New Spectrum Analyser - What Accessories? - Page 1
Forum section: electronics / testgear

author: apelly
author_rank: Unknown
timestamp: December 29, 2014, 12:48:37 am
content: Well, I failed to find a Thanksgiving bargain on a Rigol DSA815-TG, so I just ordered one from Emona. That's OK. John's a cool guy to deal with.As I mentioned in another thread recently, I have never used one before and this is pretty much a Xmas toy: I have no idea what accessories I'll require.If anyone has suggestions, especially with links, for adapters, leads and so on, I'd be very grateful.

author: RRobot
author_rank: Regular Contributor
timestamp: December 29, 2014, 01:09:37 am
content: You should have some 'N' to BNC connectors, as well as an assortment of 'N' type attenuators and BNC cables. Maybe some SMA to whatever connectors as well.I've bought quite a bit from ebay user 'connekt' and have been satisfied with the price and quality.Something like this:http://www.ebay.com/itm/N-Male-to-N-Female-connector-DC-3GHz-5W-watt-30dB-Coaxial-Power-Attenuator-/220956527131?pt=LH_DefaultDomain_0&hash=item3372090a1bhttp://www.ebay.com/itm/N-male-plug-to-BNC-female-jack-RF-coaxial-adapter-connector-/320847616412?pt=LH_DefaultDomain_0&hash=item4ab402199c

author: Rory
author_rank: Frequent Contributor
timestamp: December 29, 2014, 01:44:12 am
content: Hybrid network, return loss bridge or directional coupler for return loss measurements, very handy for measuring VSWR bandwidth. Cannot stress enough the utility of a fixed attenuator at the input when measuring unknown signals.

author: tautech
author_rank: Super Contributor
timestamp: December 29, 2014, 02:00:20 am
content: Tryhttp://rfcoms.com/Aliexpresshttp://www.aliexpress.com/store/203228You like links don't you?

author: xrunner
author_rank: Super Contributor
timestamp: December 29, 2014, 02:02:33 am
content: Quote from: Rory on December 29, 2014, 01:44:12 am^^^

author: VK5RC
author_rank: Unknown
timestamp: December 29, 2014, 02:08:33 am
content: DC block, saves your front end from whoops!

author: apelly
author_rank: Unknown
timestamp: December 29, 2014, 02:19:23 am
content: Message Re. attenuator received and understood. Thank you. Alan, w2aew, has a video about making attenuators. Looks straight forward enough. I haven't looked at prices for pre-made ones yet though.One early thing I intend to dick about with is my house TV coax. Something is subtly wrong and I'd like to see where the fault is. Should I acquire a 75r<->50r adapter?Quote from: tautech on December 29, 2014, 02:00:20 amI do!I was hoping that would be interpreted as "Please share anything you have bookmarked or remember" and not "Please google this for me"So, thanks for the links Tautech.

author: apelly
author_rank: Unknown
timestamp: December 29, 2014, 02:21:04 am
content: Quote from: VK5RC on December 29, 2014, 02:08:33 amAh, yes!I'm glad I started this thread now. You guys are awesome!

author: radhaz
author_rank: Regular Contributor
timestamp: December 29, 2014, 03:53:14 am
content: I recently grabbed one of these:Signal Hound USB-SA44BI got the attenuator and DC block while I was at it.

author: TSL
author_rank: Regular Contributor
timestamp: December 29, 2014, 05:15:38 am
content: I'll vote for the DC block too!For low power attenuators, buy them - they can be found quite cheaply all over eBay and at least you will know you have a fairly accurate device if you stick to name brands such as HP,Weinchel,Marcom, Suhner etc.I have a few no-name units if I feel something might go pop in testing.High power attenuators can be very expensive, but can be made cheaply by buying the attenuator tab without heat sink thus...http://www.ebay.com/itm/NEW-RF-Florida-83-7006TC-3ghz-30db-ceramic-tab-Attenuator-100w-dc-3ghz-/300973661487and soldering that to a copper block that you bolt to your own heat sink. You can also find bolt-down encapsulated types that save the soldering step just leaving you with the connectors and heat sink to sort out.Directional couplers can also be used a samplers, very useful items to have. I bought a 20dB 800-2700Mhz unit from RF shop for $33. They're also good for other things toohttp://rfshop.com.au/directional-couplers-and-splitters/dcs-800mhz-3ghz-low-cost.htmlAs for getting adapters and leads etc..RF Supplier has always been good and is well known in the HAM community.http://www.rfsupplier.com/I buy crimp bulk N's, BNC, SMA etc from them.And... last but not least.. If you've not used an SA before, you might consider reading the "Spectrum Analyzer Basics" app note from Agilent here...http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdfregardsTim

author: apelly
author_rank: Unknown
timestamp: December 29, 2014, 10:52:11 am
content: TSL, thanks for making the effort to reply. That's a lot of good information.I'll update you guys over the next week or two as I get my act together.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: December 29, 2014, 12:00:04 pm
content: A return loss bridge, like the one by VK3DIP, is very cheap and easy to make. Mine works to 1.5 GHz. Don't bother with the VSWR measurement add-on (or hack), it doesn't add anything useful.Another item is a resistive tap, ARRL members can find one on their site... It's part of the W7ZOI power meter. The design is very simple, 3 x 820 Ohm resistors in series, a 51 Ohm to ground. There is a short length of wire to give compensation at higher frequencies. They have 40 dB loss, 100 Watt power rating and are flat to around 500 MHz. All built in a small diecast box.

author: G0HZU
author_rank: Super Contributor
timestamp: December 29, 2014, 02:34:36 pm
content: I don't own an 815 but I thought they already have an internal 50V DC block?I would recommend a decent external limiter if you ever find yourself using it near high power stuff like ham radio. Although you should be using attenuators and/or couplers to protect it from overload damage it is worth including a limiter after the attenuator/coupler as a form of insurance against accidental mistakes in your connections.I make my own limiters (some are fused limiters) but you can buy them ready made. Obviously, a limiter is not a replacement for an attenuator but it does act as a last line of defence if you forget to fit the attenuator or make some other mistake.See below for a few of my homemade limiters. Some include fuses and DC blocks as well. Some are for LF use and some work up to UHF. The UHF one (the short stubby limiter using N connectors) is very low loss with very low VSWR.

author: KD0RC
author_rank: Regular Contributor
timestamp: December 29, 2014, 03:58:18 pm
content: You can even build your own return loss bridge. I built one and it works pretty well for a few dollars worth of parts. If you need more bandwidth (i.e. something that works past 200 or so MHz), you can spend more for a professional one, but for learning, I find this one more than adequate. I also got the benefit from building it myself.https://www.eevblog.com/forum/testgear/homebrew-return-loss-bridge/msg393490/#msg393490Len

author: VK5RC
author_rank: Unknown
timestamp: December 29, 2014, 09:10:34 pm
content: G0HZU I am pretty sure is correct, it must have a built in DC block to tolerate 50V. That s a nice feature.One of the guys in my radio club has one and has been very happy.QST reviewhttp://www.qsl.net/ke4pwe/Test_RIGOL_QST_February%202013.pdf

author: apelly
author_rank: Unknown
timestamp: April 01, 2015, 08:51:16 pm
content: Well guys, just letting you know I finally got off my arse and ordered sufficient stuff to get started. Thanks for your help and advice.Mainly I used ebay guy connekt as recommended by RRobot. After comparing the other sites, connekt seemed to have most of the stuff I wanted at better than average prices. I probably could have dicked around for days on aliexpress, although that's where I picked up a crimp tool from.