Michael Black wrote on 5/27/2017 7:24 PM:
On Sat, 27 May 2017, Jeff Liebermann wrote:

On Sat, 27 May 2017 12:55:02 -0400, wrote:

Look for something that has a built in prescaler. Something like
this:
http://www.ebay.com/itm/Blue-RF-Signal-Frequency-Counter-Cymometer-Tester-0-1-60MHz-20MHz-2400MHZ/172396798620

The basic counter goes from 100KHz to 60MHz. The other ranges use a
prescaler to divide down the input frequency so that it ends up at
less than 60MHz and can be counted.

I"m assuming those really cheap portable counters are using prescalers,
since they only start counting at 50MHz or something. INtended for two way
radio checking I assume, so you don't need the lower frequencies, and a whip
or rubber duckie antenna will pick up the output power fine.

I've certainly thought about buying one of those cheap ones, hoping I could
bypass the prescaler, though I suspect another issue, the prescaler isn't a
decade counter. Back when Heathkit came out with a frequency counter, circa
1971, the prescalers were decade counters, and things got better as they
improved, and the frequency counters had higher limits. But that sort of IC
seems out of fashion now, so the prescalers are meant for other things, and
offer a binary division, so bypassing it in the counter (and maybe adding an
input stage) means the clock for the counter is "wrong".

I don't think the prescaler is the problem is it? The problem is the
inappropriate front end. If you design a decent front end and feed the
prescaler with that signal it should work at lower frequencies ok. It may
not have timing controls to let you measure below some 10s of Hz or so, but
is that really a problem? Or do the prescalers work in some way I'm not
familiar with so they just don't operate at lower frequencies?

--

Rick C