Radio Rentals R216 - UK Vintage Radio Repair and Restoration Discussion Forum

ted_ntsx · 2nd May 2017, 2:05 pm

I have this lovely “Art Deco” looking Radio Rentals R216 that we have now put into regular use in our dining room on a local MW station (its the only radio in my collection that the wife likes the look of!)

It is generally working well with all the usual caps replaced, but a couple of problems have arisen. Every now and again there is a loud “POP” from the speaker, independent of the volume setting. I did notice that when it pops the normally dim dial lamps (in series with the valve heaters) flash brighter, suggesting that the heater current has momentarily increased?

Another problem is that the audio seems to become very slightly distorted after running for an hour or so. Could this be the UL41 running into grid current?

The chassis appears to be a Baird 208

Ted.

Steve_P · 2nd May 2017, 3:44 pm

It is possible that it is, yes. UL41's are known for it Even after you have changed THAT capacitor.

Check bulb sockets, valve sockets and position of any wiring. This could be the UL41 as well as they take a high voltage and there could be an intermittent short in the valve.

Cheers,

Steve P.

ted_ntsx · 3rd May 2017, 6:48 am

Thanks.
The bulb and valve sockets seem fine, and wiring is in good condition. I have rummaged through my box of old valves that was "buried" in the garage, and have located what appears to be a NOS UL41 !
I will fit that later today and see what occurs.

Ted.

peter_sol · 3rd May 2017, 1:29 pm

could be the UY41 flashing over intermittently

ted_ntsx · 4th May 2017, 6:37 am

I have now replaced the UL41 and the UY41.
Ran it for a few hours and heard one loud "Pop", but of course MW is always prone to such noises so it could have been external. It's only if I am actually watching that I can see the bulbs flash brighter when it "pops".

I will run it again today and see what occurs.

Looking more closely at the circuit, it seems that the bulbs are in the mains return line, not just in the heater chain, so any increase in HT current would also increase the current through the bulbs, so could another possibility be arcing inside the smoothing capacitors (which are original) ?

Ted.

peter_sol · 4th May 2017, 10:12 am

unlikely to be smoothing caps

Boater Sam · 4th May 2017, 1:45 pm

Bulbs in radios were often under run to extend their life. When you get a pop it will draw a little more current form the mains, as the bulbs are not at full temperature any slight disturbance in the voltage will cause a visible change in brightness.
I don't think it is anything to be concerned about.

ms660 · 4th May 2017, 1:54 pm

The pop and the bulbs glowing brighter at the same time could be a heavy load switching off on the mains supply.

Lawrence.

2nd May 2017, 2:05 pm	#1
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Radio Rentals R216 I have this lovely “Art Deco” looking Radio Rentals R216 that we have now put into regular use in our dining room on a local MW station (its the only radio in my collection that the wife likes the look of!) It is generally working well with all the usual caps replaced, but a couple of problems have arisen. Every now and again there is a loud “POP” from the speaker, independent of the volume setting. I did notice that when it pops the normally dim dial lamps (in series with the valve heaters) flash brighter, suggesting that the heater current has momentarily increased? Another problem is that the audio seems to become very slightly distorted after running for an hour or so. Could this be the UL41 running into grid current? The chassis appears to be a Baird 208 Ted. Attached Thumbnails

2nd May 2017, 3:44 pm	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Radio Rentals R216 It is possible that it is, yes. UL41's are known for it Even after you have changed THAT capacitor. Check bulb sockets, valve sockets and position of any wiring. This could be the UL41 as well as they take a high voltage and there could be an intermittent short in the valve. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

3rd May 2017, 6:48 am	#3
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Radio Rentals R216 Thanks. The bulb and valve sockets seem fine, and wiring is in good condition. I have rummaged through my box of old valves that was "buried" in the garage, and have located what appears to be a NOS UL41 ! I will fit that later today and see what occurs. Ted.

3rd May 2017, 1:29 pm	#4
peter_sol Octode Join Date: Aug 2003 Location: Welwyn Garden City, Herts. UK. Posts: 1,906	Re: Radio Rentals R216 could be the UY41 flashing over intermittently

4th May 2017, 6:37 am	#5
ted_ntsx Pentode Join Date: Jul 2008 Location: Winterton-on-sea, Great Yarmouth, Norfolk, UK. Posts: 137	Re: Radio Rentals R216 I have now replaced the UL41 and the UY41. Ran it for a few hours and heard one loud "Pop", but of course MW is always prone to such noises so it could have been external. It's only if I am actually watching that I can see the bulbs flash brighter when it "pops". I will run it again today and see what occurs. Looking more closely at the circuit, it seems that the bulbs are in the mains return line, not just in the heater chain, so any increase in HT current would also increase the current through the bulbs, so could another possibility be arcing inside the smoothing capacitors (which are original) ? Ted.

4th May 2017, 10:12 am	#6
peter_sol Octode Join Date: Aug 2003 Location: Welwyn Garden City, Herts. UK. Posts: 1,906	Re: Radio Rentals R216 unlikely to be smoothing caps

4th May 2017, 1:45 pm	#7
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Radio Rentals R216 Bulbs in radios were often under run to extend their life. When you get a pop it will draw a little more current form the mains, as the bulbs are not at full temperature any slight disturbance in the voltage will cause a visible change in brightness. I don't think it is anything to be concerned about.

4th May 2017, 1:54 pm	#8
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Radio Rentals R216 The pop and the bulbs glowing brighter at the same time could be a heavy load switching off on the mains supply. Lawrence.