Am receiver frequency readout

[Rascal]

I have a 1960's un-cased  'home brew'  valve radio receiver that covers 60mhz to 186mhz. This is tuned by a mechanical mult-turn pot.
 
I have decided to build the receiver into a case. Unfortunately it doesn't have a frequency readout so I thought it would be an idea include some kind of indicator to do this.  I require something that gives me an idea of the frequency it is tuned to - to the nearest 5mhz would be sufficient.

Preferably I would like to use an analogue meter to achieve this.  I have a connection from the local oscillator (frequency + IF of 21.4mhz) - would it be possible to use this?

Any ideas or suggestions would be appreciated.

Paul

[Mr Smiley]

How about a mechanical dial and a scale drawn behind it, tune a station, mark the dial The old way 

Simple   

Remember, the Americans spent millions developing a pen that writes upside down in space. the Russians used a pencil 

[digsys]

  How about a mechanical dial and a scale drawn behind it, tune a station, mark the dial The old way   

It's a multi-turn pot. You could use a 10Turn 3Digit Potentiometer dial ie Vishay Spectrol 15A31B10
Another idea is to have a slave 2nd gang pot that drives a meter. If you have to do it via the circuit, we'd need to see the circuit.

[vk6zgo]

If it uses a pot,it must adjust the bias on a varicap.
Make a high impedance voltmeter & connect it to read the bias voltage.
You can try this with your DMM first to see if is workable.

[Radio Tech]

How about a mechanical dial and a scale drawn behind it, tune a station, mark the dial The old way 

Simple   

That is what I would do. it is old school, I keep it that way.

Remember, the Americans spent millions developing a pen that writes upside down in space. the Russians used a pencil 

rofl!
We americans always seem to go around our elbows to get to our A**
 

[Rascal]

Thank you for your replies.

I used the word 'pot' out of context - apologies. The receiver is tuned mechanically via a multiturn dial through a slow motion drive- the actual mechanism drives an arm along a coil.

Is it possible to use a pre-scaler circuit to divide the local oscillator down to a manageable frequency - then use a LM2907/17 or maybe a ne555 to covert to a voltage?

If possible - any ideas on the pre-scaler circuit?

Thanks again

Paul

[c4757p]

Pencils make conductive dust that floats in microgravity, you'd be a moron to use that.

[vk6zgo]

How about a mechanical dial and a scale drawn behind it, tune a station, mark the dial The old way 

Simple   

That is what I would do. it is old school, I keep it that way.

Remember, the Americans spent millions developing a pen that writes upside down in space. the Russians used a pencil 

rofl!
We americans always seem to go around our elbows to get to our A**
 

Maybe the Americans were worried about pencil sharpener shavings floating around inside the spacecraft!
There is no upside down in space,anyway!

[Radio Tech]

How about a mechanical dial and a scale drawn behind it, tune a station, mark the dial The old way 

Simple   

That is what I would do. it is old school, I keep it that way.

Remember, the Americans spent millions developing a pen that writes upside down in space. the Russians used a pencil 

rofl!
We americans always seem to go around our elbows to get to our A**
 

Maybe the Americans were worried about pencil sharpener shavings floating around inside the spacecraft!
There is no upside down in space,anyway!

Hmmm, you might just have a "point" there

[Mr Smiley]

 

We're veering away from the op question    Sorry about that 

ps, they were pressurized ink cartridges, they half filled them with ink, popped in a ball bearing to create a seal between the ink and the top empty chamber and pressurized the empty section above the ball bearing before sealing the end, so the pressure pushed against the ball bearing and that provided a constant supply of ink, you can still buy them today commercially.

Was it worth millions 

Any way, back to the OP

[AlfBaz]

Wasn't there a whole Seinfeld episode about it?

[kfitch42]

The space pen is really an amazing story of the power of capitalism, not the epic fail that the one-liner would suggest.

http://www.snopes.com/business/genius/spacepen.asp

[Mr Smiley]

I stand corrected   

NOW BACK TO THE OP 

 

[edavid]

The most common way to do this is to use a PIC-based frequency counter which subtracts the IF frequency, for example:

http://www.morsex.com/aade/counter.htm

If you look around, you can find DIY projects using the same concept.  You could adapt one to output PWM to an analog meter instead of using an LCD display.  You would have to add a prescaler also (Or is that frequency range a typo?  It doesn't seem very useful.)

Unless you're really opposed to microcontrollers, it's the easiest and best way to do the job.

[JackOfVA]

Sounds like a Mallory Inductatuner, or a knock-off of Mallory's design.

If the main tuning knob only has one revolution or less then a mechanical dial is a good solution.

If the main tuning knob makes more than one revolution, then the mechanical solution is more complicated. But, perhaps one of the mechanical turns counting dials sold to be used with a multi-turn potentiometer would work. Purchased new they can be a bit pricey but can be found used at a more reasonable price.

For a electromechanical solution, I suppose a multi-turn potentiometer ganged with the tuning shaft and read out with an analog meter would preserve the period nature of the receiver.

[Rascal]

Sounds like a Mallory Inductatuner, or a knock-off of Mallory's design.

Looks very much like a Mallory Inductuner

Paul