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.

Reply
 
Thread Tools
Old 6th Aug 2022, 9:09 pm   #1
clockman
Pentode
 
Join Date: Jul 2020
Location: Borehamwood, Hertfordshire, UK.
Posts: 161
Default Pilot Little Maestro T105

Re the dial Bulb can i have help with the replacement of the 10 volt 0.2 Amp MES dial bulb as this is not now available can i use a different one with a resistor shunt as it needs to be quite bright maybe use a led one advice please TAB
clockman is offline   Reply With Quote
Old 8th Aug 2022, 9:51 am   #2
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,200
Default Re: Pilot Little Maestro T105

A common 12V 2.2W automotive instrument bulb could work OK.

The bulb current is actually a dirty mix of 100mA ac plus the dc HT current of the whole set, around 40mA so it shouldn't overload the 2.2W bulb.

Otherwise you could bung a 56R 3W resistor in the line, hang a small silicon bridge across it and experiment with LEDs and series resistors!
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline   Reply With Quote
Old 8th Aug 2022, 12:23 pm   #3
cathoderay57
Octode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 1,939
Default Re: Pilot Little Maestro T105

Well you can get qty 10 x 10v 0.2A here https://www.ebay.co.uk/itm/352161969726 and maybe offer the surplus to other T105 owners on the Forum? Alternatively, if that's too much money, then I would think you'd get away with this 12v 0.2A job without sacrificing too much brightness https://www.ebay.co.uk/itm/152993641737. Jerry
cathoderay57 is offline   Reply With Quote
Old 8th Aug 2022, 12:37 pm   #4
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 11,587
Default Re: Pilot Little Maestro T105

12V 2.2W LES bulbs are easily and cheaply available from the local car spares shop, I would try one. If it is too bright then a resistor in parallel will dim things a bit.
__________________
"The future's so bright I gotta wear shades". --Timbuk3
G6Tanuki is offline   Reply With Quote
Old 8th Aug 2022, 1:04 pm   #5
Sideband
Dekatron
 
Sideband's Avatar
 
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 6,884
Default Re: Pilot Little Maestro T105

Quote:
Originally Posted by cathoderay57 View Post
Well you can get qty 10 x 10v 0.2A here https://www.ebay.co.uk/itm/352161969726 and maybe offer the surplus to other T105 owners on the Forum?
I'd go for those! Just over 1 each sounds good to me and you can keep a spare and offer the rest on here if you want to. Might as well get the right lamp rather than faffing about trying to get the wrong type to work acceptably.
__________________
On Spike Milligan's headstone......I told you I was ill...
Sideband is offline   Reply With Quote
Old 8th Aug 2022, 2:02 pm   #6
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 4,962
Default Re: Pilot Little Maestro T105

I'm sure that a 12V 0.2A would be fine, though admittedly the pack of ten 10V 0.2A from Germany are the real deal, and with free P&P are good value.

If I'm reading the circuit correctly (someone will soon tell me if I'm not!), although not immediately obvious, the pilot bulb is in the series heater chain - at least in series with one side of the mains. Depending on how the mains plug is wired the bulb might be series with line or neutral. If the bulb fails, the radio will be dead.

The total voltage dropped by the hearer chain is 124V. (V1 19v, V2 17V, V3 50V, V4 38V). The heater current is 0.1A. The bulb is rated at 0.2A so will be underrun, which is no bad thing as it will prolong its life. I doubt that the 2V difference of either a 10 or 12V bulb will be noticeable, bearing in mind that the radio will be on the 240V mains tapping, and the mains will probably be a few volts below that.

Nice little radios.
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is offline   Reply With Quote
Old 8th Aug 2022, 2:17 pm   #7
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 12,431
Default Re: Pilot Little Maestro T105

Quote:
Originally Posted by David G4EBT View Post
The total voltage dropped by the hearer chain is 124V. (V1 19v, V2 17V, V3 50V, V4 38V). The heater current is 0.1A. The bulb is rated at 0.2A so will be underrun
According to the service sheet the DC load current is approx. 60mA so the current flowing through the lamp will be near 200mA.

Lawrence.
ms660 is offline   Reply With Quote
Old 8th Aug 2022, 3:26 pm   #8
clockman
Pentode
 
Join Date: Jul 2020
Location: Borehamwood, Hertfordshire, UK.
Posts: 161
Default Re: Pilot Little Maestro T105

I have taken the advice of Sideband and ordered 10 from Germany i will keep 5 so any one can have the rest for 1 each + post i also have 5 recovered metal rectifiers for free Ex Ultra Twin. TAB
clockman is offline   Reply With Quote
Old 8th Aug 2022, 3:38 pm   #9
clockman
Pentode
 
Join Date: Jul 2020
Location: Borehamwood, Hertfordshire, UK.
Posts: 161
Default Re: Pilot Little Maestro T105

They are a nice radio to work on very well made the service sheet is very basic not a lot of detail shows op valve as UCL82 uses a UCL83 print hard to read but hope to get my one working well.TAB
clockman is offline   Reply With Quote
Old 9th Aug 2022, 8:12 am   #10
Sideband
Dekatron
 
Sideband's Avatar
 
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 6,884
Default Re: Pilot Little Maestro T105

Later versions did use a UCL83 as a cost reduction exercise. I have had both versions (now sold on). I've never seen the later circuit with UCL83 so be aware that the valve pin connections are different. I think the scale lamp is described as a 'fuse bulb' so probably better to keep the correct type if possible.
__________________
On Spike Milligan's headstone......I told you I was ill...
Sideband is offline   Reply With Quote
Old 9th Aug 2022, 8:17 am   #11
Sideband
Dekatron
 
Sideband's Avatar
 
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 6,884
Default Re: Pilot Little Maestro T105

Quote:
Originally Posted by David G4EBT View Post
The heater current is 0.1A. The bulb is rated at 0.2A so will be underrun, which is no bad thing as it will prolong its life.
...plus the HT current which will add another 50 or so mA to the current so the bulb is probably running at around 150mA give or take.....
__________________
On Spike Milligan's headstone......I told you I was ill...
Sideband is offline   Reply With Quote
Old 9th Aug 2022, 8:47 am   #12
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 12,431
Default Re: Pilot Little Maestro T105

Quote:
Originally Posted by Sideband View Post
Quote:
Originally Posted by David G4EBT View Post
The heater current is 0.1A. The bulb is rated at 0.2A so will be underrun, which is no bad thing as it will prolong its life.
...plus the HT current which will add another 50 or so mA to the current so the bulb is probably running at around 150mA give or take.....
Plus the rest (reservoir capacitor charging current)

Lawrence.
ms660 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 4:48 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 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.