Melody 16 Tube Radio - VHF Tuning, OIRT to CCIR Conversion, Diagram Found, Costs & Process

Question

I found a similar topic, but it was about a diagram.
https://www.elektroda.pl/rtvforum/topic2030034.html

I have such a radio in the attic and today I found a diagram for it

Gentlemen, can this tube radio be tuned?
I would like it to play.
Is it possible to use the VHF converter for retuning from OIRT to CCIRT?

I will be grateful for information on how to do it and possible costs.

Krzysztof Kamienski · Accepted Answer

After all, such a VHF head on the ECC 85 is very easy to tune to VHF 88-108 Mhz. FM signal generator, dielectric screwdriver and a little patience.

kris8888 · Accepted Answer

I'm afraid that just a screwdriver and unscrewing the cores is not enough, and tuning the tube head, contrary to appearances, is not so trivial. The easiest way would be to unwind 2 coils from the coils in which the cores move while tuning the VHF band. I do not know the exact design of this head, but if it was possible to get to these coils without damaging the head and tentatively unwind 1 turn, and if it does not get enough, then one more turn, there is a chance that the head will play in the CCIR band.

aksakal · Accepted Answer

Friend, Photo detector! If you are not experienced in tuning, use a converter better, but use a 2-3 band converter, otherwise you will be able to accept less half of the band - because the bandwidth of the OIRT is 8 MHz (65 - 73), and the CCIRT - 20MHz (88-108). I'm afraid that changing only the number of coils will not protect the 20MHz streak. You should know how the scheme of similar heads works. Not everything as simple as it seems at first glance. When changing elements, the balance of the diagram will move, with all possible consequences.

Darek.S · Accepted Answer

If this radio is tuned with a Variometer (and it probably is, because I have not done many tube radios, but I have not encountered any other VHF tuning method), I also recommend the converter. Unwinding the coils from the variometer will not be easy (it has to be dismantled) and probably after unwinding the inductances they will not change as concurrently as in the original one, therefore we will not ensure proper alignment of the heterodyne and input circuits in the entire tuning range.

Fotodetektor · Answer

Can you indicate which one to buy and will there be a scheme with it? I used to tune with an VHF converter and here I do not know too much.

Krzysztof Kamienski · Answer

Are you kidding your friend? Buy a signal generator to retune one radio ???? Probably someone from my colleagues will come and describe this process, which takes place by unscrewing the cores from the coils of the input amplifier and heterodyne, maybe in the extreme case of replacing three capacitors at a cost of PLN 1

Fotodetektor · Answer

Thanks for the help.

Radiowiec 2 · Answer

There is one more possibility. Get yourself a radio from the show from the former East Germany for pennies for parts. those heads were CCIR, tuned with capacitors and tubes. inserting one instead of the other is a minor adaptation. And after the topic.

Tomek Janiszewski · Answer

I re-tuned the Simfonija A Yugoslav radio, but it was only about extending the old CCIR range (87.5MHz-100MHz) to the modern one (87.5-108MHz). In that case, it was enough to replace the brass tuning cores (5mm) with thicker ones (6mm, as it turned out - even a bit too thick). And making new carcasses, the old ones broke when trying to ream: It will undoubtedly also be necessary to replace a few capacitors, especially those in the heterodyne capacitive divider. Unfortunately, in the case of DEA heads, this usually results in thermal instability for the first several minutes after switching on. However, I would not care too much about concurrency: the relative VHF tuning range is so narrow that it can be easily achieved with the help of trimmers.

TELEWIZOREK52 · Answer

It concerns the Symfonij head. It's a pity, Tomek, that you didn't try to insert cores of the same diameter but from a different piece of brass. Once I was surprised how after replacing one brass core with another with the same dimensions, the head drove away about 2MHz. After the original was inserted, everything returned to normal. I replaced it because the thread on the tip was damaged. Brass is not equal to brass, even in a scrap yard.

Melody 16 Tube Radio - VHF Tuning, OIRT to CCIR Conversion, Diagram Found, Costs & Process

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