KB 'Pup' - AC version. General interest info. - UK Vintage Radio Repair and Restoration Discussion Forum

FRANK.C · 31st May 2006, 6:40 pm

Hi All
I got this radio recently. I am trying to identify it. I assume that it is a KB as it got KB stamped on its back.

I have got all of Paul's CDs but I cant find anything there like it. Its a 2 valve plus rectifier mains set. The valve line-up is AC/HL, AC/P and 506K. Does anyone know where I can get Service Data for it?

Regards,
Frank.

jim_beacon · 31st May 2006, 6:49 pm

Hi Frank,

it looks like the AC version of the KB "Pup" - more often seen in the sloping side cabinet.

Jim.

Ed_Dinning · 31st May 2006, 9:22 pm

Hi Frank, I would be interested in any pics you take, I have restored 2, battery pups, but never a mains one.
I have the paxolin chassis for the mains one but no idea of the speaker or PSU and where it was located.
Many thanks, Ed

jim_beacon · 31st May 2006, 9:26 pm

Hi Ed,

I can take some pictures of mine, but I'm missing the original speaker.

Jim.

FRANK.C · 31st May 2006, 11:50 pm

Hi Ed
My one is in a sorry state. It's in bits!. But Most of it is there. The PSU appears to be complete. The speaker is there but at some stage it had a crash with the PSU (The PSU was not bolted down when I got it) the cone is damaged and the metal support that holds the reed is broken. I think there should be some sort of a switch on the top of the Cabinet but that is missing. When you look from the front the right hand side has got two holes in it I can only guess that they may be for Aerial and Earth Terminals?. The paxolin chassis is there but it has been got at there are components hanging of it. The Valves are all there I haven't checked them yet. I will try and take some photos of it tomorrow and post them at least when its in bits it will be easier to take them.

The PSU is built on a Wooden Chassis and bolted to the bottom of the Cabinet

Just remembered I took a couple of pic's before

Regards
Frank

Ed_Dinning · 1st Jun 2006, 12:35 pm

Hi Frank & Jim. Pics would be helpful. The battery sets I've worked on had B4 or B5 valve holdes as part of the paxolin, but the B%'s had no centre pin.
The mains chassis I have has B5's with a centre pin. The baseboard mounting valveholder looks like an addition; I believed that the rectifier was part of the power pack.
The switch on the mains and battery sets (On-Off) was a crude brass strip that switched the filaments and was part of the "chassis". It stuck up through a slot in the cabinet.
Circuitry was very simple with a single tuning coil and reaction. The solid dielectric caps are often damaged by being forced too far round, breaking the stop - it can be fixed with a solder tag.
The local/distant and MW/LW switching is accomplished with a wanger plug on the paxolin aerial panel, which from memory had 5 sockets. this should be clearer when you see Jim's drawings.
There is also a single intervalve transformer.
The last one I repaired eemed to run OK considering its simple design. I built a small mains unit of my own design to fit inside the case.

HTH Ed

FRANK.C · 1st Jun 2006, 7:58 pm

Hi Jim and Ed
I have took some new photos and posted them. If there is any particular photo you would like please let me know. I don't believe the mains transformer is original as there are different fixing holes which were used in the past. If any one has a photo which includes the switch on the top of the radio I would love to see it as the switch is missing on mine. I was looking at the reed speaker today (I haven't seen a reed speaker before) and noticed that the poles were magnetised I assume that this is from DC passing through the speaker. Would it benefit if it were demagnetised?.

Regards
Frank

Ed_Dinning · 4th Jun 2006, 8:34 pm

Hi Gents sorry for the delay as it's been a hectic weekend.
I will hopefully attach some pics of my mauins Pup chassis. It looks as though yours has been modified for plug in coils, mine were fixed on both versions.
In an early form of PCB they adopted the modern technique of having both the chassis and the aerial input panel on one plate, then smapping them when built. The switch on mine is a brass arm (20 thou) that moves under a clip on the chassis. This is another piece of brass, rather like the contact on a wafer switch.
On re-examination of my mains version I see it does not have the LT switch the way the battery one did. The illustrations in the BVWS bull show a speaker switch on the side of the cabinet, but I'm not sure if this was correct as it may have been a mains switch for the mains version.

