Can this frequency counter measure lower frequencies

Thread Starter

circuitfreak2000

Joined Apr 7, 2015
39
I was thinking about getting this frequency counter


But now that I looked closer and thought about it I see a problem with this one. Apparently it can only measure 50Mhz + and I plan to build some RF circuits using crystals, some below 30 Mhz.

Can this device pick up the frequency or will it only start working at 50Mhz or above? If it can't, that would be a bummer.
 

DickCappels

Joined Aug 21, 2008
10,152
Probably not reliably. There are counters and prescalers that cannot operate below a specified frequency because of their design.
 

DickCappels

Joined Aug 21, 2008
10,152
Well, not exactly 50 MHz. I have a frequency meter that uses a 1.1 GHz prescaler that is rated for operation between 100 MHz and 1.1 GHz. When I try to drive it at frequencies much below 100 MHz (about 80 Mhz from memory) I get random counts.

If the frequency meter in your post could reliably work below 50 MHz, wouldn't the maker want to advertise that fact?
 

Thread Starter

circuitfreak2000

Joined Apr 7, 2015
39
Well, not exactly 50 MHz. I have a frequency meter that uses a 1.1 GHz prescaler that is rated for operation between 100 MHz and 1.1 GHz. When I try to drive it at frequencies much below 100 MHz (about 80 Mhz from memory) I get random counts.

If the frequency meter in your post could reliably work below 50 MHz, wouldn't the maker want to advertise that fact?
You are right. I just had a glimpse of hope that it would show some results even if not 100% accurate.
 

Thread Starter

circuitfreak2000

Joined Apr 7, 2015
39
For about twice the price I found this frequency counter that works from 1Mhz +.



Specification :

Response time : 0.2s
Auto power off time : 80s
Frequency range : 1Mhz---2400Mhz
RF power range : 0.1W---50W
Current consumption : About 100mA
Impedance input : 50Ohm accuracy : +/- 10% when the frequency is 140Mhz~170Mhz,400Mhz~470Mhz
Working tempreture : 0~40°
Battery : 1.5V(AAA) x 3

Do you guys think this one can detect the frequency of RF crystal transmitter reliably? It also shows the signal power which is great. I looks a heck more pro than the other one.
 

Thread Starter

circuitfreak2000

Joined Apr 7, 2015
39
If you have 100 mw of RF then it should be able to work. Maybe what you really need is a frequency meter that doesn't use an antenna.
http://www.ebay.com/itm/High-Accura...ester-measurement-For-ham-Radio-/121521690969

Note: I am not associated with the seller of the item in the link above.
You can compare the RF circuits that I want to create to ones for RC cars and things like that. I believe they generate a pretty strong signal since they work over meters away. Would it be enough for the 1 Mhz + Frequency counter I showed above to pick up?
 

ian field

Joined Oct 27, 2012
6,536
That's a very interesting idea! How would you go about multiplying the output signal?
Probably with a PLL and a frequency divider, the PLL contains a VCO which you divide down to similar to the frequency you want to measure. The phase comparator locks and feeds pulses to a LPF, whose output voltage controls the VCO.

The VCO is of course running at divider times the measurement frequency - so you use the high range counter to measure that.
 

Thread Starter

circuitfreak2000

Joined Apr 7, 2015
39
Thank you for all the comments guys. I think in the end it's just better to dish out the extra $15 bucks and get a decent frequency counter that works from 1 MHz +. :rolleyes: This is the one I chose. Looks like a beaut.

 

ScottWang

Joined Aug 23, 2012
7,397
The price of GY561 comparing to the GY560 is over triple, Just for that 1M~50Mhz band, the price is so difference and more expensive?
 

DickCappels

Joined Aug 21, 2008
10,152
Most likely (IMO) the high frequency version uses inexpensive parts that are mass produced for telecommunications that don't usually go VHF, but the low frequency version use smaller building blocks possibly like the 74HC series, etc. resulting in the need to use more parts.
 
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