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| Cloning the HP3325A Option 002 - HV Output |
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| TERRA Operative:
Some more shots. |
| TERRA Operative:
And a few more, showing the shield. Someone might find these pics useful. :) |
| TERRA Operative:
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. |
| TERRA Operative:
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 |
| Neomys Sapiens:
--- Quote from: TERRA Operative on May 16, 2019, 02:12:55 am ---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? --- End quote --- 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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