WTB Knobs for a HP 3582A Spectrum Analyzer - Page 1
Forum section: electronics / general

author: Dacke
author_rank: Regular Contributor
timestamp: July 27, 2019, 11:31:19 pm
content: I'm looking to buy a couple of knobs to replace the broken ones on a 3582A, I do occasionally see them on Ebay but the prices are high. They seem to be used on a few different pieces of HP gear, just wondering if someone might have some kicking around. The part numbers are 0370-1005 for the smaller one and 0370-3009 for the larger one, these are for a 3mm shaft I believe. Picture attached of the knobs in question. Thanks.

author: beanflying
author_rank: Super Contributor
timestamp: July 28, 2019, 01:37:16 am
content: Maybe not 3mm shaft, your 'freedom units' conversion might be a little offThis might be an option for youhttps://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/msg2265270/#msg2265270or this one if you are missing the hardwarehttps://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/msg2267373/#msg2267373There is a bit of variation with this style knob depending on the bit of gear. Some of mine have very long rear tangs (427A multimeter) and one of my 5000 series counters has large (0.25" not 6mm) and small (1/8" not 3mm). I haven't modelled the smaller one as they are intact on mine.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 28, 2019, 04:32:18 am
content: While it wouldn't be "like new" I would be very tempted to repair these knobs. You appear to have all of the important bits. With careful application of adhesive and clamping by wrapping a string around the knob a fully functional and nearly invisible repair should be achievable.

author: Dacke
author_rank: Regular Contributor
timestamp: July 28, 2019, 03:18:44 pm
content: Thanks beanflying, I don't have a 3D printer unfortunately, unless you are willing print a couple of them and I would pay for it of course.Catalina, Yes for now I just used a tiny amount of glue to hold these together and left them in a small pair of vise grips for a few hours, I think they will be ok for a while, they seem to be holding up. The smaller one is questionable, it's cracked in various places.Edit: A picture of the instrument in question attached, it does function fine now (I had to do a couple repairs inside) but needs a lot of cosmetic work. They guy I got it from basically gave it away. The large adjustment knob I've already been able to find for pretty cheap and is on it's way. Both of the aluminum panels for the top and bottom I had to beat back into shape with a rubber mallet and after about an hour of work, they finally fit nicely.

author: beanflying
author_rank: Super Contributor
timestamp: July 28, 2019, 05:22:24 pm
content: You can get them printed by a commercial service locally and you might want to double check the OD of the brass internals to make sure my designs will take them before proceeding.As I am halfway around the world try local first or even drop your State here someone more local might be able to help.

author: Dacke
author_rank: Regular Contributor
timestamp: July 28, 2019, 07:04:57 pm
content: Just now noticed where you were from, yeah that would be a little pricey to ship as I'm in South Florida. There do seem to be commercial services within a few miles from me though, I can ask them tomorrow.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 28, 2019, 08:01:51 pm
content: A bigger problem than the broken knobs is the missing knobs and the broken shafts they used to sit on. You can buy or print replacement knobs, but the shafts will also have to be replaced. I have had some luck fabricating replacements. The problem is finding appropriate fiberglass or possibly carbon fiber blanks to start with. Most available stock is optimized for bending stiffness, not the torsional stiffness required here. I don't know how important insulation is in this particular application for either safety or signal integrity reasons. If you can convince yourself there is no issue you can use metal rod, much easier to obtain and put the necessary flats on.

author: Dacke
author_rank: Regular Contributor
timestamp: July 28, 2019, 09:43:39 pm
content: No problem with any of the shafts that I know of, all of them seem to be brass and all controls are responsive. I had to disassemble and remove the entire front face of the unit when I first got it, as some of the buttons were stuck and a wire to one of the front input terminals had broken off. I fixed these issues and while I was in there I checked and cleaned everything. You might be referring to the areas where it looks like there were knobs that possibly broke off, but those are actually just fine screw adjustments for astigmatism and balance (DC offset compensation on the inputs). There are no knobs for these as they generally don't get changed much once they are set correctly.

author: precaud
author_rank: Frequent Contributor
timestamp: August 03, 2019, 01:24:47 am
content: What controls on the 3582A are these from? I'll look and see what I have. Or PM me with the info.

author: Dacke
author_rank: Regular Contributor
timestamp: August 10, 2019, 05:38:15 am
content: Apologies precaud, I've been away for a bit and didn't check this thread. I've replaced all the knobs that were damaged or missing except for the trigger level knob, which is missing its cap and has a long crack down two sides. In the image I posted above of the 3582A, it's the knob next to the large sensitivity knobs. I'm still checking around for that one.

author: Kryten 2X4B
author_rank: Contributor
timestamp: May 07, 2020, 11:23:44 am
content: Hi,I missed this post originally, but if you are still looking for some knobs for your 3582A I have some. A few years ago I bought a 3582A front panel on ebay to make some repairs to my 3582A. Recently I've also used some of the parts to repair one of my two HP 3580A spectrum analyzers. From the picture I may have three knobs you need. Let me know if you are still looking for these parts. I'm also looking for an unlabeled cap and the metal ring for a knob the size of the CAL knobs on the 3582A.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: June 06, 2020, 03:29:12 am
content: Quote from: CatalinaWOW on July 28, 2019, 04:32:18 amI concur. I repaired 3 of the knobs on my HP3580A with a bit of 5-minute epoxy applied with a toothpick and a small clamp to hold the crack shut. They were broken in just the same way as yours. It worked out well and I can hardly see the repair.