HT Transformer - UK Vintage Radio Repair and Restoration Discussion Forum

Malcolm G6ANZ · 9th Jul 2023, 9:31 am

I have to make an HT supply for the R103. Originally it used a vibrator so it could run from a 12v car battery but I will power it from a dedicated mains supply. I require a transformer to supply 200v at 70mA and 6.3v at 4A. does anyone have such a beast?
Also the audio output valve was missing so I need a 6V6G.

Malcolm

Radio Wrangler · 9th Jul 2023, 9:37 am

If there's space for a 6V6G, then it ought to be able to use 6V6GT in the straight bottle as well as a plain 6V6 in the metal bottle. This may open your options a little.

If there's none near you, I think I have a few spare 6V6GT and could spare one.

David

Ed_Dinning · 9th Jul 2023, 10:49 am

Hi Malcolm, 6.3 V at 4A is a bit high for a 70mA HT transformer, do you have the space for a separate heater transformer?

Ed

CambridgeWorks · 9th Jul 2023, 11:22 am

Malcom, 4A seems heck of a lot for the valve heaters. Is that a mistake?
Can you list the valves it uses? Add up the current of all of them.
Are you assuming the 70mA ht is correct just because that is the absolute maximum the rectifier (whatever it is) can supply?
Rob

Malcolm G6ANZ · 9th Jul 2023, 12:04 pm

The heater current was an error. I misread the current on the data sheet. It specifies 4.5A @ 12v supply, further down it states that LT is 2.5A. and the HT is 72mA at 200v
The valves are VR65, VR99 4off 6B8G and a 6V6
The heater currents
VR 65 0.6A
6K8G 0.3A
6B8G 0.3A (4 of)
6V6 0.45A

2.55A So 3A winding should be more than enough 2.5A may well work OK

Malcolm

CambridgeWorks · 9th Jul 2023, 3:30 pm

Thats more like it!
Sorry, I have nothing suitable though. There was a thread recently about a R1155 psu, which should be 220v ht.
I don't know what the outcome was though.
Rob

Edit:
https://www.vintage-radio.net/forum/...d.php?t=200966

Jez1234 · 9th Jul 2023, 5:16 pm

The HT transformer I recently needed turned out so unobtainium that I've designed a SMPS to do the job... still a WIP... only around 30 hours and £40 spent on it so far to get round paying maybe £120 for a one off to be made

9th Jul 2023, 9:31 am	#1
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,042	HT Transformer I have to make an HT supply for the R103. Originally it used a vibrator so it could run from a 12v car battery but I will power it from a dedicated mains supply. I require a transformer to supply 200v at 70mA and 6.3v at 4A. does anyone have such a beast? Also the audio output valve was missing so I need a 6V6G. Malcolm

9th Jul 2023, 9:37 am	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,915	Re: HT Transformer If there's space for a 6V6G, then it ought to be able to use 6V6GT in the straight bottle as well as a plain 6V6 in the metal bottle. This may open your options a little. If there's none near you, I think I have a few spare 6V6GT and could spare one. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

9th Jul 2023, 10:49 am	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,196	Re: HT Transformer Hi Malcolm, 6.3 V at 4A is a bit high for a 70mA HT transformer, do you have the space for a separate heater transformer? Ed

9th Jul 2023, 11:22 am	#4
CambridgeWorks Nonode Join Date: Jun 2010 Location: Spalding, Peterborough, Cambridgeshire, UK. Posts: 2,859	Re: HT Transformer Malcom, 4A seems heck of a lot for the valve heaters. Is that a mistake? Can you list the valves it uses? Add up the current of all of them. Are you assuming the 70mA ht is correct just because that is the absolute maximum the rectifier (whatever it is) can supply? Rob __________________ Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd

9th Jul 2023, 12:04 pm	#5
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,042	Re: HT Transformer The heater current was an error. I misread the current on the data sheet. It specifies 4.5A @ 12v supply, further down it states that LT is 2.5A. and the HT is 72mA at 200v The valves are VR65, VR99 4off 6B8G and a 6V6 The heater currents VR 65 0.6A 6K8G 0.3A 6B8G 0.3A (4 of) 6V6 0.45A 2.55A So 3A winding should be more than enough 2.5A may well work OK Malcolm

9th Jul 2023, 3:30 pm	#6
CambridgeWorks Nonode Join Date: Jun 2010 Location: Spalding, Peterborough, Cambridgeshire, UK. Posts: 2,859	Re: HT Transformer Thats more like it! Sorry, I have nothing suitable though. There was a thread recently about a R1155 psu, which should be 220v ht. I don't know what the outcome was though. Rob Edit: https://www.vintage-radio.net/forum/...d.php?t=200966 __________________ Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd Last edited by CambridgeWorks; 9th Jul 2023 at 3:36 pm. Reason: Added link

9th Jul 2023, 5:16 pm	#7
Jez1234 Banned Join Date: Mar 2021 Location: Morpeth, Northumberland, UK. Posts: 936	Re: HT Transformer The HT transformer I recently needed turned out so unobtainium that I've designed a SMPS to do the job... still a WIP... only around 30 hours and £40 spent on it so far to get round paying maybe £120 for a one off to be made