Confused about Frequency Counters

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Although I used someone's frequency counter back around the 1970s, I
never owned one. From what I recall, back then, there was a BNC
connector on the unit, where test leads connected and were used to
determine the frequency within a radio stage, or used to check the
output from a signal generator.  

I'm looking on Ebay and seeing some costly ones selling for $100 and up,
which have lots of buttons and connectors. -OR- seeing some that are
listed to go from 1 CPS to 70 or 80 MHZ, which tells me that they can
show audio frequencies, and up to the 70 or 80 MHZ limit, which means
they will work for AM radio, many Ham bands, CB radio, but *NOT* FM
radio.  

Then what caught my eye were these inexpensive handheld ones, such as:
http://tinyurl.com/y84hun67

However, these do NOT have BNC connectors. Just an antenna. (No test
lead connector), So, obviously, they can not read audio freqs, and can
not be used to check the stage in a radio, but should probably pickup
the output from a signal generator if the sig gen test leads are held
near the antenna.  

However, this device (above URL) only covers 50 MHZ to 2.4 GHZ. That
means it's worthless for AM radio, CB radio, and many lower Ham bands.
(In my case, this would be pretty useless, since I mostly work on radios
that are AM FM CB or SWR.  

Ideally, something that covered 1CPS to 110 MHZ would be best suited for
my needs, but I cant find anything like that, at least not in the price
range of $50 or less. (which is what I am willing to pay for something I
wont get real much use from).  

My antique Eico 320 Signal Gen only goes a little over 100 MHZ, so once
again, the example URL I posted would not be real helpful.

So, I am pretty confused. What's better, an antenna or test leads?  

Do they actually make and sell LOW PRICED Freq Counters that go from 1
CPS to 110 MHZ or so?  

Then again, it almost appears that to get full coverage of all
Frequencies, a person needs to buy TWO Freq counters, since UHF TV
covers the 470 to 806 MHZ. But once again, what good is a Freq Counter
with no test leads (just an antenna) for use on television?  




Re: Confused about Frequency Counters
On Sat, 27 May 2017 12:55:02 -0400, snipped-for-privacy@tubes.com 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.

Or, maybe one of these variations:
<http://www.ebay.com/itm/Digital-6LED-1MHz-1000MHz-1GHz-RF-Signal-Frequency-Counter-Cymometer-Tester-G-/222009256193
<http://www.ebay.com/itm/1MHz-1200MHz-RF-Frequency-Counter-Tester-Digital-LED-METER-Cymometer-f-Ham-Radio-/331915125484
<http://www.ebay.com/itm/2016-0-91-OLED-RF-1Hz-2-4GHz-Frequency-Counter-Meter-Cymometer-Tester-/172692754650

You can also use a mixer to take a higher frequency signal, and mix it
down to something lower that the counter can handle.  I have some HP
microwave counters that work like that.

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On 28/05/17 04:35, Jeff Liebermann wrote:
Quoted text here. Click to load it

I have two of those. I bought the second because I thought I'd
broken the first, it performed so badly. They're as bad as each
other.

If you have a strong and stable signal, it can work ok, but
the input design is poor. The HF and the pre-scaler both
have dual-gate mosfets, but there's no gain control (automatic
or otherwise) and the inputs are paralleled. I've disconnected
the two inputs by cutting a track and soldered on a little bit
of RG-158 to an SMA connector for the high range.

I'd love it if Mike is willing to share some of his counter
front-end wisdom.

Re: Confused about Frequency Counters
On Sun, 28 May 2017 08:09:04 +1000, Clifford Heath

Quoted text here. Click to load it

Thanks.  I was thinking of buying some of those.  I should have known
as much of the low cost "modules" that I've purchased seem to have
deficiencies as a result of crude design or cost cutting exercises.

To clarify my my comments a little, I was not recommending the
purchase of any of the devices I pointed to on eBay.  I meant them as
examples of devices that have prescalers, which was part of the OP's
rant on requiring multiple counters to cover the frequency range.  My
comment "Something like this:" usually preceeds something that I
haven't worked with.

