Signal generator recommendation please - Page 1
Forum section: electronics / testgear

author: peter-h
author_rank: Super Contributor
timestamp: March 22, 2021, 04:51:44 pm
content: I have an old HP 3314A from the 1980s and it needs regular repair. It has a load of reed relays and the switches need replacing. I have the service manual for it but... It cost about 5k-10k way back then.Now the market is full of them; all of them seem to be Chinese and some look like they are junk. I tend to think that when the on-screen text is not even lined up properly the rest of it must be junk.I don't want to pay more than say $300 or so. I can get the old HP 4-digit priced ones on Ebay for that much. Don't need arbitrary waveforms. Do need a reasonable amount of output, say 10V. Don't need more than 10MHz; have a Marconi 2024 to go high up.Which make is of reasonable quality?Thank you in advance.

author: nctnico
author_rank: Super Contributor
timestamp: March 22, 2021, 05:49:02 pm
content: Yeah... I have replaced all the reed relays in the 3314A I used to own a decade ago. What are your requirements in terms of THD? If you just need some signals to tests with then I think one of the newer Feeltech units (FY6900 for example) is good enough. If I where to replace a HP 3314A that one would be at the top of my list. Much more convenient compared to some old boat anchor from HP. If the Feeltech unit breaks you just buy another one and still come out on top.

author: peter-h
author_rank: Super Contributor
timestamp: March 22, 2021, 06:19:45 pm
content: No special THD requirements.FWIW I thought the Banggood stuff did look extra cheap... But I guess they do work well. I would probably go 2x up the price range from that.

author: tautech
author_rank: Super Contributor
timestamp: March 22, 2021, 07:15:50 pm
content: Have a look at SDG1032X....top end of your budget I know however I've had a good run with dozens I've sold.

author: nctnico
author_rank: Super Contributor
timestamp: March 22, 2021, 07:28:03 pm
content: Quote from: peter-h on March 22, 2021, 06:19:45 pmYup and you won't gain much in terms of features.

author: graybeard
author_rank: Frequent Contributor
timestamp: March 22, 2021, 10:13:26 pm
content: I am very happy with my Siglent function generator. However this UNI-T UTG932E is well within your budget and may meet your needs.

author: peter-h
author_rank: Super Contributor
timestamp: March 23, 2021, 07:06:12 am
content: The Siglent SDG1032X looks fine actually.Is there anything in the HP3314A which makes it worth repairing? Does it have low THD or something like that?The engineering inside is amazing

author: graybeard
author_rank: Frequent Contributor
timestamp: March 23, 2021, 07:34:10 am
content: Quote from: peter-h on March 23, 2021, 07:06:12 amIf you have a Bode Plot capable Siglent scope the SDG1032X should work with it.

author: tautech
author_rank: Super Contributor
timestamp: March 23, 2021, 07:48:45 am
content: Quote from: graybeard on March 23, 2021, 07:34:10 am^^^

author: nctnico
author_rank: Super Contributor
timestamp: March 23, 2021, 09:04:48 am
content: Quote from: graybeard on March 22, 2021, 10:13:26 pmThat looks nice. And it seems to be fanless as well.

author: peter-h
author_rank: Super Contributor
timestamp: March 23, 2021, 09:35:29 am
content: I normally open up anything with a fan and either replace the fan with a silent one or (if it is say a 5V DC one) put a couple of diodes in series with itMost equipment designers throw in fans without any thought for how much airflow is actually needed, and in most cases where forced cooling is needed the airflow actually needed to remove the pool of warm air is tiny.

author: Martin72
author_rank: Super Contributor
timestamp: March 23, 2021, 10:47:11 am
content: I like my SDG-1062X, but:Quote30Mhz, 2-channel, 14bit, 200MSa/s....Not the worsest one.

author: Hexley
author_rank: Regular Contributor
timestamp: March 23, 2021, 08:18:11 pm
content: Quote from: peter-h on March 23, 2021, 07:06:12 amOne unusual capability of the HP3314 is its ability to phase-lock to an input signal and either multiply or divide the frequency by N. The phase of the output may be adjusted with respect to the input up to +/- 180 degrees or so.Handy for some timing needs, even if not something one uses every day.I also like the design of the output attenuator, in which a single button click can change the output by an order of magnitude. Surprisingly handy when checking the dynamic range of circuits like amplifiers or filters.

author: Doddy883
author_rank: Contributor
timestamp: March 23, 2021, 09:42:53 pm
content: +1 for the Uni-T UTG932/962. Very pleased with mine. It's compact and performs well - I watched a Youtube video comparing the THD to other (more expensive) generators and it was decent, beating some of them. Unfortunately I can't find the video now!There is a thread going on here though,https://www.eevblog.com/forum/testgear/uni-t-utg932utg962-200msas-function-arbitrary-waveform-generator-220394/

author: peter-h
author_rank: Super Contributor
timestamp: March 28, 2021, 04:40:01 pm
content: I repaired the HP3314 yet again, using up my stock of reed switches, so the main thing I would get with one of the chinese boxes would be the nice scope-like display. And they are much more portable.How can these reed switches fail, when they are supposed to do, what, 100M operations?

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: March 28, 2021, 07:11:03 pm
content: The fans inside these units are like the warning on your mustard jar telling you to keep it refrigerated. Useless.

author: SilverSolder
author_rank: Super Contributor
timestamp: March 28, 2021, 09:01:21 pm
content: Quote from: peter-h on March 28, 2021, 04:40:01 pmIf they are what I think they are, they are not really reed switches... they are leaf-spring key switches, known within HP as the “Bill West switch” after its inventor.They don't age gracefully in all examples. I have some that work smoothly, and some that are in need of help...You can fix the ones you have, usually without buying parts. Search for 'Bill West Switch" even here on this forum, lots of advice...

author: nctnico
author_rank: Super Contributor
timestamp: March 28, 2021, 09:24:26 pm
content: Quote from: SilverSolder on March 28, 2021, 09:01:21 pmNo. There is a whole bunch of reed switches inside the HP3314A. I had one too and in mine the reed switches stopped working after the unit had been running for a while. I never quite understood the failure mode. Maybe the contacts got magnetised over time and became sticky.I owned a later model 3314A with rubber keys. The leaf-spring switches are awfull to use and in general I avoid HP equipment which has those. I hope Bill West didn't invent anything else to cause inconvenience to humankind.

author: peter-h
author_rank: Super Contributor
timestamp: April 02, 2021, 08:20:31 am
content: I've just done ALL the reed switches I can find in the HP3314A. About 10 of them. Now it works find without any error codes. Yes I agree it must be magnetisation, because reed switches have an incredibly long life.They were spot-welded, not soldered, so one has to cut them out and solder in the replacements.I will get the SDG1032X - thanks for the tips. It looks like a nice unit.