Types of input connectors for Spectrum Analyzers - Page 1
Forum section: electronics / beginners

author: tiofilo75
author_rank: Contributor
timestamp: October 11, 2013, 04:35:43 am
content: I recently had the chance to play with one of the spectrum analyzers from my school and noticed that the signal input was a regular BNC connector like you would find on an oscilloscope. I have seen other spectrum analyzers on YouTube like the Rigol 815 and noticed that there connections are different. I was just curios as to what type of connector that was and whether a regular BNC cable would work on. Thanks.

author: marshallh
author_rank: Unknown
timestamp: October 11, 2013, 04:49:27 am
content: Spectrum analyzers past 1ghz will typically have type N connectors which are good up to 11ghz. I use a BNC converter on mine after an attenuator to keep from blowing up the input (30dB type N)

author: Lukas
author_rank: Frequent Contributor
timestamp: October 11, 2013, 06:40:29 am
content: I'm wondering why spectrum analyzers all have N connectors whereas other equipment operating in the same frequency range (really fast 'scopes, VNAs) have SMA-like 3.5mm ... 1mm connectors. Any ideas?

author: senso
author_rank: Frequent Contributor
timestamp: October 11, 2013, 07:06:48 am
content: Mechanically stronger?

author: ve7xen
author_rank: Super Contributor
timestamp: October 11, 2013, 07:09:59 am
content: Quote from: Lukas on October 11, 2013, 06:40:29 am"Really fast" needs something better than Type N.Shahriar of The Signal Path did a great video on RF connectors and some basic RF building blocks.

author: Dago
author_rank: Frequent Contributor
timestamp: October 11, 2013, 07:11:05 am
content: Quote from: marshallh on October 11, 2013, 04:49:27 amN-connectors are often used higher than that. I have a HP 8592A spectrum analyzer that goes up to 22 GHz and it has an N-connector. Not sure if they use a different connector if it would have the option that would extend the range to 26.5 GHz.Quote from: Lukas on October 11, 2013, 06:40:29 amDon't quote me on this but my guess is it might be due to the fact that they use less space and can handle less power. Scopes usually have 2-4 channels and those SMA-"type" connectors are a ton smaller than N-connectors. Also spectrum analyzers are often rated for over a watt of input power which MIGHT have something to do with it (not sure).

author: sub
author_rank: Regular Contributor
timestamp: October 11, 2013, 10:32:09 am
content: Quote from: Dago on October 11, 2013, 07:11:05 amN is more mechanically stable and doesn't require a torque wrench. SMA is so small that the slightest force on the end of an adaptor will correspond to a huge torque on the connector.

author: KJDS
author_rank: Super Contributor
timestamp: October 11, 2013, 11:00:20 am
content: Precision N-type connectors are good to 18GHz as standard and some are spec'd to 20 or 22GHz. Standard N-types are spec'd to 12.4GHz. They are mechanically robust, an SMA on the end of a heavy Rf cable could easily be bent. Most VNA's either use APC7 or N-type.BNC are ok to about 1GHz, TNC, the threaded version works to a little higher than that.

author: sub
author_rank: Regular Contributor
timestamp: October 12, 2013, 12:32:04 am
content: This page has been quite useful to me in the past:http://www.microwaves101.com/encyclopedia/connectors.cfm

author: olsenn
author_rank: Frequent Contributor
timestamp: October 12, 2013, 12:53:00 am
content: If I was sourcing a spectrum analyzer for a school, I would definitely get the cheapest model on the market and I would enure the input is AC coupled and highly attenuated so that a student accidentally applying a 12Vpk sine wave doesn't blow the input. Are there any hi-z DSA's out there?

author: sub
author_rank: Regular Contributor
timestamp: October 12, 2013, 01:46:38 am
content: Quote from: olsenn on October 12, 2013, 12:53:00 amI've used an HP3585A before, which you can set to high-Z and which goes to 40MHz. I've not seen anything targeted at RF, though, with anything but 50-ohm; not that I've been looking.Mini-circuits make some connectorised limiters for $50 each that you could put on the front panel if the frequency was right.

author: PA4TIM
author_rank: Super Contributor
timestamp: October 12, 2013, 07:57:49 am
content: My SA's all have N connectors, I had a Tek CAI SA (digital up to 1 GHz) that had a F connector. I do not use N. There are two types of N, not all N go up to many GHz. Forgot the difference but if I remember wellJ. Dunsmore describes the difference in his book about microwave measurements ( using a VNA).I have a N to GR-874 adapter on my SA's (Tek 2710 and 2712) I have a lot of GR stuf like attenuators, airlines, adjustable stubs, trombones, adapters, mixer, T's, L,s, DC blocker etc. I love those unisex connectors, they performe very good, if I stack a bunch of those things together anf use my Tek 1S2 TDR I can hardly see the connections. They are not easy to find over here. But I am lucky to have some friends that visit a lot of ham fests etc and they search for me. Hope to find a slotted line and accessoires or the dielectric testset one day.A part of my collection:With bnc you see the impedance jumps. But I never use N so I can not tell how that looks with TDR.I want GR-874 chassismounts on one of my my vna's too, instead of the SMA (not made for repeating connections), I now use SMA to SMA adapters on it so I can replace those). My other CVNA's have bnc (one goes to 110 MHz, the other 1300 MHz) Good bnc's go up to 2 or sometimes 3 GHz but it is not a very constant connection. Many Chinese BNC's are only good upto a few hundred MHz or less. Also old (NOS) ex ethernet bnc parts are useless for RF