Author Topic: Must-have RF "Plumbing" for the lab (Read 10711 times)

dmills · « **Reply #25 on:** January 20, 2019, 01:58:52 am »

SMA is a reasonable choice, but keep a 'connector saver' on anything you care about, and watch the pin length thing on males if they might ever be plugged into something expensive (Short is safe and will make very little difference below the microwave bands, but a pin that extends too far can distort or damage the mating female).

There is a reason the guys who own the expensive torque wrenches and Gore cables also own connector gauges (Not that you need any of that stuff as a beginner)!

73 Dan.

OwO · « **Reply #26 on:** January 20, 2019, 03:02:23 am »

You can actually get quite far without any expensive cables or test equipment. Maybe a Rigol spectrum analyzer and a cheap USB VNA at most. I have tested the 415-0033-018 SMA cable ($13 on mouser) to have very good phase stability when flexed, and I've used it in measuring insertion loss with repeatability << 0.1dB. You do not need Gore cables to make accurate S parameter measurements.

tkamiya · « **Reply #27 on:** January 20, 2019, 03:06:17 am »

DC Blocks!

I am finding it's best to standardize your connectors as much as you can on early stages. Then have every conceivable adapters you can think of. Surprisingly, Mini-circuits have quality adapters for not that much money. I've narrowed them down to SMA, N, and BNC. SO239 and PL259 are banned from my lab. For everything else, I use adapters. Your choice may depend on frequencies of interest.

I use cheap kind from eBay a lot. But I am careful not mixing them with high quality types. I think of them as disposable adapters. Many of them are useful. Just look carefully and test them first. I don't have a VNA, and with what have, inconsistencies don't show up much.

Also, buy some RF/microwave gear and take it apart. You can get lots of quality connectors and other expensive components. If you can find dead old HP stuff, they are the best.

jjoonathan · « **Reply #28 on:** January 20, 2019, 05:36:29 am »

> watch the pin length thing on males

The boys aren't the only naughty ones on the playground these days. Cheap SMA females will omit the countersink on the fingers, leaving the edges razor sharp and ready to scrape the gold plating off your expensive becu center pins. I don't think I had ever been warned about this, but it sure made an impression the first time I saw the resulting pile of gold flecks and grime under a microscope!

0culus · « **Reply #29 on:** January 20, 2019, 05:46:09 am »

Quote from: OwO on January 20, 2019, 03:02:23 am

You can actually get quite far without any expensive cables or test equipment. Maybe a Rigol spectrum analyzer and a cheap USB VNA at most. I have tested the 415-0033-018 SMA cable ($13 on mouser) to have very good phase stability when flexed, and I've used it in measuring insertion loss with repeatability << 0.1dB. You do not need Gore cables to make accurate S parameter measurements.

Already have the SA part dealt with. I have an HP 8569B and I have a 8568B on the way soon.

I have a shopping cart at minicircuits started thanks to the suggestions above!

TheSteve · « **Reply #30 on:** January 20, 2019, 05:53:20 am »

The minicircuits stuff is OK but for SMA attenuators I'd head to ebay and look for used Midwest Microwave ones instead, they can often be had for a great deals and not only are the connector tolerances way better so is the response. btw, I am not saying mini circuits won't do the job or that they are overpriced for what you get. I recently spent some time testing and measuring my mini circuits attenuators though and they really didn't make the grade, I won't be using them anymore with my other precision equipment/connectors.

edit - I should add that some other classic names that make quality are Narda, Weinschel, Aeroflex, Amphenol

TheUnnamedNewbie · « **Reply #31 on:** January 20, 2019, 01:32:24 pm »

Quote from: TheSteve on January 20, 2019, 05:53:20 am

edit - I should add that some other classic names that make quality are Narda, Weinschel, Aeroflex, Amphenol

I'd add Radial and Huber+Suhner to that list.

coppercone2 · « **Reply #32 on:** January 21, 2019, 05:34:14 pm »

Yea take out a morgage on the house and do minimal sustainence to live with rice and bananas to maintain a rf hobby.

0culus · « **Reply #33 on:** January 24, 2019, 10:29:55 pm »

I think for now I'm going to get some things from minicircuits (big step up from the cheap stuff on amazon, which will be segregated!) and keep my eyes open for high quality used stuff on ebay, such as Midwest Microwave.

tkamiya · « **Reply #34 on:** January 25, 2019, 06:00:46 am »

By the way.... Just because it's new, paid $$$, and name brand does not guarantee good quality. Personally, I had 6 SMA to N connectors from a well known brand name manufacturer. 5 out of 6 of them will not show repeatable result. On the other hand, my cheap eBay kind works just fine.

Moral of story is, we got to test before trusting them. From eBay sources, quality is not guaranteed. They will likely vary drastically from seller to seller, lot to lot, piece by piece. Before using it for the first time, I always visual check. Then be mindful for any inconsistencies that may show up.