Quoted text here. Click to load it

I picked that particular example because it has a drawing of the PCB
showing i/o and controls:
<
http://i.ebayimg.com/images/g/hBYAAOSwAPVZGlOn/s-l1600.jpg

It has two adjustments labelled "High channel sensitivity adjust"
which I guess would help with the tiggering.  Do these controls work,
or were they deleted in yet another cost cutting exercise?

Quoted text here. Click to load it

The OP has not disclosed how he plans to use the counter.  If it's a
bench instrument, that requires precision, I suggest any of the
numerous used HP counters available on eBay.  
<https://www.google.com/search?tbm=isch&q=hp+universal+counter
Especially the HP 5300 series:
<https://www.google.com/search?q=hp+5300+counter&tbm=isch
I have accumulated a fair collection of these and find that used
counters are a far better deal than the eBay instruments, such as:
<http://www.ebay.com/itm/Victor-VC3165-Radio-Frequency-Counter-RF-Meter-0-01Hz-2-4GHz-K8M3/122448388056

Incidentally, since the OP is into tubes, my favorite counter is an HP
5248M with genuine Nixie tubes.  Middle right above the spectrum
analyzer:
<http://802.11junk.com/jeffl/pics/home/slides/lab.html
The pile of 4 plugins under the Glad bag box are the various mixer
type downconverters I previously mentioned.  I also have an HP 5245L:
<https://www.eevblog.com/forum/repair/repair-of-hp-5245l-nixie-frequency-counter/?action=dlattach ;attach20%4375;image>
Cheap but scarce on eBay:
<http://www.ebay.com/itm/HP-Hewlett-Packard-5248L-Electronic-Counter-5254C-Frequency-Converter-15-3-0GHz-/182520538437



--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On 28/05/17 14:25, Jeff Liebermann wrote:
Quoted text here. Click to load it

It was developed by a good hobbyist who posted everything online.

I think that full schematics of slightly earlier versions are
available online. He uses a dual-gate MOSFET before the prescaler
and before the main counter, with the inputs paralleled. I think
that affects the sensitivity (though I don't have measurements)
so for my 2nd module, I cut a track to separate the input paths.
I might wind up adding an independent input amplifier with AGC,
or even a pot to adjust the 2nd gate bias on the MOSFETs for a
manual gain control. A little difficult though, as parts of the
circuit are underneath the LED displays, so I'd need to remove
those.

The main counter is a PIC.



Re: Confused about Frequency Counters
On Sun, 28 May 2017 16:13:52 +1000, Clifford Heath

Quoted text here. Click to load it


I couldn't find any such project.  I suspect that it might have gone
the same way as the various M328 component test meters being sold
online.  The original project was open source.  It was then
commercialized by various vendors with wildly varying pricing.  Much
of the stuff I've found was early versions of the board and firmware.
Meanwhile, the project has done on to add features and improve the
firmware, but the online stuff seems stuck with early revisions.  This
link includes some history:
<http://www.instructables.com/id/AVR-Transistor-Tester/
I can't seem to find the original development site, which was in
Germany.

Quoted text here. Click to load it

If the amplifier is used to simply produce a square wave out of
whatever it fed into the input, low gain might be a big problem.  So
will noise around 0v which is why a "threshold" adjustment is usually
supplied.  Getting such a simple amplifier to work from 0.1MHz to
2.4GHz is unlikely, which might explain the lack of sensitivity.

Quoted text here. Click to load it

May I suggest that you remove the input amp and setup something that
give the prescaler a 50 ohm input.  Then, design a broadband RF
amplifier that has a chance of working over the frequency range.
Something similar to a CATV or OTA TV/FM amplifier might be suitable.
However, don't worry about getting a flat frequency response.  Just
take whatever you can get that produces enough drive to make the
MB501L prescaler happy.  A collection of communications freq range
bandpass filters would be nice to prevent triggering on out of band
junk.  

Quoted text here. Click to load it

I'm not PICky.


--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On 29/05/17 02:43, Jeff Liebermann wrote:
Quoted text here. Click to load it

Yes, that seems to describe it.

