Hi
I am looking for ideas how to build a amplifier for a RF Frequency counter. the frequency counter requires 60mv ptp to operate properly.
Some of the frequencies I wish to measure are less than 60mv. I have looked at single transistor amps as well as op amps .
My input would be 5mv and the frequency range from 1khz to 440mhz ( I know thats a big spread)
Any ideas or suggestions would be appreciated
Simple is key
George

 

Hello,

Did you ever think of MMIC's?
ERA and MAR MMIC's

Bertus

 

Hi
I am looking for ideas how to build a amplifier for a RF Frequency counter. the frequency counter requires 60mv ptp to operate properly.
Some of the frequencies I wish to measure are less than 60mv. I have looked at single transistor amps as well as op amps .
My input would be 5mv and the frequency range from 1khz to 440mhz ( I know thats a big spread)
Any ideas or suggestions would be appreciated
Simple is key
George

There are designs online, but take a bit of perseverance to find, its probably best to search on counter schematics and copy the front end you like best.

If you go the discrete component route - the easy route to semiconductors is old TV tuners.

US tuners would have to be at least VHF high band - UK TV hasn't used VHF for decades, any band IV/V UHF transistors will get the job done.

Its pot luck whether the tuner uses BJT or DG MOSFETS - both have pros & cons.

US high band transistors will probably have to be used in grounded base configuration - UHF transistors might let you get away with common emitter. Grounded base has a high output impedance and no current gain, so you need something that can work as a buffer.

The DG MOSFET is more or less a casc-ode stage - you can copy that idea with a JFET/BJT hybrid - there's not that many advantages, but you know better than me whether they're any good to you.

 

Thanks Ian & Bertus

I found a circuit from a frequency counter and will give it a shot found most of the parts in my junk box.
One question the supply voltage to the circuit is set for 5 volts, I would like to use 12 volts, I see the transistors are rated at 40v???
Think it will have much effect? should i put a resistor in series to drop the voltage?
Thanks
George

 

Hi again

I built my amp and it worked using a DDS signal generator but does not work using a RF signal generator, I know the DDS is a voltage sine wave were as RF is different type of energy. Any Help would be appreciated.

Thanks
George

 

Hello,

What is the frequency range of the DDS and its output voltage?
Also what is the frequency range and output voltage of the RF generator?

Bertus