Roberts R200
Written by Bryce Ringwood   
The Roberts R200 and R300 date from 1960 to 1964 and exist in several versions. They are popular models because of their style. There are fairly identical looking modern Roberts radios, featuring FM and DAB reception (Yet to be introduced in South Africa). Construction is wood with an artificial leather covering (Rexine ?).
 
Roberts R200 AM/LW Receiver

Frequency Coverage

 
MW 200 to 550 metres (.545 to 1.5) MHz
(Radio Today on 1.485 is tuneable at the end of the scale)
LW - Unknown - Stations are marked on the dial. Possibly 1050 to 1800 metres (approx 150 to 300 kHz).
 

Controls

 
Wavechange/On-Off switch, Tuning, Volume. The set can be rotated for best reception.
 

Circuit

 
6 - Transistor superhet  using PNP germanium AF117 or OC44/45 types in early versions and OC81D and 2xOC81 in the audio. Earlier R200 may use OC78 types. Operation is from a single PM9 battery, readily available in South Africa. I.F is 470kHz.
 
See example superhet circuits - 1950s tranny. The service manual is readily available on the Internet.
 
Roberts R200 - Early Model
 
Inside the Early Version of the Set.
Note the enormous Ferrite Rod Antenna
 
Inside a late model Roberts R200
Later Models had a cutaway PCB and rectangular IF Transformers.
AF117 transistors were used in the early stages.
 

Faults

 
Much has been written about tin whiskers growing inside AF117 transistors. If servicing yourself - you might as well quickly check the shield is not shorting to other terminals, or better still use the multimeter's diode check function to see that the transistors are basically O.K. Faulty transistors should be replaced - modern PNP silicon types may work. Some germanium PNP transistors are available from Mantech - they are very expensive in South African terms.
 
Having got that out of the way, clean the ON/OFF band change switch. 
 
When I did this, one R200 came to life. The other had an obscure fault - a polyester capacitor 180 volts working had developed a short circuit.
 
I did not fiddle with the alignment as it can lead to broken ferrite cores and much wailing and gnashing of teeth.
 

Conclusion

 
These sets are justifiably very popular among vintage radio enthusiasts, particularly the British - and even among the general public, who like them for their stylish appearance. The sharp eyed among you will have noticed how popular they are in UK kitchens, I'm sure every TV chef or chefess has one - although it is principally the modern version tucked away in some corner. Sound quality is good from the 6 inch "Rola" loudspeaker. The set has a rotatable plastic stand, so it can be pointed at the station it is tuned to. 
 
Long Wave is no longer used in South Africa - so all you will hear is a few beacons. (perhaps). There are still several community radio stations on Medium Wave. 
 
 
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