UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Closed Thread
 
Thread Tools
Old 19th Aug 2020, 5:15 pm   #1
kestrelmusic
Hexode
 
kestrelmusic's Avatar
 
Join Date: Feb 2008
Location: Wrexham, North Wales, UK.
Posts: 465
Default Yet another mystery valve!

I've just acquired a strange set - it's the basics of a Pye radiogram, with a (probably) home made amplifier tacked on inside.

The output valves are a pair of - what? They have a rope-and-anchor logo which suggests Navy tubes.

B7 base, 4 volt heaters. But the pinout is slightly odd:

1 - K?
2 - CG
3 - SG
4 - H
5 - H
6 - K
7 - NC
TC - A

The only valve I can find with this pinout is the AC6/Pen which is the same as NR74 or CV1189. However, this, according to RM, "a beam power amplifier designed for use with the output stage of a time base for magnetic TV scanning." Presumably they would work as audio output valves...? gm appears to be about 3mA/V.
Attached Thumbnails
Click image for larger version

Name:	Mystry (1).jpg
Views:	214
Size:	51.6 KB
ID:	213890   Click image for larger version

Name:	Mystry (2).jpg
Views:	180
Size:	54.9 KB
ID:	213891   Click image for larger version

Name:	Mystry (4).jpg
Views:	178
Size:	65.5 KB
ID:	213892   Click image for larger version

Name:	Mystry (3).jpg
Views:	171
Size:	53.8 KB
ID:	213893  
kestrelmusic is offline  
Old 19th Aug 2020, 5:20 pm   #2
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: Yet another mystery valve!

The rope-and-anchor looks rather US-styled - perhaps your amp is made using US-sourced valves (tubes) ??
G6Tanuki is offline  
Old 19th Aug 2020, 5:24 pm   #3
kestrelmusic
Hexode
 
kestrelmusic's Avatar
 
Join Date: Feb 2008
Location: Wrexham, North Wales, UK.
Posts: 465
Default Re: Yet another mystery valve!

Quote:
Originally Posted by G6Tanuki View Post
The rope-and-anchor looks rather US-styled - perhaps your amp is made using US-sourced valves (tubes) ??
It's a thought, but I don't think so because as far as I know no American valves were ever produced using B7 bases.
kestrelmusic is offline  
Old 19th Aug 2020, 5:45 pm   #4
turretslug
Dekatron
 
turretslug's Avatar
 
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
Default Re: Yet another mystery valve!

In pre-war TVs, there was still an expectation of a degree of linearity in timebase output valves (i.e. well before the TV22 etc. trend of the LOP valve acting as a switch), so it's entirely possible that someone thought of using them as audio power valves. Maybe the "navy" logo suggests that an existing valve with good cathode current capability was taken on board (metaphorically and literally) for modulator (linear or pulse), RF PA, series regulator, whatever use and there were a goodly load surplus post-war.

Just thinking aloud!
turretslug is offline  
Old 19th Aug 2020, 6:01 pm   #5
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: Yet another mystery valve!

Could just be Anchor brand, not necessarily Navy?
AC/HL is offline  
Old 19th Aug 2020, 6:22 pm   #6
barrymagrec
Octode
 
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,552
Default Re: Yet another mystery valve!

Kt44?
barrymagrec is offline  
Old 19th Aug 2020, 6:44 pm   #7
Freya
Octode
 
Freya's Avatar
 
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,987
Default Re: Yet another mystery valve!

Its depicting the foul anchor in its British form.
The U.S. navy later used it and added USN Unity Service Navigation

All i can remember from sea cadets.... many years ago
__________________
Stephen
_________"It`s only an old telly" ___
Freya is offline  
Old 19th Aug 2020, 6:52 pm   #8
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: Yet another mystery valve!

Base aside, it looks similar to this PEN46:

http://www.r-type.org/exhib/aaa0137.htm

Lawrence.
ms660 is offline  
Old 19th Aug 2020, 10:02 pm   #9
Wellington
Hexode
 
Wellington's Avatar
 
Join Date: Jun 2009
Location: Cheshire, UK.
Posts: 363
Question Re: Yet another mystery valve!

