Am receiver frequency readout

[Nick]

To get back to the topic in hand why not a cord drive? Assuming there's enough Spindle on the Pot you could use the usual arrangement 'backwards', that is the Cord round the Spindle drives a Drum which has a pointer attached.

Much simpler idea, and probably more appropriate - also allows for the IF offset and for artistic license in the design of the scale...

[Rascal]

Thanks for the many replies and ideas

I should clarify the word 'pot' - it is actually a mult-turn dial (not the original) that drives a slow motion drive (again I don't thinks its original) which ultimately moves an arm a long a coil.

I believe the 2 units involved were originally from a commercial / military receiver. These unit were incorporated into a 'home brew' setup which was ultimately pulled apart and left to gather dust for 40 years. Unit 1 is the tuner etc and unit 2 is the power supply and AF amplifier. Both seem to have been modified/repaired. I seem to remember having some info/circuit somewhere - see if I can hunt it down.

It is continuous tuning (although it overlaps at 110mhz). The multi-turn dial has at least 20/30 turns from top to bottom

To listen - I am running the 21.4 IF output into a Racal RA17L (tuned to 21.4mhz).

I am guessing that probably the original receiver may have had a 2nd if and filters and obviously a detector. The next project!

I did say that I would prefer an analogue meter to display frequency - but I am open to a mechanical dial or further ideas ( I guess that is why I posted). But obviously an idea of frequency would be good (and meter came to mind) - also this should prevent damage to the delicate tuning coil upper and lower mechanical limits.

I am not trying to return this to its original state (whatever that may have been). This receiver is probably circa 1950s/60s , modified/repaired, and pulled apart during the 1960's (brought back to the UK from Ascension island 1968), rebuilt in some fashion during the 70's, and once again pulled apart, finally receiving a new AF output transformer, and a couple of capacitors circa June 2013. Its had a bit of a journey of the last 5/6 decades. Returning it to an authentic state would in my opinion eradicate part of its history. I quite like the idea of vintage mixing with modern.

If interested I will try to provide photos of these units

Thanks again for your ideas and help

Regards Paul

[Refugee]

Would a stack of silicon diodes in series with the meter do the job?

[Joe]

If interested I will try to provide photos of these units

Yes please!

- Joe

[Eddystonepete]

Fascinating Paul. I bet someone would recognise it if you put up a picture! Peter

[Rascal]

               

After trawling the internet last night I discovered the variable tuning coil is called an 'inductuner' most probably by an American company called Mallory.

Seems these were quite popular in television sets that also had AM/FM radio reception.

I have attached the photos of my 2 units. I have removed the inductuner case.

Regards

Paul

[Joe]

The PSU/amp must be homemade as the two transformer should be at 90º to each other.

- Joe

[Refugee]

It looks like it has an audio output transformer that is at 90 degrees if it is the black Phillips by the smoothing cap.

[Joe]

I stand corrected: I hadn't seen that. The second silver-coloured thing must be a choke.

- Joe

[Refugee]

That is exactly what I thought. Have a look at the wiring to confirm it.