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 Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Reply
 
Thread Tools
Old 10th Mar 2021, 1:26 pm   #1
tony9191
Diode
 
Join Date: Mar 2021
Location: Plymouth, Devon, UK.
Posts: 6
Default R1155 power supply unit

I purchased on Ebay an R1155 radio , it came with a power unit :-
Serial Number 310 10K/946. This unit was used to test Spitfire Radios, the unit is fitted with Jones Plugs one six socket that fits the power unit, the other one has eight sockets which fits the radio. R11155 I tested the output of the unit it was 365 volts DC. I understand that the R1155 operates on up to 260 volts DC.
I have not plugged the radio into the supply, but I am confused, if the unit came with the radio the previous owner must have used it. The set was purchased from someone who found it in an attic.
Can someone offer advice please?
tony9191 is offline   Reply With Quote
Old 10th Mar 2021, 1:48 pm   #2
Keith
Heptode
 
Keith's Avatar
 
Join Date: Jan 2003
Location: Tewkesbury, Gloucestershire, UK.
Posts: 607
Default Re: R1155 power supply unit

Hi Tony,
If you measured the voltage without the R1155 connected the PSU would have been unloaded so the voltage would have risen above its normal level. That said, it still sounds excessive and possibly overstressing components within the receiver. You need to check it (carefully) with the receiver connected.
__________________
Keith Yates - G3XGW
VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm
Keith is offline   Reply With Quote
Old 12th Mar 2021, 11:53 am   #3
M0FYA Andy
Nonode
 
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,218
Default Re: R1155 power supply unit

The R1155 is designed to be operated on an HT supply of 220 volts, 260 volts is excessive, never mind 365 volts!

Andy
M0FYA Andy is offline   Reply With Quote
Old 12th Mar 2021, 1:09 pm   #4
Silicon
Octode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 1,355
Default Re: R1155 power supply unit

I would not connect that power supply to the R1155 until it was fully tested. It could burn out all the valve heaters! The chassis may be live.

Home made power supplies were often made to very poor standards by people with very little technical knowledge.

One possible reason for the high HT voltage could be that the mains transformer was designed for a different supply voltage.

Some sites may have used 110V AC for safety reasons. Mains supplies of 200V and 220V AC were common. Some were 25 or 40 Hz AC.

I would load the power supply by connecting high power resistors to the HT and heater outputs.
Measure the heater output voltage first. Power it up for a few seconds only.
Silicon is offline   Reply With Quote
Old 12th Mar 2021, 2:09 pm   #5
turretslug
Dekatron
 
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 3,743
Default Re: R1155 power supply unit

I can only concur with Silicon's comments- I've encountered some toe-curlingly horrible PSU lash-ups, including a Bendix RA-1B (similar HT voltage requirement to the R1155) run from a large 300-0-300 transformer with silicon rectifiers, a huge (ex-telly?) smoothing capacitor and whose standard of build on a slice of folded scrap steel sheet was so desperately dangerous that I'm stuck for polite words to describe it.

Depending on the circuit details, it is conceivable that the PSU in question could provide about the right voltage on-load- if it has a directly-heated thermionic rectifier with a relatively high forward drop and smoothing choke(s) with fairly high resistance, then 365V off-load could well drop to around 220V or so running, but a thorough examination/appraisal of the circuit and test with a representative load (that won't set things on fire if you go to answer the door or the phone!) is called for before you even think about connecting it to the receiver.
turretslug is offline   Reply With Quote
Old 12th Mar 2021, 2:59 pm   #6
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,932
Default Re: R1155 power supply unit

By the sound of that power supply, it was never meant for an 1155.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 13th Mar 2021, 8:14 am   #7
vosperd
Hexode
 
vosperd's Avatar
 
Join Date: Oct 2007
Location: Bristol, UK.
Posts: 380
Default Re: R1155 power supply unit

http://air-ministry.uk/airequip.htm

That psu is listed here as a ground psu for an TR1196.
The spec is there.
Don m5aky
vosperd is offline   Reply With Quote
Old 13th Mar 2021, 10:27 am   #8
Silicon
Octode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 1,355
Default Re: R1155 power supply unit

There is an air ministry power supply type 301 10K/946 which can provide 6.3V AC at 2.8 Amps and 230V DC at 70mA. It also gives 24-28V DC at 0.3A. I can't find a schematic.

The HT output may be 300V with no load. If the 24V supply is wired as a negative bias it may be possible to get 324V or more across two terminals.

Changes to the wiring, faulty components or a different rectifier valve could alter the output voltage.
Silicon is offline   Reply With Quote
Old 13th Mar 2021, 10:36 am   #9
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,932
Default Re: R1155 power supply unit

As I said, not designed or suitable in any way for an 1155.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 13th Mar 2021, 11:29 am   #10
Keith
Heptode
 
Keith's Avatar
 
Join Date: Jan 2003
Location: Tewkesbury, Gloucestershire, UK.
Posts: 607
Default Re: R1155 power supply unit

Quote:
Originally Posted by Silicon View Post
There is an air ministry power supply type 301 10K/946 which can provide 6.3V AC at 2.8 Amps and 230V DC at 70mA.

