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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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9th Sep 2020, 9:14 pm | #1 |
Diode
Join Date: Sep 2020
Location: Kingston upon Thames, London, UK.
Posts: 6
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R1155 Resistor wattage?
Whilst I have a list of R values required to replace many of the resisters in an old R1155 ( which all seem to be miles out) I cannot find any data to tell me the wattage required...and I find it hard to calculate as some power supplies seem to be at 270v Ht+ to Ht- whilst others seem to be much lower .... .If I take the screen grids for instance...they say they should be approx 60-80 volts.... mine are nearer to 110 V ....and the screen resister network works out that I need resisters of over 1 watt.....ie.. 240 volt Ht to earth , 23K and 27K in series for screen voltage .
Is there a rule of thumb for wattage for all the resisters ( other than R1) or is there a list some where.... |
9th Sep 2020, 9:32 pm | #2 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,510
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Re: R1155 Resistor wattage?
Are you replacing them with modern resistors? If so, just use 2 watt or greater types as they will then also be physically large enough to look 'at home'.
Andy |
9th Sep 2020, 11:33 pm | #3 |
Diode
Join Date: Sep 2020
Location: Kingston upon Thames, London, UK.
Posts: 6
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Re: R1155 Resistor wattage?
Yes ... Modern metal film I guess..... so 2 watt will be good for all...thanks
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10th Sep 2020, 8:51 am | #4 |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,498
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Re: R1155 Resistor wattage?
Worth doing in any case - the disspation in resistors fitted to valve equipment can be surprisingly high. It is easy to forget this after working extensively on low-voltage, low current semiconductor stuff!
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10th Sep 2020, 9:08 am | #5 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,851
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Re: R1155 Resistor wattage?
Quote OP : .and I find it hard to calculate as some power supplies seem to be at 270v Ht+ to Ht- whilst others seem to be much lower ....
I thought the R1155 was around 210V ht? Rob
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10th Sep 2020, 10:18 am | #6 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
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Re: R1155 Resistor wattage?
Think you are right ,around 210V.
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