Digital step attenuator, PE4302? Anybody? - Page 1
Forum section: electronics / rf-microwave

author: onesixright
author_rank: Frequent Contributor
timestamp: July 13, 2016, 09:22:16 pm
content: Hi there all,Anybody that has some experience with the "PE4302" attenuator? They sell on eBay for round 20 USD.QuoteLike so:eBay auction: #http://www.ebay.com/itm/PE4302-RF-Attenuator-Module-6-Bit-DSA-Digital-Step-0-5-31-5dB-DC-4000MHz-HF-/131666876016?hash=item1ea7f51670:g:hoMAAOSwHQ9WX7fOIm pretty new to the use of a SA, but i do understand i don't wanna blow my front-end... For now I just use a antenna...Any help is welcome / appreciated to not blow it up...

author: KE5FX
author_rank: Super Contributor
timestamp: July 13, 2016, 09:27:02 pm
content: Peregrine makes really cool parts. You can order them from DigiKey or (I believe) directly from Peregrine Semi's website.Your spectrum analyzer should have its own RF attenuator, though, so you shouldn't need to add your own. A DC block might be a better investment.

author: ConKbot
author_rank: Super Contributor
timestamp: July 15, 2016, 01:20:40 am
content: Step 1: know what you're putting into it, to at least set the input attenuation and reference level right. On most the HP spec ans I've used, they want -10dBm at the mixer, so set the internal attenuator to knock your signal down to -10 dBm or whatever your manual says for your SA.2: A minor overload may not be a problem. I've accidentally sent about 18dBm into a SA while it was on the default 6dB attenuation setting (about a 20db overload), none the worse for wear. I'd suspect the first mixer is protected with low capacitance diodes, and could take the full input capability with the attenuator set at minimum, but ill let a real expert comment on that before I go telling anyone it's safe. ( paging w2aew, or anyone else)3: despite front end protection, don't manually set the internal attenuator to 0db (the HPs I've used only go down to 6 via the knob. 0 has to be typed in manually) until your really sure what you're sending in, and only if you really need it. The input protection can only do so much, and an ESD event, or a charged cable overpowering any protection and blowing out your first mixer will make for a bad day, and even that 6db will help.And a related tip for making good measurements, the first mixer sees everything, not just whats in band for what you're looking at. Looking at a signal down low while something off screen overdrives the mixer will make spurs and false signals show up all over the place.

author: rfbroadband
author_rank: Unknown
timestamp: July 31, 2016, 01:34:29 am
content: in terms of protecting your SA: avoid overwriting the min attenuation. Only set it to 0dB if you are absolutely sure you understand your setup!

author: cncjerry
author_rank: Unknown
timestamp: August 02, 2016, 10:34:56 pm
content: Peregrine makes good parts. I used one within my N2PK VNA build for level setting. Here's the issue, though, I don't recommend relying on any digital or stepped attenuator on the front end of an SA for protection. Using one to bring a signal into a specific detection range is one thing; using it for protection is another. It is so easy to make a mistake. Yes, using something like this after a fixed attenuator again, to bring the signal into the right level, is many times necessary but I would put something fixed and reliable in front of it.

author: pherdie
author_rank: Contributor
timestamp: September 01, 2016, 11:45:51 pm
content: I purchased one of those boards and it does work. It's a Chinese copy of the Peregrine evaluation board. I only took a quick look at it so I have no specifics to offer other than I remember the response wasn't all that flat due to significantly greater attenuation (>6 dB?) in the HF region for a given attenuation setting. The attenuation settings can be manually set by a DIP switch which is inside an easily removed shielded enclosure or by reconfiguring for clocked serial communication. If you Google 'P4302' you may be able to find a project using this board and an Arduino to provide communication and attenuation setting readout.I'll concur with others, this is not for use as a protective device on your analyzer. Not withstanding, it does have DC blocking caps on the input and output but I'm sure they're rated at a fairly low voltage.Peregrine has discontinued the PE4302 and replaced it with the PE4312.Quote from: onesixright on July 13, 2016, 09:22:16 pm