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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 20th Jan 2019, 1:30 am   #1
Bazz4CQJ
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Default Circuit; Roberts RP20 Radio

I wonder if anyone has this circuit; I cannot find any reference to this radio (except for images) on the internet. This model dates back to about 1990 (?) is transistorised and probably of far-eastern construction. It has 6 push-button tuning pre-sets and six small pots on the front panel to select the station (LW/MW/FM). I bought this new and the sound quality is good for the price they sold for.

Something seems to be awry with the varicap tuning; it now drifts like mad when first switched on, probably taking 20 minutes to settle fully.

Any help appreciated.

B
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Old 21st Jan 2019, 6:35 pm   #2
PJC58-Hythe
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Default Re: Circuit; Roberts RP20 Radio

There is service data for sale her...

https://www.ebay.ie/itm/THE-ROBERTS-...item21513925eb
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Old 21st Jan 2019, 10:56 pm   #3
Bazz4CQJ
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Default Re: Circuit; Roberts RP20 Radio

Ooh..well spotted that man! I had found some old ebay ads for the data sheets only (which I think is really a marketing brochure) being offered to Roberts collectors, but this guy is obviously providing the circuit diagram too.

At the moment, I'm guessing that there is one or more electrolytics in the circuitry providing (stabilised) DC to the varicaps which are now in bad condition and causing the voltage to change as they "settle down" after switch-on. I'm also wondering whether there is a thermistor in there.

I actually have two of these radios and both are 'like new' despite their age, and are in daily use receiving feed from my pantry Tx.

Thanks Peter

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