I'd be very interested in any further sketches or pics of the mains version and it's power pack. PM me with you address and I'll send copies of the data I have. It appears that there were several similar sets in the range with very similar circuitry.

Hi Gents, files are over 1M so too big, PM me your e-mails and I'll send them on.

Best regards, Ed

FRANK.C · 27th Jun 2006, 11:32 pm

Update on Pup

After checking the power supply section the two smoothing caps were changed all else was OK expect for the resistor in series with the smoothing choke was found to be open, there was no value marked on it but a suitable value was worked out . I replaced it with a modern wirewound, the original was a cylindrical dropper type, I carefully removed the ceramic casing from the replacement and I then could fit it inside the original keeping the appearance. The no load voltage was found to be 370V which was uncomfortably high as there was 400V caps fitted. The Mains Transformer was not original so I connected two sets of three 27V 1.2 watt Zener Diodes in series and put them in the anode circuit of the rectifier. I was able to cover them with sleeving so they cant be seen. This brought down the no load voltage to 290V. This allowed to change the value of the series resistor that I had replaced from 12K to 2K7.

The reed speaker was badly damaged. The cone was ripped and the support for the reeth was broken in two. After gluing all back together it worked OK.

The main chassis was pretty much intact I just had to replace the 50uF cap in cathode of the output valve and replaced some wiring that was falling apart.

The loose veneer was glued back onto the cabinet and the split side panel was glued back together. The finish was flaking so I striped it and Refinished with Teak Oil.

After putting all back together the radio performs very well for a two valver. The transmitter for RTE radio 1 on 252 kHz Long wave is about 50 to 60 miles away from me, and can be received with fair volume by touching the aerial terminal with a finger and without any earth.

I have drawn the circuit of the working radio without the mods. If anyone wishes to have a copy please PM me and I will forward.

A BIG thanks to Jim and Ed, for without there help I would not have been able to achieved this.

Regards
Frank

31st May 2006, 6:40 pm	#1
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	KB 'Pup' - AC version. General interest info. Hi All I got this radio recently. I am trying to identify it. I assume that it is a KB as it got KB stamped on its back. I have got all of Paul's CDs but I cant find anything there like it. Its a 2 valve plus rectifier mains set. The valve line-up is AC/HL, AC/P and 506K. Does anyone know where I can get Service Data for it? Regards, Frank. Attached Thumbnails Last edited by Darren-UK; 16th Sep 2007 at 1:47 pm. Reason: General tidying.

31st May 2006, 6:49 pm	#2
jim_beacon Retired Dormant Member Join Date: Mar 2003 Location: Bishop's Waltham, Hants, UK. Posts: 939	Re: Can you identify this KB? Hi Frank, it looks like the AC version of the KB "Pup" - more often seen in the sloping side cabinet. Jim. Last edited by Darren-UK; 16th Sep 2007 at 1:43 pm. Reason: PM/email arrangements removed.

31st May 2006, 9:22 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Can you identify this KB? Hi Frank, I would be interested in any pics you take, I have restored 2, battery pups, but never a mains one. I have the paxolin chassis for the mains one but no idea of the speaker or PSU and where it was located. Many thanks, Ed

31st May 2006, 9:26 pm	#4
jim_beacon Retired Dormant Member Join Date: Mar 2003 Location: Bishop's Waltham, Hants, UK. Posts: 939	Re: Can you identify this KB? Hi Ed, I can take some pictures of mine, but I'm missing the original speaker. Jim.

31st May 2006, 11:50 pm	#5
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: Can you identify this KB? Hi Ed My one is in a sorry state. It's in bits!. But Most of it is there. The PSU appears to be complete. The speaker is there but at some stage it had a crash with the PSU (The PSU was not bolted down when I got it) the cone is damaged and the metal support that holds the reed is broken. I think there should be some sort of a switch on the top of the Cabinet but that is missing. When you look from the front the right hand side has got two holes in it I can only guess that they may be for Aerial and Earth Terminals?. The paxolin chassis is there but it has been got at there are components hanging of it. The Valves are all there I haven't checked them yet. I will try and take some photos of it tomorrow and post them at least when its in bits it will be easier to take them. The PSU is built on a Wooden Chassis and bolted to the bottom of the Cabinet Just remembered I took a couple of pic's before Regards Frank Attached Thumbnails

