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Author Topic: Frequency counter recommendations  (Read 2469 times)

Ike Zimbel

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Re: Frequency counter recommendations
« Reply #10 on: December 03, 2021, 04:20:16 PM »

This is something I'm curious about. I do own a (cheap!) frequency counter, but I don't think I've ever been in a situation where I felt like it was the "right" tool for the job. With almost everything wireless (other than LMRs, I guess) having some kind of a display these days, what do you typically use yours for?

Thanks!

-Russ
A LOT of media folks that show up at the check-in desk are not that up-to-speed on the technical aspects of their RF gear so it's often quicker to just get them to turn it on quickly and use the frequency counter than to get them to hand it over and then start scrolling through menus. That said, if they're that clueless, I'll probably end up tuning it for them anyway if it has to move.
It can sometimes be helpful as an honesty check once someone is on an assigned frequency, too.
And, what Henry said!
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~Ike Zimbel~
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Craig Hauber

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Re: Frequency counter recommendations
« Reply #11 on: December 18, 2021, 07:25:05 PM »

It isn't really a frequency counter (it is also the first time for me that I heard of that type of device), but the tinySA (https://tinysa.org/) could serve the same purpose. It will show you the parameters from the highest signal that is detects. Plus it seems that it can do more then a frequency counter.
This is what I now use.  Just toggle the cursor along the curve and read the number at the peak.  Also useful to see clearly all the harmonics and spurious RF a cheaper transmitter tends to output along with its fundamental. 
For higher resolution than it's tiny (but surprisingly clear) screen, just USB connect to your PC and run its software on that.
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Craig Hauber
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Henry Cohen

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Re: Frequency counter recommendations
« Reply #12 on: December 18, 2021, 09:08:23 PM »

Also useful to see clearly all the harmonics and spurious RF a cheaper transmitter tends to output along with its fundamental.

Just ensure those harmonics and spurious RF on the screen aren't from the SA's input saturating  :-\
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Henry Cohen

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Tim McCulloch

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Re: Frequency counter recommendations
« Reply #13 on: December 23, 2021, 03:52:34 PM »

Just ensure those harmonics and spurious RF on the screen aren't from the SA's input saturating  :-\
So a pad between the SA input and antenna/signal source?  How much attenuation?  /inquiring mind
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Riley Casey

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Re: Frequency counter recommendations
« Reply #14 on: December 23, 2021, 04:08:30 PM »

Thats some serious "show must go on " mojo there Ike.  Not sure I would have sacrificed my PSU for some guitar pedals for the band du jour. Well depends on the band I suppose. :o


... A few years back I was doing RF at a three day festival in Toronto and I found myself crouched on the stage, cutting 4" of the end off the 9v adapter so I could twist the leads together and reverse the polarity to power up some guitar pedals, seconds before the band started...

Henry Cohen

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Re: Frequency counter recommendations
« Reply #15 on: December 23, 2021, 05:29:13 PM »

So a pad between the SA input and antenna/signal source?  How much attenuation?  /inquiring mind

In an ideal world the SA manufacturer will specify the "maximum [usable] input", but you should confirm it isn't 'maximum input, no damage", which means the front end could still be saturating, it's just that no damage will occur. All the credible manufacturers (Keysight, Anritsu, Rigol, R&S, Sigent, Signal Hound, TTI, etc.) specify max input as that which is usable, but it's generally for a CW or narrow band digital signal, not wide band digital such as digital wireless mics/IEM's. For digital mics, add 10dB to the rated RF output to be safe when determining if SA input can properly handle the power*.

If unsure, always begin with a 20dB, even 30dB, attenuator between the LPAS device and the SA input until you can see the waveform and signal level vs. scale. FWIW, I generally use attenuators in multiples of 10 in this application just to keep the math simple.

*So now the obvious question is how does one determine the actual RF power output of a wide band digital device. One has to look at channelized power; that power contained within the defined channel bandwidth of the carrier. Thus, as an example, for an Axient Digital mic, the defined channel bandwidth is 185kHz, and, if your SA has a channel power function, you would set the channel power width to the 185kHz.
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Henry Cohen

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Re: Frequency counter recommendations
« Reply #15 on: December 23, 2021, 05:29:13 PM »


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