Google for Sanjian Studio (which is on the PCB) and you'll find
an English translation of the manual. That had assorted URLs to
www.hellocq.net where the many stages of this project's development
was discussed. You have to log in to see the schematics. I subscribed,
but my account seems to have now expired (I didn't get the spam that
I expected from this subscription). So I only have the assorted files
I downloaded, see here:
<https://www.dropbox.com/sh/z91pqvcpg470tuy/AAAIRnVfRDqrbrJwA3yBVQVPa?dl=0

Quoted text here. Click to load it

Yes. High gain is a problem too, causing spurious transitions.

Quoted text here. Click to load it

Yes, except it's meant to be (and mine are) and MB506.

Quoted text here. Click to load it

Good idea.


Earlier schematics show two 4-bit counters before the PIC,
which by itself does not have a 60MHz counter.

Clifford Heath.

Re: Confused about Frequency Counters
On Mon, 29 May 2017 08:45:50 +1000, Clifford Heath

Quoted text here. Click to load it

Got it and thanks.  Nice the way the download is packaged as a single
ZIP file.  The docs are in Chinese.  I haven't tried Google translate
on it yet.  The new schematic is very difficult to read the text.  I'm
also having problems decoding the "forum description".  It's readable
imported into MS Word as Unicode-8.  The photos of the PCB seem to be
the old design, which lack the extra divider chips.  This is going to
be a challenge.

Quoted text here. Click to load it

It also says MB506 on both the old and new schematics.  
<http://www.qsl.net/n9zia/900/mb506.pdf
That's odd because it's a divide by 128 or 256 that goes up to 1.6GHz.
At 2400MHz, divide by 128 yields 18.75MHz.  I originally thought that
it would need to use all of the 60MHz counter frequency range, but now
I'm not certain.  The PIC used is apparently slow, and won't go that
fast.  18.75MHz seems about right for the PIC16F628a where the data
sheet says it quits at 20MHz.
<http://ww1.microchip.com/downloads/en/devicedoc/40044f.pdf>
The ForumDescription.txt file says that it's divide by 64 on the first
page, but then claims that the low channel goes to 75MHz, and later
claims that the prescaler is an MB501.  Kinda looks like the
ForumDescription.txt file is a mixture of the old and new designs.

Looking at the new schematic, I see that one bipolar front end
transistor was replaced by a dual gate mosfet.  However, it doesn't
look like the gates were tied together on the schematic.  The original
schematic is tiny, but after enlargement, I don't see a dot where the
wires cross.

Also, if you follow the signal path through the prescaler chip on both
the old and new schematics, the higher frequency range input goes
through the prescaler, into the DG MOSFET, and then to the PIC
counter.  If there is a sensitivity problem, it would only be on the
lower frequency range input, which goes to the DG MOSFET directly.

Quoted text here. Click to load it

Probably correct, but I can't tell what those are.  Also, I think you
have it backwards.  The older schematic shows no dividers, while the
new schematic shows what I guess are dividers.


--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
wrote:

Quoted text here. Click to load it

I missed the translated user manual (in English).  It shows a
sensitivity graph for the high frequency range with the following
comment from Pg 12:
  It is noted that the UHF channel allows measurements up to about
  450 MHz. This path comprises a divide by 64 stage claimed to be  
  able to operate to 2.4GHz according to the published specifications.
  It is therefore surprising that the sensitivity fell as quickly  
  as it did.
Looking at the schematic and layout, my never humble opinion is that
the designer didn't know anything about RF design and layout.

The schematic shown on Pg 13 is quite different from either the old or
new versions of the design that I previously mentioned.  Instead of
the extra divide by 4 packages, it has a 2nd DG MOSFET in front of the
PIC counter.  It also lists the prescaler as an MB506 which is divide
by 128/256, not 64.  It also shows that the gates of the DG MOSFET are
NOT tied together.

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On 29/05/17 14:51, Jeff Liebermann wrote:
Quoted text here. Click to load it

That was my conclusion also, and that (plus the earlier published
versions) is why I said "advanced hobbyist". Not even very advanced,
certainly not RF-experienced :)

I don't know what frequency the PIC counter input is capable of,
but I know that the AVR counter is clocked; so you can only count
at half the CPU clock frequency. Bah, humbug.

