A couple of sad valves... - UK Vintage Radio Repair and Restoration Discussion Forum

G6Tanuki · 4th May 2019, 2:53 pm

A friend was clearing out a shed that's been in his family since the mid-1940s and came across a couple of valves which he gave to me, having no interest in such things himself.

Both are on the old "British" base, one is a 5-pin triode the other has 7 pins and a top-cap.

The triode's got no obvious markings, but it's indirectly-heated. Other is a Mazda and the code "V45" is visible but the last digit has been lost as the metallising has flaked-off through decades of damp.

I'm thinking it is probaly a V455 - http://www.r-type.org/exhib/aaa1069.htm

Next thing is to reach for my variable-voltage supply and see what lights up. But then - what to do with them? I've got a Cossor "42OT" output-valve here somewhere - maybe I pair the V455 with it and make a 'classic' single-ended 2-valve amp? Alas, 4-volt heater/HT transformers are not easy to come by.

ValvoStef · 4th May 2019, 3:09 pm

You could buy a 5V toroidal and take some turns off, or heat them with 4V dc.

G6Tanuki · 4th May 2019, 3:24 pm

I'm thinking a classic mains-transformer with a 5V winding intended for a directly-heated rectifier, used with a beefy wirewound resistor.

Ed_Dinning · 4th May 2019, 8:10 pm

Hi Tanuki, I still have a few of the 4v +4v +250-0-250 transformers around, yours for the postage if you want to give it a try.

Ed

turretslug · 4th May 2019, 8:53 pm

Always worth keeping the eyes peeled for 'eclipsed projects' amongst the rummage boxes at rallies- the RS general purpose HT transformers and others quite often have a 4V tapping on heater windings, presumably there was a significant replacement demand for the likes of British pre-war sets.

Biggles · 5th May 2019, 6:27 pm

From the photo it's obvious that these valves are gigantic and I suspect that whatever you decide to build with them will be impractically large.
Alan.

Herald1360 · 6th May 2019, 8:05 pm

6.3V and six cheap silicon diodes?

G6Tanuki · 8th May 2019, 1:17 pm

Quote:

Originally Posted by Herald1360

6.3V and six cheap silicon diodes?

Now that's an idea - I've got a few old 'bolt-down' bridge-rectifiers where one diode has failed; each package can still be coerced into providing at least two series-connected diodes though.

4th May 2019, 2:53 pm	#1
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,005	A couple of sad valves... A friend was clearing out a shed that's been in his family since the mid-1940s and came across a couple of valves which he gave to me, having no interest in such things himself. Both are on the old "British" base, one is a 5-pin triode the other has 7 pins and a top-cap. The triode's got no obvious markings, but it's indirectly-heated. Other is a Mazda and the code "V45" is visible but the last digit has been lost as the metallising has flaked-off through decades of damp. I'm thinking it is probaly a V455 - http://www.r-type.org/exhib/aaa1069.htm Next thing is to reach for my variable-voltage supply and see what lights up. But then - what to do with them? I've got a Cossor "42OT" output-valve here somewhere - maybe I pair the V455 with it and make a 'classic' single-ended 2-valve amp? Alas, 4-volt heater/HT transformers are not easy to come by. Attached Thumbnails

4th May 2019, 3:09 pm	#2
ValvoStef Hexode Join Date: Mar 2014 Location: Fareham, Hampshire, UK. Posts: 482	Re: A couple of sad valves... You could buy a 5V toroidal and take some turns off, or heat them with 4V dc. __________________ Failing to prepare is preparing to fail ...

4th May 2019, 3:24 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,005	Re: A couple of sad valves... I'm thinking a classic mains-transformer with a 5V winding intended for a directly-heated rectifier, used with a beefy wirewound resistor.

4th May 2019, 8:10 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: A couple of sad valves... Hi Tanuki, I still have a few of the 4v +4v +250-0-250 transformers around, yours for the postage if you want to give it a try. Ed

4th May 2019, 8:53 pm	#5
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,398	Re: A couple of sad valves... Always worth keeping the eyes peeled for 'eclipsed projects' amongst the rummage boxes at rallies- the RS general purpose HT transformers and others quite often have a 4V tapping on heater windings, presumably there was a significant replacement demand for the likes of British pre-war sets.

5th May 2019, 6:27 pm	#6
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: A couple of sad valves... From the photo it's obvious that these valves are gigantic and I suspect that whatever you decide to build with them will be impractically large. Alan.

6th May 2019, 8:05 pm	#7
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: A couple of sad valves... 6.3V and six cheap silicon diodes? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O