 pm »
New PCB's arrived!

I ended up with two batches, first one they ignored the keepout on the top solder mask, so I have a set of 10 boards with and without top solder mask.
Since the original HP part has no top solder mask, I wanted the same to make it look the same.

Original on the top (already had the electrolytics replaced) and new on the bottom. The traces are a 90% match to the original, and all modern parts are used and substituted and the passives have better specs than the original.

Next step, start testing this to make sure my component values and substitutions all work.
« Last Edit: June 29, 2019, 12:34:06 pm by TERRA Operative »
Any circuit design must contain at least one part which is obsolete, two parts which are unobtainable, and three parts which are still under development.

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Offline VK5RC

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #40 on: June 29, 2019, 01:10:15 pm »
That is looking lovely, when you are happy, I will put my hand up for one.
Rob
VK5RC
Whoah! Watch where that landed we might need it later.
 

Offline hnjmkl

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #41 on: May 16, 2020, 06:03:47 am »
I'm late but I would also be interested in a PCB only board or whole kit, thanks
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #42 on: May 16, 2020, 06:58:43 am »
No worries, I'm sorting out the kits etc at the moment for a big run.

It will be delayed for a while, as Japan Post has basically shut down international shipping due to the corona virus, but as soon as restrictions are lifted, I'll get things organised.
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Offline hnjmkl

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #43 on: May 17, 2020, 08:36:34 am »
With reference to the dual input NPN (1854-0475), resulting obsolete, expensive, nowhere to be found, I would propose to focus on AS194, improved device of the AS394, components produced by a company from Riga in Latvia, they seem to be devices seriously built with vision of datasheets. Regards, Franco
 

Offline VK5RC

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #44 on: May 17, 2020, 09:08:51 am »
I am still interested, but no rush.
Thanks, Rob
Whoah! Watch where that landed we might need it later.
 

Offline Tazz

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #45 on: May 17, 2020, 10:00:02 am »
Quoting some 2015 post on group.io:
Quote
pianovt
7/21/15   #70601 

It looks like Bob saved the day! Just in case someone finds this thread in the future while searching for a replacement, here is what I found for the 1854-0475 dual NPN:

Vceo >40V
NF < 3dB
Ft > 15 MHz
Cob < 3pF
hfe > 200 at 100uA
hfe match better than 0.8
Vbe match better than 10mV at 100uA Ic and 5V Vce
Pd 750mW max. at Ta

Vladan


Cob is way to high on LM194 based clone in general. It is not specified on the AS version.
They are generally slow too, as the Hp one so with high Vce/Ic polarisation and high Pd : The Hp one even rated at 750mW is mounted with a dissipator.

 

Offline Tazz

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #46 on: May 17, 2020, 12:34:10 pm »
2N2920AHR seems to be a good replacement. Active product but difficult to find (ST space qualified portfolio).
Microsemi 2N2920(L) is only 350mw max an very expensive.

2915A/2920A from Solid Sate Inc/Texas Instruments, 2N2920 from Thoshiba 2920A from central semi should be good but hard to find or obsolete.

Why not simply MAT01 ? Available anywhere at not foolish price. Ok perhaps a little but expensive for the HV option, but as a general 1854-0475 replacement ?
2920A From Solid State cost only 2$ less than a MAT01GHZ (~17 vs ~19)
« Last Edit: May 17, 2020, 12:57:11 pm by Tazz »
 

Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #47 on: May 18, 2020, 03:53:55 am »
2N2920AHR seems to be a good replacement. Active product but difficult to find (ST space qualified portfolio).
Microsemi 2N2920(L) is only 350mw max an very expensive.

2915A/2920A from Solid Sate Inc/Texas Instruments, 2N2920 from Thoshiba 2920A from central semi should be good but hard to find or obsolete.

Why not simply MAT01 ? Available anywhere at not foolish price. Ok perhaps a little but expensive for the HV option, but as a general 1854-0475 replacement ?
2920A From Solid State cost only 2$ less than a MAT01GHZ (~17 vs ~19)

The circuit will work quite well with two ordinary MPS8099 transistors glued together.

When I built mine it worked fine, without selecting or matching the transistors.

In simulation a miss-match of HFE one transistor 250 and the other 300 results in about 20mV of offset on the output.

I would try ordinary transistors before going chasing after special parts.

Total Power dissipation for both transistors is around 180mW.

The HV Option 002 amplifier schematic is similar to the normal output. Look at the schematics in the service manual. I am guessing the dual transistor was copied from there.  :-//

Regards,
Jay_Diddy_B

« Last Edit: May 18, 2020, 03:55:53 am by Jay_Diddy_B »
 
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Offline Tazz

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #48 on: May 18, 2020, 06:09:48 am »
Yes going back in the thread show me that I should have reread all first instead of going through all reference catalogs ...  :-DD
« Last Edit: May 18, 2020, 09:19:14 am by Tazz »
 

Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #49 on: May 18, 2020, 01:28:20 pm »
Tazz,

You can buy a *lot* of general purpose transistors for the price of the MAT01 or equivalent. You may even have some  ;D

The transistor in the input stage have 45V VCE. (+/- 30V minus the  15V Zener)

So you need 60V parts.

I used 80V parts.

Jay_Diddy_B
 


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