Quoted text here. Click to load it

Both my units have MB506.

Quoted text here. Click to load it

The units I have have both pairs of protection diodes, and the inputs
are joined only at the connector. I cut the trace and soldered a bit
of co-ax onto the prescaler input capacitor.

I don't have a good RF source (yet - currently building, see
https://github.com/cjheath/AD9851LCD ) so I can't evaluate the
sensitivity.

Clifford Heath.

Re: Confused about Frequency Counters
On Mon, 29 May 2017 17:29:44 +1000, Clifford Heath

Quoted text here. Click to load it

The clock crystal is 4MHz on the old version.  I can't read the
numbers on the schematic of the new version.  That doesn't look very
promising for measuring 60MHz inputs or even with /4 at 15MHZ.

Quoted text here. Click to load it


Oh swell.  So the PCB wiring might not follow the schematic.  I
suppose it doesn't matter since the DG MOSFET seems to be badly biased
anyway.

I was having nightmares last night from thinking about this counter.
Maybe I should give up while I'm still sane?

Quoted text here. Click to load it

Before you reinvent the wheel, there are AD9851 based DDS generators
available on eBay.
<http://www.ebay.com/sch/i.html?_nkw=dds+generator+ad9851
along with the associated LCD display:
<http://www.ebay.com/itm/PIC16f-Controller-for-the-AD9851-DDS-Signal-Generator-Module-/182593721953
However, those only go up to about 70MHz and the output looks
distorted above 30MHz.  If you're going to test the counter all the
way to its rated maximum frequency (2.4GHz), you're going to need a
better generator.  DDS has benefits for a function generator and
arbitrary waveform generator, but is limited to lower frequencies.  

This looks interesting (and tempting):
<http://www.ebay.com/itm/ADF4350-v4-0-137-5MHZ-4-4GHZ-OLED-display-Signal-generator-RF-signal-source-12v-/262688224985
137.5MHz to 4.4GHz signal generator in 10KHz steps.  Looks ok to about
1GHz, but drops in output and increases in sidebands at higher
frequencies.  Looks like the same board, but in a shielded box:
<http://www.ebay.com/itm/137-5MHZ-to-4400MHZ-Signal-generator-frequency-generator-RF-signal-source-dc-12v-/271838837908
Or maybe this thing:
<http://www.ebay.com/itm/0-5Mhz-470Mhz-RF-Signal-Generator-Meter-Tester-For-FM-Radio-walkie-talkie-debug-/172598060649
Or maybe something computah controlled via USB:
<http://www.ebay.com/itm/RF-Signal-Generator-35MHz-to-4-4GHz-via-USB-16dBm-Plus-Features-2000-units-sold-/201929990411
Or maybe a real RF generator from HP, TEK, Fluke or others that can
actually be calibrated and trusted.  This is the cheapest HP I could
find:
<http://www.ebay.com/itm/Hewlett-Packard-hp-8656A-Signal-Generator-1-990MHz-rf-signal-generator-04-/252950700229
I have an HP 8656A but prefer to use an HP 8540B.  Top right:
<http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html








--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On 30/05/17 03:16, Jeff Liebermann wrote:
Quoted text here. Click to load it

But I don't think the PIC has a clocked counter anyhow.
I assume that the AVR does it to (sometimes) avoid the
need for a low-pass filter.

The xtal on mine is marked "SCK451C" and "TC,A.426",
whatever that means. It was about 15ppm slow, but seemed
quite stable, based on measurements taken with an HP5386A.

Quite a few people have patched in a TCXO to these units.

Quoted text here. Click to load it

I don't understand why they used a DG MOSFET, nor why, since they
did use one, they didn't use the upper gate for gain control.
It seems they're feeding the signal into the upper gate, so
won't get the best bandwidth from the cascode behaviour.

Quoted text here. Click to load it

I haven't found the schematic of the current-manufacture.

