BC221 Frequency Meter 

Glad you liked it. Yes, I find it quite surprising just how accurate the thing is after so many years! (Although it does take a while to take the measurement...)

Köszönöm!

Good luck Helen. In my experience, it may well work without any repairs as the units were very well made. You'll need to knock up an external HT and LT supply of course!

Thanks for the positive comments. Glad you found it useful. Are you suggesting that the crystal frequency might be actually wrong, or do you just want to test it? I would like to take our set out to check the questions you ask, but I believe that the crystal switch setting is just the crystal. The easiest way to check that it is actually working at roughly the right frequency would be to pick it up on a radio set tuned to the medium wave with a short wire attached to the aerial pillar. I think that the easiest way to check a low level frequency for its accuracy without an expensive frequency counter, would be to 'beat' it against a similar frequency. In the case of a 1MHz crystal, you could use another 1MHz oscillator or a multiple of this such as 2MHz etc. I hope this helps!

@@lishaton Thanks for your reply, I did manage to find a solution. I set to crystal only and fed a 1 mHz signal from my digital signal generator into the antenna. Then I zero beat using the adjustment on the signal generator. The crystal showed as 1,000,029, so out by 29hz provided what I’m seeing isn’t tolerance in my digital signal generator. Someone else suggested taking a reading at the crystal check point of 1mHz and then comparing to the reading from a 1mHz signal from my generator. Using this method the crystal was very close to the 1mHz signal, within 1 position on the vernier scale.

Interesting! I guess at the end of the day, it's really a case of just how accurate does a frequency reading have to be? All depends on the actual application of course. However, if we were to assume that your digital genny was absolutly spot on, then 29 Hz off after ?? years isn't at all bad!

The sets were designed to work off batteries, which were meant to be housed in the compartments at the back. How can you tell if the valves are ok? Same as with any other valve set I guess! Substitution is one way, a valve tester is another, OR a relatively simple way is to take the valve out and lash together a simple amplifier circuit to actually hear it working. Granted, the valve might work as a simple amp, even though it has certain faults, but as a rule it's a good starting point if you don't have a tester.

@@lishaton Okay I will get a tester in a few days. Will I be able to listen on it? I did notice the headphones are missing. I was looking around online for HeadPhones maybe a DJ headphones will work I'm not sure? TnX You for helping me so much I don't know anything about it.

@Geo’s radio & musical stuff Tnx. All the wires are missing don't know where to connect it too. The one I have was kept by a ww2 soldier and ploit.

@Jack O'Bean Thanks for getting back too me. I don't really know anything about this unit or frequency counter but I think someone said you can used it to do CW but unsure. I think the unit was battery used at the time it was used.

Hi Helen. I seem to recall it is somewhere from about 125KHz to 20MHz. I hope yours still has the book that was made and matched to it, as it will otherwise be almost impossible to use. There is a computer program around that attempts to generate a set of pages of 'settings' for sets where the owner doesn't have the book, but I am not sure just how well it works. As each book was matched to each individual set, the book on its own is useless without the set it was designed to work with.

Oops! Sorry about that. You're right of course!