TheSteve · « **Reply #35 on:** January 25, 2019, 06:13:12 am »

Quote from: tkamiya on January 25, 2019, 06:00:46 am

By the way.... Just because it's new, paid $$$, and name brand does not guarantee good quality. Personally, I had 6 SMA to N connectors from a well known brand name manufacturer. 5 out of 6 of them will not show repeatable result. On the other hand, my cheap eBay kind works just fine.

Moral of story is, we got to test before trusting them. From eBay sources, quality is not guaranteed. They will likely vary drastically from seller to seller, lot to lot, piece by piece. Before using it for the first time, I always visual check. Then be mindful for any inconsistencies that may show up.

It doesn't guarantee it but more often then not the top brands produce good quality.

btw, HP rebranded some Midwest Microwave attenuators years ago, something else to watch out for good deals on.
It is possible to get good 18 GHz rated attenuators on ebay for less then $10 shipped quite often.
If you never plan to go past 6 GHz the Mini-Circuits stuff is just fine of course.

0culus · « **Reply #36 on:** March 21, 2019, 09:02:23 pm »

I just ordered a pretty nice goodie back from Mini-circuits to get me started. I'm also keeping my eyes peeled for deals on fleabay for Midwest Microwave stuff.

Kalvin · « **Reply #37 on:** March 21, 2019, 11:53:23 pm »

Downconvert early and upconvert late, so you do not need that much expensive stuff as you keep the frequency below 1 GHz or so as long as possible.

jlmoon · « **Reply #38 on:** March 25, 2019, 02:25:55 am »

Don’t forget about Kings silver connectors. Pretty nice parts.

xmo · « **Reply #39 on:** March 25, 2019, 04:01:39 am »

I have also always like Kings parts. Delta and Huber+Suhner are also good quality.

As you accumulate your RF adapters and accessories you will soon have an organization problem. Keeping everything jumbled together in a box or bin will just lead to frustration when you need to find something. Also, having precision RF parts banging around and into each other isn't good for your results.

There are a lot of ways to solve the issue. A plastic storage organizer from a home center is a good start. Back when I needed to take these things into the field I used a lid-locker tackle box. The adapters went into the compartments and the inside was just right for cables and accessories.

Now I go out less frequently so I just take what I need in padded plastic bags.

For organization in the lab I found a cabinet that's called an end mill dispenser. It's meant for tool room use in machine shops. It has two drawers pre-fitted with sturdy dividers. These are just right for adapters, attenuators, terminations and so on.

A third drawer is open and is perfect for RF accessories like splitters, bridges, couplers and RF probes.

Here's what that looks like:

0culus · « **Reply #40 on:** March 25, 2019, 04:13:46 am »

That looks really really nice! Another thing on the want list for the new lab...

TheSteve · « **Reply #41 on:** March 25, 2019, 05:24:15 am »

Very nice!
I am not too concerned about my N/BNC etc but could use a better storage solution for my 3.5/2.92/2.4 and 1.85mm collection.

0culus · « **Reply #42 on:** March 29, 2019, 01:54:12 am »

Got a small box of goodies today from Mini-Circuits. This along with the stuff Steve is sending me will get me a long way towards standardizing my lab around SMA. Very impressed with the quality of the Mini-Circuits hardware. I know there's better stuff, but for the price, it's nice to be able to get new stuff that hasn't been abused yet by some hamfist.

TheSteve · « **Reply #43 on:** March 29, 2019, 02:47:21 am »

Nice, hopefully you get the box of goodies next week.

0culus · « **Reply #44 on:** April 01, 2019, 05:17:17 am »

Who makes the best quality SMB stuff? Mini-circuits doesn't carry SMB at all as far as I can tell, but it would be handy to have a few adapters to switch them to SMA for working inside HP RF gear, since they use SMB a lot for the lower frequency components.

0culus · « **Reply #45 on:** April 02, 2019, 06:01:22 pm »

Got a box of fun goodies from Steve today! Thanks!!!

TheSteve · « **Reply #46 on:** April 02, 2019, 06:16:37 pm »

BTW, while the Mini Circuits stuff doesn't do to well above the rated frequency the Narda stuff generally looks great to 18 GHz no matter the rating on the label.

0culus · « **Reply #47 on:** April 02, 2019, 06:19:34 pm »

Quote from: TheSteve on April 02, 2019, 06:16:37 pm

BTW, while the Mini Circuits stuff doesn't do to well above the rated frequency the Narda stuff generally looks great to 18 GHz no matter the rating on the label.

Good to know, thanks!

I forsee a VNA in my future...

0culus · « **Reply #48 on:** April 02, 2019, 07:50:28 pm »

Quote from: TheSteve on April 02, 2019, 06:16:37 pm

BTW, while the Mini Circuits stuff doesn't do to well above the rated frequency the Narda stuff generally looks great to 18 GHz no matter the rating on the label.

What about those two Fairview pads?

TheSteve · « **Reply #49 on:** April 02, 2019, 11:07:19 pm »

I'd have to check my notes on those ones. It was just the Narda ones that really stood out due to how well they performed.


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Author Topic: Must-have RF "Plumbing" for the lab (Read 10711 times)

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