Quoted text here. Click to load it

I think it's fixable, perhaps with an additional front-end.
It would still be easier and cheaper than building from scratch.

Quoted text here. Click to load it

Who do you think designed those? People like me :) I have a bit
of that Jedi "build your own light sabre" thing going on.

Plus there's no accessible used test equipment market here in
Australia. Whenever nice gear comes up at bargain prices,
merchants buy it up and slap a stupid price on it.

Quoted text here. Click to load it

That's exactly what I'm using for development. They have all
copied a flaw in the output filter design, leading to very low
output at higher frequencies. Some impedance problem, it's not
designed to drive 50ohms. I'll add a buffer.

Quoted text here. Click to load it

I loathe and detest both PICs and those 16x2 displays.
I'm building one with 320x240 colour touch screen.

The Arduino also has TTL-level RS232, so add a $2 USB module
and you have USB control.

Quoted text here. Click to load it

I expect to incorporate an ADF4351 also, and possibly two AD9851's,
to give quadrature (but still cheaper than AD9854 or whatever
the multi-channel DDS chip is).

E.g.
<https://www.aliexpress.com/item/35Mhz-to-4-4GHz-4400mhz-PLL-RF-Signal-Source-Frequency-Synthesizer-ADF4351-Development-Board/32757566484.html

The ADF351's have the same problem as most of those VCO synthesisers,
that they won't sweep cleanly. Changing the frequency makes them
jump wildly about until they stabilise again.

Quoted text here. Click to load it

The Arduino clone and TFT Touchscreen LCD cost me $AU14 all up.
<https://www.aliexpress.com/item/2-4-SPI-Serial-TFT-LCD-Touch-Panel-240x320-Dots-5V-3-3V-Module-ILI9341-Driver/32665656357.html
Add the $30 ADF4351, a $17 $AD9851, and USB and you have a nice bundle
for half what the above costs.

Quoted text here. Click to load it

"Does not ship to Australia"

Quoted text here. Click to load it

I have to give this HP5386A back, but not in a hurry - my friend also
has mountains of test equipment. He worked in sat-comms, so has contacts
who call him before dealers get there - but he loves to hoard it all :(

Clifford Heath.

Re: Confused about Frequency Counters
wrote:

Quoted text here. Click to load it

Although I am not willing to spend big money on this, I tend to avoid
those super cheap boards with no cabinets. I dont know how they can even
sell them that cheap, so obviously they are not quality. Not to mention
it costs 5 times the price of the board  to buy some sort of box to put
those boards in, and for all the connectors and stuff. So, by that time
I'd have $25 or $30 invested. I'd rather find a complete unit that is
better quality and eliminate all the hours it takes to put them into
some sort of box. Making boxes and drilling all the holes and that sort
of thing has never been something I am real fond of anyhow.  

I am currently looking at a Hickok 380, several HP counters, and a C&C
150. That Hickok is a BID sale, which means I dont have much of a chance
of getting it. (Being on dialup, I cant place a bid in the last 10
seconds). Normally I dont even bother with bid sales, and just do the
"Buy It Now" items.  

The HPs are all over my price range, but I dont need to buy it today or
even this week. I can wait till I find a better deal. That C&C 150 seems
like a real good deal, (about $39 with shipping), but I have never heard
of that brand so I am looking to see if I can find more reviews of it.
It appears to be a rather high-end device, with lots of features and a
very wide freq range.

My main reason to get a counter is mostly just to check the frequency
coming from my Signal Generator. Having one that also checks audio freqs
would be kind of nice, since I have a tone generator that I'd like to be
able to know the frequencies it's outputting, but that is not an
absolute necessity.

I probably got more use from the Freq counter I used in the 70s (which
was borrowed). Back then I was doing a lot with CB radios and that
counter would check the CB channel output for accuracy. But I dont do
much with CBs anymore, since no one uses them now.



Re: Confused about Frequency Counters
snipped-for-privacy@tubes.com says...
Quoted text here. Click to load it

YOu really need to buy one of the used service monitors.  They can be  
had for around $ 1000.  You get a counter signal generator and many more  
things.  


