2 top caps - UK Vintage Radio Repair and Restoration Discussion Forum

raditechman · 21st Oct 2012, 2:20 pm

Someone asked me to service this radio chassis some time ago, and now the Autumn is here I may start on it. Before doing so I have posted a picture as it has valves with 2 top caps, I do not remember coming across that type before. There is no cabinet with the set so I have no idea as to make or model. Has anyone else seen a radio with 2 top capped valves?
John

Cobaltblue · 21st Oct 2012, 2:27 pm

Hi John

It's probably a kit set or maybe a low volume manufacturer using war surplus.

The vales are probably something like these

Good luck, it looks interesting!

Cheers

Mike T

paulsherwin · 21st Oct 2012, 3:38 pm

Agreed, they're probably E1148s as used in a number of wartime VHF transceivers. They rapidly became obsolete after the war and vast numbers appeared on the surplus market. I have a cheap 1950s signal generator built around two of them.

They're quite pretty when the heaters are glowing

raditechman · 21st Oct 2012, 6:23 pm

Sunday evening. I've just returned home, thank you for the useful reply's. It may well be a kit radio, I hope to start on it on Tuesday as I have a GEC BC4655 to finish first.
I have attached a picture of the front dial of the "2 top cap set" which may help further with any identification, and I will report my progress when I start to bring it back to life.
John

Herald1360 · 21st Oct 2012, 7:41 pm

Does that small lettering on the bottom of the dial say anything useful?

raditechman · 22nd Oct 2012, 9:52 am

The writing at the bottom of the dial says "CELLGRAVE C/P". I think this is just the manufacturer of the dial, as the Cellgrave name has cropped up before in this forum, in a thread about the dial of a Decca set.
Two of the valves have "REME inspected 1953" on them plus an arrow, so maybe a kit, or home made, from war surplus.
It is bit of a mess under the chassis with some wires cut off, so a circuit diagram would have been handy.
Will be good to hear it working again.
John

mark pirate · 22nd Oct 2012, 10:29 am

"CELLGRAVE C/P" is the name of the dial manufacturer. I am pretty sure that it is a homebrew chassis, the knobs are another clue to its origins of war surplus components.

I have a home made set complete with home made cabinet. It dates from the 40's, luckily it is in working order and well put together. Radios were both scarce and expensive after the war, so it made good sense to build your own from whatever was available at the time.

Mark

raditechman · 28th Oct 2012, 5:16 pm

Just an update.
I have now rewired the output stages (which had wires cut off). It has push pull output. The audio stages are working fine now, and the gramophone pick up works. One of the three CV6 type valves is faulty, (no heaters) and the owner has ordered a replacement valve. Hopefully when that arrives I shall hear some stations!
When so I shall post again.

Heatercathodeshort · 28th Oct 2012, 5:34 pm

Just a thought. I wonder if the dial is made of Celluloid? Might be fun if the dial bulbs got a bit hot. Looks nicely made. Should sound good. John.

Herald1360 · 28th Oct 2012, 6:05 pm

Sounds like it might be. "Cellgrave" is likely a contraction of "celluloid engraver". Of course they may well have engraved other materials as well.

Circuit wise, what do the three oddities actually do? The rest of the set seems conventional enough with normal looking frequency changer, IF, output and rectifier valves but then there's the three triodes...... are they detector, audio preamp and phase splitter or something more unusual?

raditechman · 2nd Nov 2012, 12:41 pm

I managed to get to work on this chassis again Friday morning. The radio chassis now works!
The three 2 top cap CV6 valves were in the audio stages, pre-amps and splitter. I managed to repair the one with no heaters by re-soldering/refitiing the valve base. Although the owner has supplied me with a new valve. There were 9 leaky capacitors to replace, all 0.1mfd expect for one at 0.05mfd, I think the builder of this radio had plenty of 0.1mfd's in stock.
It still did not work, I injected an IF frequency to that stage and the IF was fine. Just the mixer/osc. to sort out. The valve used here is a VR99 and I found a wire hidden behind the wavechange switch going nowhere, after some circuit chasing I deducted where it should go and was rewarded with a lovely sounding radio. Long medium and short waves
Apart from the valves above chassis, this radio also has a VR92 diode below chassis.
It is working very well and I am surprised at how good it performs and sounds,- so I shall keep it for a few days and use it before giving it back to the owner!

