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Adding front panel output to 8340B
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Reg,
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I¡¯ve done it before. It¡¯s a task but not terribly difficult. The biggest problem is finding the bracket required to mount the connector to the front panel frame, the HP part number is 08340-20076. It¡¯s got some odd offsets machined into it so it will fit where it has to fit. There¡¯s a guy in France that has one or two listed on eBay for $120 plus $53 shipping. I think the listing says ¡°or offer¡± but I haven¡¯t contacted him. I was tempted to try to machine one with the help of a friend but that never happened. I managed to snag one with a connector on eBay for $50. Another guy doing the same change came up with an alternate method of mounting the connector but I don¡¯t know how mechanically stable it is compared to the original bracket. You will need to modify the firmware to account for the smaller loss in the semirigid coax as the run to the rear panel is obviously longer. Will you also be adding the 08340-60175 attenuator? If so that¡¯s another firmware change. The firmware changes are done from the front panel so it¡¯s not a big deal. Hopefully your unit still has the cal constant/firmware paper listing in a bracket at the left rear inside the top of the unit. I¡¯m getting ready to do an attenuator/rear to front output update on a unit arriving tomorrow or Friday. Let me know if you have any questions. I have a hand-drawn sketch of the bracket, with dimensions my friend made but as I said, I found one so I never made the bracket and couldn¡¯t guarantee the drawing and dimensions are 100% correct. Steve Krull WB0DBS On Nov 21, 2023, at 3:06?PM, Reginald Beardsley via groups.io<pulaskite@...> wrote: |
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Steve
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Apart from the firmware update, is there much involved in doing a retro -fit of the attenuator to a 'front output' instrument that does not have it? I see the attenuator is out there- at prices that vary - from the sublime to the ridiculous....... DaveB, NZ -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Steve - Home Sent: Wednesday, November 22, 2023 11:40 To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] Adding front panel output to 8340B Reg, I¡¯ve done it before. It¡¯s a task but not terribly difficult. The biggest problem is finding the bracket required to mount the connector to the front panel frame, the HP part number is 08340-20076. It¡¯s got some odd offsets machined into it so it will fit where it has to fit. There¡¯s a guy in France that has one or two listed on eBay for $120 plus $53 shipping. I think the listing says ¡°or offer¡± but I haven¡¯t contacted him. I was tempted to try to machine one with the help of a friend but that never happened. I managed to snag one with a connector on eBay for $50. Another guy doing the same change came up with an alternate method of mounting the connector but I don¡¯t know how mechanically stable it is compared to the original bracket. You will need to modify the firmware to account for the smaller loss in the semirigid coax as the run to the rear panel is obviously longer. Will you also be adding the 08340-60175 attenuator? If so that¡¯s another firmware change. The firmware changes are done from the front panel so it¡¯s not a big deal. Hopefully your unit still has the cal constant/firmware paper listing in a bracket at the left rear inside the top of the unit. I¡¯m getting ready to do an attenuator/rear to front output update on a unit arriving tomorrow or Friday. Let me know if you have any questions. I have a hand-drawn sketch of the bracket, with dimensions my friend made but as I said, I found one so I never made the bracket and couldn¡¯t guarantee the drawing and dimensions are 100% correct. Steve Krull WB0DBS On Nov 21, 2023, at 3:06?PM, Reginald Beardsley via groups.io<pulaskite@...> wrote: |
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Steve,
Please send me the drawing. I've got machine tools. A list of relevant parts numbers would be a huge help. The manual I have is a 500+ scan of multiple manuals and it's very difficult to find the correct section. I settled on using a 1 TB iPad Pro as a documentation repository. The size is handy, but the UI is awful. The cal sheet is there. At this point I don't know what I have. Yesterday was just a quick function test before the return period expired. As is common, it didn't work on arrival, but was fine after I seseated connectors I could access. All I've done is enough work to verify the 8340B worked. As soon as the basic lighting and wiring is done I'm building a 12'x16' screen room using 28 gauge galvanized steel with soldered seams and full TEMPEST treatment, building a 2nd 6 bay rack and cabling it up so I can use it. I've got workmen coming next week to wire and light my shop. I finally conceded I'm too old and out of shape to do anything but minor changes myself. Worse yet, I haven't bent conduit in over 40 tears and that's as real art. Because of space limitations both the bench and the racks are going to be on rails. The racks for rear access and the bench to bring the bench to the correct instruments with all graphic displays at eye level. Bench at 90 degrees between the racks. Lots of metalwork to do. Thanks, Reg |
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Dave,
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Apart from the firmware and semirigid coax needed, the installation is straightforward. If you want the best accuracy there is a detailed attenuator calibration procedure to follow. It¡¯s a bit laborious and of course, requires more (and calibrated!) test equipment. If you shop for an attenuator try to get one with the mounting plate and ribbon cable attached. They do go for silly money but occasionally a reasonably priced (for me, anyway) one shows up. If I remember correctly I paid about $100 shipped for my last one, with the mounting plate and cable and a 30 day return privilege. Steve On Nov 22, 2023, at 3:13?AM, Dave Brown <2c39a@...> wrote: |
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Reg,
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Send me a PM, my replies to you are bouncing. Steve On Nov 22, 2023, at 7:31?AM, Reginald Beardsley via groups.io <pulaskite@...> wrote: |
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How are you going to switch the software to match each line? On Thu, Nov 23, 2023 at 8:32?AM Reginald Beardsley via <pulaskite=[email protected]> wrote: Bruce, |
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Physical space might become a problem (depending where you put the attenuator.? HP has a service note covering rear to front "upgrade" that describes changes to a resistor on the ADC board.? You could implement a relay to switch a resistor in parallel with the existing resistor and retain the calibration. (The rear output has more attenuation due to coax length)
I did not do that because I only use the rear output with my 8510 which does not care about the small change in output. Cheers! Bruce |
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