neckermann: WR8651; Can the FM range be increased?

Is it possible in any fairly simple way to increase the FM range of this radio?

Since buying it, I have manged to get it working by freeing up the controls which were completely seized. 

I now find that I cannot receive the UK`s Classic FM radio station which transmits at between 99.9 & 101.9 Mhz; clearly beyond the radio`s present range.

I now want to use the radio on a permanent basis as it is one of the few operating examples of Bakelite radios which I have & will fit in the available area.

I have already requested the schematic for the WR8651 from the RMorg which I will need if I am to modify the circuit in any way.

Thanks in advance for any assistance.

graham guy

• Neckermann WR8651 (143 KB)

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As a general principle it's reasonably straight forward to shift the band tuned up or down a little (by increasing or decreasing RF and LO inductance) or decrease the tuning range by adding capacitance on the Local Oscillator and RF tuning.

But to increase the overall span (tuning range) may not be possible at all as that means increase in the ratio of minimum and maximum capacitance of the LO and RF tuning. This might require a different mechanical tuning capacitor. If the tuning range has be deliberately reduced in the design to less than what the mechanical variable capacitor can do then there will be parallel and possibly serial capacitors connected to the RF tuning and LO tuning sections of the mechanical variable capacitor. These should be obvious.

The small "trimmer" capacitors on the main tuning unit fine tune the RF & LO tracking and would normally at least setting not increase range much.  Additionally if you do increase the tuning range then good RF & LO tracking may not be possible.

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I'm not sure I completely understand the question. When you refer to "range" are you referring to frequency range, or distance? I think Michael assumed you were referring to frequency range, but radio stations at 99.9 and 101.9 would be in the middle of the band for almost any country (I think) and hence, any receiver. What is your distance from the stations you mention?

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At least in Germany (region 1), and also for the radio sets produced here, the original UKW FM frequency range had been 87.5 to 99.9 MHz. 

Later on, the range was enhanced  from 87.5MHz to 104.0 MHz, and finally it became 87.5 to 108.0 MHz.

This may be different from the situation in "the americas" (region 2).

The set in question is from 1953, and therefore the FM range 87.5 to 99.9 MHz for domestic models.

The range of distance for reception of UKW FM stations too is a quite interesting question. In the '70s I made those experiments which are documented here (in German). Please compare the map and the list of frequencies in this thread which are 87.5 to 99.9 MHz. Nevertheless, the antenna sold for long distance UKW FM reception had a range 87.5 to 108 MHz.

However, UKW FM long distance reception is no longer of such vital interest as it had been formerly because the programs are also distributed by satellite (Astra & Eutelsat).

Regards,

Dietmar

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Robert/Michael,

                      I must apologise for not making myself clear, but also more importantly for getting it wrong in the first place! The Neckermann does in fact cover the full FM range I require; the problem was a mechanical one in that the FM range does cover the higher frequencies, the drive was sticking through part of the range, and it has now freed itself sufficiently to cover the required frequencies with no intervention on my part.

The tuning dial is curious from my experience: it goes from 2 to 43 rather than the more usual 80 to 110 or thereabouts which is probably usual with German radios but it is the only instance I have come across this.

Anyway, thanks for you input, and again my apologies for getting even the question wrong!

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2 to 43 are the FM channel numbers. Ch 2 is 87.6 MHz, and Ch 43 is 99.9 MHz.

Some dial glasses of old sets were marked by channel numbers rather than by frequencies.

See also the UKW FM Channel Raster (in German).

Regards,

Dietmar

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The numbers from 2 to 43 are channels. In the TV range we usually talk about channels rather than frequencies. For FM radio this is unusual, but it has the same meaning. You can find these channels on other radios too, for example the Nordmende rt1052 has both frequencies and channels on its dial.

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There are very early sets for the "west" that only did up to 100MHz (maybe only UK), and later 104MHz rather than 108MHz, but even a 100MHz set should work for the Given frequencies.

Japan uses 76MHz to 90MHz (or did) and thus "import" S/H Jap cars had a problem with the radio. Adaptors (frequency shifters) where sold but these created problems in areas with many stations.

Eastern Europe /Russia  mostly used 65.8MHz to 74 MHz.

I was somewhat puzzled by the question but assumed the station was just outside the 100MHz. Though usually sets do up to 500KHz above and below the stated range on VHF-FM (UKW).

Personally I've only encountered the 88 ... 104, 87.5 ... 108 and 76 ... 90 MHz sets. Apart from the cheap  radios claimed to do TV sound or Airband and may do 68MHz to 120MHz or 86MHz to 139MHz all in one band (poorly!). Iv'e had a couple of those.

I have seen Channel Numbers, but only on German radio set and also on a photo of an Ukrainian seller's Russian set the VHF-FM was obviously the OIRT 65 MMz to 74MHz but only labelled in "metres" on the dial scale. Well known to Radio Amatuers as the 4m band now (A small 70MHz allocation now in many Western European countries).

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Now I've learned something too. I knew that the FM band frequency ranges varied in different countries, but I had thought that they all went above 100MHz in Europe.

Regards,

Bob

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