Spectrum Analyzer for up to 26.5GHz, HP8593E and accessories - Page 1
Forum section: electronics / testgear

author: tkamiya
author_rank: Super Contributor
timestamp: November 02, 2018, 04:05:20 pm
content: I recently acquired SpecAn for 26.5GHz, HP8593E with N fitting for input port.What I didn't realize was, everything will become so hard to obtain; even silly things. Even high quality DC cutoff, cable harness, connector adapters, etc, etc, etc, will end at 18GHz. Moving to SMA isn't that much better. 3.5mm is super high cost, fragile, and again, not as available.I have lower grade stuff connected because I don't need that kind of frequency response very often. But when I do, I'm having have to consider if decline in level, non linearity in trace, etc, is due to connection or DUT.I have a very good surplus source locally, so once a week, I'm there looking for this stuff. Occasionally, I find them. Only thing new I see that goes beyond 18GHz is usually VNA related ultra stable cable for thousands. I cannot afford that.What do you do???

author: TheSteve
author_rank: Unknown
timestamp: November 02, 2018, 04:14:40 pm
content: Ebay, patience and very careful selection. As you mention at the higher frequencies everything is delicate so buying used can mean getting worn out crap.I guess it also depends on how precise you need the amplitude to be. At 20 + GHz the loss in everything adds up quickly so be prepared for that. At some point I'll test some high quality SMA adapters to see how they compare to proper 3.5 MM ones above 18 GHz.Oh, don't forget the torque wrenches

author: tkamiya
author_rank: Super Contributor
timestamp: November 02, 2018, 04:26:59 pm
content: I typically only buy new old stock or like new items only.It's amazing. On my SpecAn, I had N to SMA adapter, and a DC block and 3 feet of cable. It was already sucking down 10db. I will have to measure couple of my better cables and write them down, so I can account for them. Even more tricky is bumps on trace. I had a trackGen connected and on full scan, (0.01 to 20GHz) there are quite many bumps. Some appear to be periodic so I'm guessing there is something causing a cavity effect.It's a whole new world!PS. Yes, I have few torque wrenches. That's the first thing I bought.

author: 0culus
author_rank: Super Contributor
timestamp: November 02, 2018, 04:38:55 pm
content: A DC block is something I'm needing as well; any particular recommendations? I managed to find a NOS (still sealed in box) Agilent SMA 10 dB attentuator recently, but like many things, it tops out at 18 GHz.

author: tkamiya
author_rank: Super Contributor
timestamp: November 02, 2018, 04:48:22 pm
content: I bought mine from Mini-Circuits. It is spec'd to 18GHz.Surprisingly, MCL stuff is very reasonably priced and it's a well known company. It's an SMA type though. I'm using it with a reducing adapter.For N type, it ends at 6GHz.It looks like anything better than that, I have to get them from HP/Agilent/Keithly or some other equally high-end companies. Of course, they are well beyond my budget.I'll be right back... I'm going to a store to buy MegaBucks lottery tickets....

author: ogden
author_rank: Super Contributor
timestamp: November 02, 2018, 05:07:22 pm
content: Quote from: tkamiya on November 02, 2018, 04:48:22 pmWhen you buy Ferrari, you should not complain that tires and fuel are so bloody expensive

author: DaJMasta
author_rank: Super Contributor
timestamp: November 02, 2018, 05:23:18 pm
content: There's a reason why SMA stuff typically stops at 18GHz.... cause that's basically what it was designed for. As with other connectors, there are special proprietary variants that go above and beyond (like 3GHz BNC ports on scopes), but 3.5mm connectors are the way to go higher in that form factor. I'll bet the N type connector on the front is a fancy HP-specified variety because typical N type interfaces aren't even necessarily good up to the top end of SMA connector frequencies.Part of the expense is the machining and tight tolerances, part is the engineering, and especially on the used market, a huge part is the rarity. Higher frequency connectors and cables are often much more sensitive to wear and tear reflecting in their performance, so while the initial quantity made is small, the quantity that survive their 20-30 year lifetime and make their way onto the used market in good condition is that much smaller.I'd aim for stuff specified to 18G or so, then just deal with the losses above. Do you really have calibrated sources to 26.5GHz that require very low loss interconnects for absolute measurements? Even at half that bandwidth I find the potential applications dwindling and appropriate measurement cables, connectors, and standards (like SOLT calibrators) to be quite expensive.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 02, 2018, 08:07:26 pm
content: Quote from: tkamiya on November 02, 2018, 04:05:20 pmoption 1: patiently keep looking for used stuffs at bargain price in ebay and pray to God they will appear sometime.option 2: DIY and be happy about it.option 3: dont go 20GHzthere are lot more cans of worm waiting ahead.Quote from: ogden on November 02, 2018, 05:07:22 pmhe bought used Ferrari at a cost of new Toyota. now he realized his used Ferrari is not compatible with Toyota's tires

author: TheSteve
author_rank: Unknown
timestamp: November 02, 2018, 08:12:09 pm
content: I think of my SA/VNA as more of a Bugatti Veyron. The deals do pop up on ebay if you're patient and spend time looking. If you're sticking with lower frequencies I'd go with N based accessories if possible.Of course in the end we all just end up with N adapters/attenuators etc, and then SMA variations and finally 3.5mm variations of them too.

author: tkamiya
author_rank: Super Contributor
timestamp: November 02, 2018, 08:50:23 pm
content: Just spoke with someone at a lab I use. He also suggested going 3.5mm. So that's what I am considering. He didn't think loss will be too much for a simple N to 3.5mm adapter. Or, connector can be replaced with 3.5mm at the SpecAn. HP actually has both as options.It wouldn't have so much of a money problem if I hadn't just replaced tires on my Mercedes-Benz! (and next service is due soon)