Frequency of NE602.

Hello.


I finally got my NE602’s the other day, ok so they turned out to be SA612’s but I’m not complaining because they seem to work the same. My question is after tinkering with these chips and building some radios with them I realized they come with a built in oscillator so there for I should be able to use a frequency meter (or what ever you call them in your part of the world) to read the frequency that the SA612 is working at?

Am I right in my assumption and if I am, how would I do this?

Dawn.

P.S. I figure seeing the basis for all NE602 / SA602 or SA612 circuits are the same someone might be able to answer this without me needing to draw up the circuit of what I’m using but if that’s not the case just ask me and I’ll post it.

Thanks in advance.

You would use a buffer on pin 7 of the SA612. They show typical buffer circuits in figure 8 of the datasheet. You would connect your frequency counter to the point labeled "to synthesizer".
Datasheet:
https://www.datasheets.org.uk/pdf/2993892.pdf

I tried the idea in the datasheet and it didn't work... I wonder if there is something wrong with my circuit.

Dawn.

Did the frequency counter read zero or did it read out a number you didn't expect? Try measuring the levels with a RF probe or a scope if you have one that works at those frequencies.

frequency counter read zero... And at the moment I don't own a scope, I was looking into buying one but all I can find in my price range is a 10khz one.

Dawny said:

P.S. I figure seeing the basis for all NE602 / SA602 or SA612 circuits are the same someone might be able to answer this without me needing to draw up the circuit of what I’m using but if that’s not the case just ask me and I’ll post it.

Click to expand...

Now would be a good time to post a schematic of your circuit.

Dawny may not be able to connect a frequency counter directly, -- she should pick up signal on pin7 of the device witha 1KpF capacitor, wireup a 2n2222 or BF495 as a common emitter amplifier- take output at the collector and try to measure with a Frequency counter.

ONce she is sure of the range of the oscillator with say L-C combination and the coil and Trimmer cap are adjusted, she can use normal pointer radio method -- Frequency counter is not a must.

She should appreciate as to how earlier radio biulders have tuned and calibrated their rados across a pointer scale. I do agree a freqiency counter facilitates very much.
Now a days, one could salvage a digital radio like Kchibo KK939B sold very cheap. recover the counter from there and use it with suitable protection-as otherwise the front end burns off. this counter works at very low DC voltages. Datasheets for the COB used there in are downloadable.

Ps:modified after seeing Dawny's reply!

She, I'm a she.

Dawny said:

She, I'm a she.

Click to expand...

It's alright, we won't hold it against you!