1st Jun 2006, 12:35 pm	#6
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Can you identify this KB? Hi Frank & Jim. Pics would be helpful. The battery sets I've worked on had B4 or B5 valve holdes as part of the paxolin, but the B%'s had no centre pin. The mains chassis I have has B5's with a centre pin. The baseboard mounting valveholder looks like an addition; I believed that the rectifier was part of the power pack. The switch on the mains and battery sets (On-Off) was a crude brass strip that switched the filaments and was part of the "chassis". It stuck up through a slot in the cabinet. Circuitry was very simple with a single tuning coil and reaction. The solid dielectric caps are often damaged by being forced too far round, breaking the stop - it can be fixed with a solder tag. The local/distant and MW/LW switching is accomplished with a wanger plug on the paxolin aerial panel, which from memory had 5 sockets. this should be clearer when you see Jim's drawings. There is also a single intervalve transformer. The last one I repaired eemed to run OK considering its simple design. I built a small mains unit of my own design to fit inside the case. HTH Ed

1st Jun 2006, 7:58 pm	#7
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: Can you identify this KB? Hi Jim and Ed I have took some new photos and posted them. If there is any particular photo you would like please let me know. I don't believe the mains transformer is original as there are different fixing holes which were used in the past. If any one has a photo which includes the switch on the top of the radio I would love to see it as the switch is missing on mine. I was looking at the reed speaker today (I haven't seen a reed speaker before) and noticed that the poles were magnetised I assume that this is from DC passing through the speaker. Would it benefit if it were demagnetised?. Regards Frank Attached Thumbnails

4th Jun 2006, 8:34 pm	#8
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Can you identify this KB? Hi Gents sorry for the delay as it's been a hectic weekend. I will hopefully attach some pics of my mauins Pup chassis. It looks as though yours has been modified for plug in coils, mine were fixed on both versions. In an early form of PCB they adopted the modern technique of having both the chassis and the aerial input panel on one plate, then smapping them when built. The switch on mine is a brass arm (20 thou) that moves under a clip on the chassis. This is another piece of brass, rather like the contact on a wafer switch. On re-examination of my mains version I see it does not have the LT switch the way the battery one did. The illustrations in the BVWS bull show a speaker switch on the side of the cabinet, but I'm not sure if this was correct as it may have been a mains switch for the mains version. I'd be very interested in any further sketches or pics of the mains version and it's power pack. PM me with you address and I'll send copies of the data I have. It appears that there were several similar sets in the range with very similar circuitry. Hi Gents, files are over 1M so too big, PM me your e-mails and I'll send them on. Best regards, Ed

27th Jun 2006, 11:32 pm	#9
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: Can you identify this KB? Update on Pup After checking the power supply section the two smoothing caps were changed all else was OK expect for the resistor in series with the smoothing choke was found to be open, there was no value marked on it but a suitable value was worked out . I replaced it with a modern wirewound, the original was a cylindrical dropper type, I carefully removed the ceramic casing from the replacement and I then could fit it inside the original keeping the appearance. The no load voltage was found to be 370V which was uncomfortably high as there was 400V caps fitted. The Mains Transformer was not original so I connected two sets of three 27V 1.2 watt Zener Diodes in series and put them in the anode circuit of the rectifier. I was able to cover them with sleeving so they cant be seen. This brought down the no load voltage to 290V. This allowed to change the value of the series resistor that I had replaced from 12K to 2K7. The reed speaker was badly damaged. The cone was ripped and the support for the reeth was broken in two. After gluing all back together it worked OK. The main chassis was pretty much intact I just had to replace the 50uF cap in cathode of the output valve and replaced some wiring that was falling apart. The loose veneer was glued back onto the cabinet and the split side panel was glued back together. The finish was flaking so I striped it and Refinished with Teak Oil. After putting all back together the radio performs very well for a two valver. The transmitter for RTE radio 1 on 252 kHz Long wave is about 50 to 60 miles away from me, and can be received with fair volume by touching the aerial terminal with a finger and without any earth. I have drawn the circuit of the working radio without the mods. If anyone wishes to have a copy please PM me and I will forward. A BIG thanks to Jim and Ed, for without there help I would not have been able to achieved this. Regards Frank Attached Thumbnails