Re: Confused about Frequency Counters
On 5/28/2017 8:57 AM, Ralph Mowery wrote:

Quoted text here. Click to load it

Like this for example:
<http://www.ebay.com/itm/272688535932



--  
Jeff-1.0
wa6fwi
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
wrote:

Quoted text here. Click to load it

Overpriced.  Look at the prices of the sold listings:
<http://www.ebay.com/sch/i.html?_nkw=Motorola%20R2001&LH_Complete=1&LH_Sold=1

I have two R2001D boxes parked in my palatial office waiting for the
mythical "spare time" needed to fix them.  One has most of the red
LED's on the right bashed in by someone dropping something heavy on
the front panel.  The other has a very weak CRT display, which is
probably an HV power supply problem.  Both have lock problems, which
means it's time for a tantalum transplant.  They've been sitting there
for about 3 years.  If I wait long enough, maybe the owner will forget
I have them.  

I have a few other service monitors.  There are three SSI/Wavetek 3000
series service monitors in this photo, plus one more I recently
acquired.  Typical cost was $300/ea:
<http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html
In the middle left, is an IFR-1500 service monitor (with an
intermittent power supply).  I paid $1500:
<http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html
There are several cell phone specific service monitors hidden in
various corners.

Yep, service monitors are a good thing to have an use, especially in
the field or on mountain top radio site.  It has everything that you
might need to work on radios including a counter.  All have TCXO or
OCXO reference oscillators for accuracy.  At home, I have a home made
GPSDO for even more accuracy.

However, there's a catch.  All the stuff in the photos is from the
1980's which means that components are starting to fail.  It's a
continuous battle to keep these things running and usable.  If you
decide to invest in an older service monitor, be prepared to
occasionally dive in and do some repairs.


--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
On Sun, 28 May 2017 09:57:35 -0400, Ralph Mowery

Quoted text here. Click to load it

I'll pass.....
I'd first have to rob a bank anyhow, in order to pay for it, and I think
the bank clerks would just laugh when I pointed a soldering gun at
them... (Or maybe a glue gun, or a caulking gun)  :)


Re: Confused about Frequency Counters
On 5/28/2017 3:03 AM, snipped-for-privacy@tubes.com wrote:
Quoted text here. Click to load it

Have you been living under a rock for the past 20 years?
<https://www.esnipe.com/


--  
Jeff-1.0
wa6fwi
We've slightly trimmed the long signature. Click to see the full one.
Re: Confused about Frequency Counters
snipped-for-privacy@tubes.com wrote:
Quoted text here. Click to load it

Can't blame you a bit for not jumping on those "kits" mentioned previously.  
Often more trouble than they're worth when you consider all the other stuff  
you have to buy and then all the work to assemble and make work.
The C&C 150 seems like a pretty good deal for you.  Certainly in your price  
range, and appears to be a decent entry level counter.  You can get a manual  
from the manufacturer' web site  
(http://www.cncinst.co.kr/english/bbs/board.php?bo_table=data_eng_manual&wr_id13 %);  
(Registration required, but nothing out of reason, like credit card numbers,  
etc.)

You'll probably find out, if you research "reciprocal counters" (of which,  
this is one) that they offer much better resolution than other "normal"  
counters, especially at low audio frequencies.  This is a good thing, since  
you can select a shorter gate time for the measurement than normal counters.  
If you want to measure an audio tone of, say 123.4 Hz, you'd need to select  
a gate time of 10 seconds to get the last digit to display.  With a  
reciprocal counter, you can select a gate time of 1 second, or even 0.1  
second, and see all the digits the counter can display.  It actually  
measures the period of a signal, and a microcomputer inside the counter does  
a bit of math to calculate and display the frequency with all the digits the  
counter is capable of displaying.

Good luck with your choice,
Dave M  



Re: Confused about Frequency Counters
Or you can just buy something that works.
<https://www.amazon.com/Victor-Precision-Frequency-Counter-Digital/dp/B00MDVN4R0>


--  
Jeff-1.0
wa6fwi
We've slightly trimmed the long signature. Click to see the full one.

Site Timeline