Frequency counter advice - Page 1
Forum section: electronics / testgear

author: EvgenyG
author_rank: Regular Contributor
timestamp: February 18, 2025, 01:27:05 am
content: Hi All,I'm looking to buy a second-hand frequency counter and narrowed down my choices to HP/Agilent 53131A with a 3Ghz prescaler or Aim TTi TF930. I only need to perform accurate frequency measurements and not interested in other features like totaliser/other time measurements. I've recently learned that most bench top spectrum analyzer units come with a pretty good frequency counter built in, so that could be another option. Coincidentally, I've just acquired a Tek 2711 but haven't taken it apart to "improve" its options to enable frequency counter yet. I was wondering how frequency counting accuracy compares on dedicated units vs spectrum analysers. I do have a GPSDO unit to check/calibrate against.Currently I use an older EZ signal generator that has a 2.7Ghz frequency counter built in, but its accuracy is not great. It is also a pretty basic signal generator, so I was looking to upgrade that, but all new signal generator units in my price range have a frequency counter that goes only to 200-300Mhz.What are this forum thoughts on this?

author: Smokey
author_rank: Super Contributor
timestamp: February 18, 2025, 01:32:58 am
content: Quote from: EvgenyG on February 18, 2025, 01:27:05 amyou should define what that means. What do you consider accurate? what are you trying to do?

author: EvgenyG
author_rank: Regular Contributor
timestamp: February 18, 2025, 01:34:29 am
content: Quote from: Smokey on February 18, 2025, 01:32:58 am1ppm or better. Radios RX/TX alignment.

author: pdenisowski
author_rank: Super Contributor
timestamp: February 18, 2025, 10:24:42 am
content: Quote from: EvgenyG on February 18, 2025, 01:27:05 amA professional spectrum analyzer should specify the frequency counter accuracy, and this depends in part on the accuracy of the frequency reference, either external or internal (which should also be specified).Unless I'm doing totalizer, etc. type measurements or things like Allan deviation, I almost never use my dedicated counter for frequency measurements.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 18, 2025, 11:03:13 am
content: The HP/Agilent units look quite expensive if you really need to go to 3 GHz. I have no experience of the TTi counter either... I have a Racal 1998 that goes to 1.3 GHz and was a pretty much standard bench counter for mobile radio servicing here in the UK back in the day. The only problem I have had with mine was the EPROM pins tarnish and need pulling/re-seating if the display is frozen on power up (common problem with older test equipment that uses EPROMs).I note you have a GPSDO, I use a Leo Bodnar one whenever I use my counter, the old ovens take ages to settle if not powered regularly, using an external standard with occasionally used counters is more or less essential.SJ

author: Fryguy
author_rank: Regular Contributor
timestamp: February 18, 2025, 12:43:17 pm
content: I bought a used Fluke PM6685 a couple of month ago , a really nice unit with OCXO option and 3GHz input extension .This might work for you too and they are not that expensive .https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg5746733/#msg5746733

author: wn1fju
author_rank: Frequent Contributor
timestamp: February 18, 2025, 12:46:02 pm
content: You really can't go wrong with the HP 53131A. Just make sure that whatever counter you buy either has the ovenized oscillator option or you can use your GPSDO as an external timebase.As far as measurements other than frequency, you might not need or want them now, but it is amazing how the ability to do things seems to magically expand to the capabilities of your test equipment.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 18, 2025, 02:58:16 pm
content: I service a lot of radios, not too many in GHz though.I agree with pdenisowski. a spectrum analyzer is the way to go. It will tell you the freq and also show you the unwanted signals at the same time. I use a HP Service Monitor for most radios. Has a pretty good SA;Your SA apparently can be upgraded, as you already know.https://groups.io/g/TekScopes/topic/silk_purse_to_sow_s_ear/7634111