Did the EL32 have a B7 version? (Though even as I mention that, I can see that your valve looks meatier).
Wellington is offline  
Old 19th Aug 2020, 10:46 pm   #10
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
Default Re: Yet another mystery valve!

Quote:
Originally Posted by ms660 View Post
Base aside, it looks similar to this PEN46:

http://www.r-type.org/exhib/aaa0137.htm

Lawrence.

Apart from the base and a couple of very minor differences, the datsheets from Mazda look identical.


A p-p pair should be good for 20W+.
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline  
Old 19th Aug 2020, 11:00 pm   #11
m0cemdave
Octode
 
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,205
Default Re: Yet another mystery valve!

I'd say it's an AC6/PEN - or the Navy version, NR74.
m0cemdave is offline  
Old 20th Aug 2020, 12:10 am   #12
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: Yet another mystery valve!

I would agree with Lawrence, there are some Mazda AC6/PEN on ebay https://www.ebay.co.uk/itm/Quad-4-Ma...AAAOSwZoVeSxxb
PJL is offline  
Old 20th Aug 2020, 9:21 am   #13
Catkins
Pentode
 
Catkins's Avatar
 
Join Date: Feb 2015
Location: Chepstow, Monmouthshire, UK.
Posts: 234
Default Re: Yet another mystery valve!

I have a small collection of different AC6/PENs.

Looking at the pictures, I would say it is definitely a late 40s/50s AC6/PEN, or the same date NR74, as they're identical. Pre-war production AC6/PENs had different holes on the anode.

Photo 1 shows on the left a late 40s/50s AC6/PEN with a pre-war AC6/PEN on the right.

Photo 2 shows the same valves viewed from the top.

Photo 3 shows the later AC6/PEN with a British military NR74. They are identical.

Photo 4 shows an American Raytheon NR74. As you should see the construction is very different.

The AC6/PEN was used in pre-war televisions, and was a more powerful version of the AC5/PEN. In the Murphy A56V television of 1938, the AC5/PEN was used as the audio output valve, and the frame timebase output valve. The AC6/PEN was used as the line timebase output valve where more power is needed. I see no reason why it couldn't have been used as an audio output valve.
Attached Thumbnails
Click image for larger version

Name:	IMG_3887.jpg
Views:	58
Size:	57.1 KB
ID:	213928   Click image for larger version

Name:	IMG_3889.jpg
Views:	57
Size:	71.1 KB
ID:	213929   Click image for larger version

Name:	IMG_3890.jpg
Views:	67
Size:	50.5 KB
ID:	213930   Click image for larger version

Name:	IMG_3892.jpg
Views:	57
Size:	49.5 KB
ID:	213931  
Catkins is offline  
Old 20th Aug 2020, 9:58 am   #14
Catkins
Pentode
 
Catkins's Avatar
 
Join Date: Feb 2015
Location: Chepstow, Monmouthshire, UK.
Posts: 234
Default Re: Yet another mystery valve!

I forgot to mention, the reason why the anode is brought out to a top-cap, and kept separate from the other pins (unlike the AC5/PEN), is due to large back emf voltages when used as a line timebase output valve. During line scan flyback, large emf voltages flow back from the deflection coil, of about 2,000 volts, and the valve has to be able to handle that.
Catkins is offline  
Old 20th Aug 2020, 9:59 am   #15
Gridiron
Heptode
 
Join Date: Apr 2010
Location: West Midlands, UK.
Posts: 659
Default Re: Yet another mystery valve!

Isn't the PEN46 basically the same valve as the AC6/PEN updated with a Mazda Octal base.
Gridiron is offline  
Old 20th Aug 2020, 10:01 am   #16
Catkins
Pentode
 
Catkins's Avatar
 
Join Date: Feb 2015
Location: Chepstow, Monmouthshire, UK.
Posts: 234
Default Re: Yet another mystery valve!

Quote:
Originally Posted by Gridiron View Post
Isn't the PEN46 basically the same valve as the AC6/PEN updated with a Mazda Octal base.
Yes, and it was used in post-war televisions, e.g. the Murphy V114 of 1946.

Similarly, the AC5/PEN updated with a Mazda Octal base became the very widely used PEN45.
Catkins is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 2:22 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.