HamishBoxer · 2nd Nov 2012, 1:09 pm

The knobs look very similar to CR100 type.

raditechman · 2nd Nov 2012, 1:49 pm

I agree about the knobs being like CR100 Hamish, apparently the owner of this home brew radio acquired it when he was purchasing an R1155 (of which he now has seven) so I think it was probably built by someone in the RAF, it may have been used in a Mess Hall or somewhere as it has a good push-pull audio output stage, and several speaker sockets. Plus gramophone pick up. It certainly has a punchy output. It is on at the moment.
John

21st Oct 2012, 2:20 pm	#1
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	2 top caps Someone asked me to service this radio chassis some time ago, and now the Autumn is here I may start on it. Before doing so I have posted a picture as it has valves with 2 top caps, I do not remember coming across that type before. There is no cabinet with the set so I have no idea as to make or model. Has anyone else seen a radio with 2 top capped valves? John Attached Thumbnails

21st Oct 2012, 2:27 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,869	Re: 2 top caps Hi John It's probably a kit set or maybe a low volume manufacturer using war surplus. The vales are probably something like these Good luck, it looks interesting! Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

21st Oct 2012, 3:38 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,949	Re: 2 top caps Agreed, they're probably E1148s as used in a number of wartime VHF transceivers. They rapidly became obsolete after the war and vast numbers appeared on the surplus market. I have a cheap 1950s signal generator built around two of them. They're quite pretty when the heaters are glowing

21st Oct 2012, 6:23 pm	#4
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: 2 top caps Sunday evening. I've just returned home, thank you for the useful reply's. It may well be a kit radio, I hope to start on it on Tuesday as I have a GEC BC4655 to finish first. I have attached a picture of the front dial of the "2 top cap set" which may help further with any identification, and I will report my progress when I start to bring it back to life. John Attached Thumbnails

21st Oct 2012, 7:41 pm	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: 2 top caps Does that small lettering on the bottom of the dial say anything useful? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

22nd Oct 2012, 9:52 am	#6
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: 2 top caps The writing at the bottom of the dial says "CELLGRAVE C/P". I think this is just the manufacturer of the dial, as the Cellgrave name has cropped up before in this forum, in a thread about the dial of a Decca set. Two of the valves have "REME inspected 1953" on them plus an arrow, so maybe a kit, or home made, from war surplus. It is bit of a mess under the chassis with some wires cut off, so a circuit diagram would have been handy. Will be good to hear it working again. John

22nd Oct 2012, 10:29 am	#7
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Re: 2 top caps "CELLGRAVE C/P" is the name of the dial manufacturer. I am pretty sure that it is a homebrew chassis, the knobs are another clue to its origins of war surplus components. I have a home made set complete with home made cabinet. It dates from the 40's, luckily it is in working order and well put together. Radios were both scarce and expensive after the war, so it made good sense to build your own from whatever was available at the time. Mark

28th Oct 2012, 5:16 pm	#8
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: 2 top caps Just an update. I have now rewired the output stages (which had wires cut off). It has push pull output. The audio stages are working fine now, and the gramophone pick up works. One of the three CV6 type valves is faulty, (no heaters) and the owner has ordered a replacement valve. Hopefully when that arrives I shall hear some stations! When so I shall post again.

28th Oct 2012, 5:34 pm	#9
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: 2 top caps Just a thought. I wonder if the dial is made of Celluloid? Might be fun if the dial bulbs got a bit hot. Looks nicely made. Should sound good. John.

28th Oct 2012, 6:05 pm	#10
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: 2 top caps Sounds like it might be. "Cellgrave" is likely a contraction of "celluloid engraver". Of course they may well have engraved other materials as well. Circuit wise, what do the three oddities actually do? The rest of the set seems conventional enough with normal looking frequency changer, IF, output and rectifier valves but then there's the three triodes...... are they detector, audio preamp and phase splitter or something more unusual? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O Last edited by Herald1360; 28th Oct 2012 at 6:12 pm.

2nd Nov 2012, 12:41 pm	#11
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: 2 top caps I managed to get to work on this chassis again Friday morning. The radio chassis now works! The three 2 top cap CV6 valves were in the audio stages, pre-amps and splitter. I managed to repair the one with no heaters by re-soldering/refitiing the valve base. Although the owner has supplied me with a new valve. There were 9 leaky capacitors to replace, all 0.1mfd expect for one at 0.05mfd, I think the builder of this radio had plenty of 0.1mfd's in stock. It still did not work, I injected an IF frequency to that stage and the IF was fine. Just the mixer/osc. to sort out. The valve used here is a VR99 and I found a wire hidden behind the wavechange switch going nowhere, after some circuit chasing I deducted where it should go and was rewarded with a lovely sounding radio. Long medium and short waves Apart from the valves above chassis, this radio also has a VR92 diode below chassis. It is working very well and I am surprised at how good it performs and sounds,- so I shall keep it for a few days and use it before giving it back to the owner!

2nd Nov 2012, 1:09 pm	#12
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: 2 top caps The knobs look very similar to CR100 type. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

2nd Nov 2012, 1:49 pm	#13
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: 2 top caps I agree about the knobs being like CR100 Hamish, apparently the owner of this home brew radio acquired it when he was purchasing an R1155 (of which he now has seven) so I think it was probably built by someone in the RAF, it may have been used in a Mess Hall or somewhere as it has a good push-pull audio output stage, and several speaker sockets. Plus gramophone pick up. It certainly has a punchy output. It is on at the moment. John