This is the PSU that the OP has. Sounds eminently suitable to me.
__________________
Keith Yates - G3XGW
VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm
Keith is offline   Reply With Quote
Old 13th Mar 2021, 11:56 am   #11
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,932
Default Re: R1155 power supply unit

I stand corrected, it threw me with the mention of that other receiver.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 18th Mar 2021, 11:59 am   #12
tony9191
Diode
 
Join Date: Mar 2021
Location: Plymouth, Devon, UK.
Posts: 6
Default Re: R1155 power supply unit

Thank you for your replies, I have since found one of these units on line with a picture. I notice that the picture shows a rectifier on the unit, my unit does not have the rectifier. If some one could give me some further advice on the rectifier and the connections, I would appreciate it.
tony9191 is offline   Reply With Quote
Old 18th Mar 2021, 5:08 pm   #13
vosperd
Hexode
 
vosperd's Avatar
 
Join Date: Oct 2007
Location: Bristol, UK.
Posts: 380
Default Re: R1155 power supply unit

The rectifier is probably for the 28V dc supply which is not required for the R1155.
It looks like the psu was a ground supply for the Spitfire radio, mentioned in your initial post, which would have been to hand.
One thing to remember is that the HT negative is not grounded in the power supply. As this psu has been used in the past with your 1155 it should be fine as long as there are no faults.
Don m5aky

Last edited by vosperd; 18th Mar 2021 at 5:14 pm.
vosperd is offline   Reply With Quote
Old 20th Mar 2021, 10:07 pm   #14
tony9191
Diode
 
Join Date: Mar 2021
Location: Plymouth, Devon, UK.
Posts: 6
Default Re: R1155 power supply unit

The main thing that concerns me is the high voltage, if the voltage was below 300 volts, I would consider connecting the power unit to the R1155.
Does anyone know the voltage drop across the set? The Spitfire radio operates on 275 volts DC, from checking the internet. I built the power supply plus amp from the schematic posted on the forum, but had an output of about 350 volts DC, so if that one was correct this one could also work.
tony9191 is offline   Reply With Quote
Old 21st Mar 2021, 10:36 am   #15
M0FYA Andy
Nonode
 
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,218
Default Re: R1155 power supply unit

As I commented earlier, the R1155 is designed to run with an HT of only 220v, anything higher will inevitably overstress the decoupling capacitors unless they have been replaced with higher-voltage types.

Andy
M0FYA Andy is offline   Reply With Quote
Old 21st Mar 2021, 10:40 am   #16
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 18,065
Default Re: R1155 power supply unit

Work out the current consumption of the R1155, then load up the PSU with wire wound resistors until that current flows. Measure the on load voltage and see how far it's dropped.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is offline   Reply With Quote
Old 21st Mar 2021, 12:55 pm   #17
turretslug
Dekatron
 
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 3,743
Default Re: R1155 power supply unit

There's the biassing circuit loss to take into account- I forget the value necessary for the R1155 but if it was, say, -30V, then that needs to be added to the optimum +220V HT to get the best-case 250V loaded overall output from a PSU- as Don (vosperd) points out, the HT- situation/connection in the PSU in question needs to be checked.

Colin
turretslug is offline   Reply With Quote
Old 21st Mar 2021, 1:04 pm   #18
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 10,853
Default Re: R1155 power supply unit

HT supply for the R1155 is 217 volts in the manual I have.

Lawrence.
ms660 is offline   Reply With Quote
Old 21st Mar 2021, 1:31 pm   #19
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,932
Default Re: R1155 power supply unit

I am confused as Silicon and Keith both say it is the correct supply , hence I got corrected when I said wrong one.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 21st Mar 2021, 2:33 pm   #20
vosperd
Hexode
 
vosperd's Avatar
 
Join Date: Oct 2007
Location: Bristol, UK.
Posts: 380
Default Re: R1155 power supply unit

As far as I know there is no "correct" power supply for the R1155 apart from the original ground supply for the 1154/1155 set up.
The main option is to make you own as most amateurs have done from what they had to hand.
As this set was used to test the TR 1196 I guess the guys in the workshop would have used what they had to hand. The spec of this psu is 230V at 70ma which is about right for the 1155 the odd 10V won't make much difference in my opinion.
The input of this psu is stated as 200 to 260V so there may be tappings that allow the voltage to be varied a bit. As it has a valve rectifier and a choke the voltage could easily drop down to about 230V under load.
I've seen the picture on the Mullard Magic site but there doesn't seem to be a circuit anywhere.
I wonder what arraangement was made fior the audio in this case.
Don m5aky
vosperd is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 5:50 am.


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 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.