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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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Old 21st Mar 2021, 3:03 pm   #21
M0FYA Andy
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Default Re: R1155 power supply unit

Quote:
Originally Posted by turretslug View Post
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
The voltage dropped in the biasing circuit isn't in addition to the 220 volts. The HT negative sits 'below' chassis ground at the biasing voltage and the HT positive sits at 220 volts above HT negative. So HT positive is at (220v - bias) above chassis. There is no -30v output from the ground PSU.

Andy
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Old 21st Mar 2021, 9:17 pm   #22
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Default Re: R1155 power supply unit

I think that the power supply has the 'potential' to be suitable for the R1155.

It may be necessary to convert it to a 'choke input' type of power supply to reduce the output DC voltage. The original circuit was probably a 'CLC' type.

Changing from the original valve to a solid state rectifier will give more output voltage options.
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Old 26th Mar 2021, 10:00 pm   #23
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Default Re: R1155 power supply unit

I would find out what the normal load current would be for a working receiver then work out a load resistor and put that across your PSU and measure the output voltage.
If it's still high the make some changes to it before running your radio from it.
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Old 26th Mar 2021, 10:53 pm   #24
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Default Re: R1155 power supply unit

I found this a moment ago,Les
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Old 16th Apr 2021, 5:17 pm   #25
tony9191
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Default Re: R1155 power supply unit

I would to thank every one for their replies. I have decided not to use the PSU in question. My friend helped me construct a PSU with AMP from one of the schematics on the forum. The PSU has been completed, but the output voltage is 280 Volts DC. We followed the circuit to the letter and have rechecked everything, but still get 280 Volts DC.

What can the problem be, or is it safe to connect the R1155?
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Old 16th Apr 2021, 7:02 pm   #26
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Default Re: R1155 power supply unit

Is that on load or off load voltage?

A circuit for the PSU or a link to the thread concerned would be useful.
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Old 17th Apr 2021, 10:34 am   #27
tony9191
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Default Re: R1155 power supply unit

The voltage is off load, the circuit diagram in question is the one discussed on 3rd December 2018 , with a question about a connection on pin 5 sharing two wires.
Attached is a thumbnail of the circuit, on the same date is the reply from a member correcting the connection where the wire be connected to.
I hope this helps
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Old 17th Apr 2021, 12:17 pm   #28
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Default Re: R1155 power supply unit

This thread presumably?

https://www.vintage-radio.net/forum/...d.php?t=152000

The HT supply is unregulated, so the voltage will drop on load.
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Old 17th Apr 2021, 4:42 pm   #29
tony9191
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Default Re: R1155 power supply unit

Thank you for your reply, my dad had one of these radios in the 1960's and he purchased a power supply and amp from a company called Laskeys, it was housed in a tin box will a lead complete with a Jones Plug. he plugged it into the R1155 and it worked perfectly. At the time he never thought of checking the voltage, so when I purchased mine and completed the PSU in Question, I was concerned with high voltage, that I had.
So thank you for putting my mind at ease, and thank you also to all members who took part. I will still monitor this site, it is so informative.
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Old 9th May 2021, 6:32 am   #30
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Default Re: R1155 power supply unit

In such a situation I would use a Variac (Variable Voltage Transformer) and meter the HT while slowly bringing up the mains voltage from about half normal. You may find that the voltage when loaded doesn't go above the specified level. You would want to increase the input voltage slowly, to give the heaters time to get the valves drawing current. A light dimmer that uses a triac (rather than a thyristor) can be used as a poor man's variac in most cases. Be careful with those Jones Plugs, the cases can become live if not earthed. Better not to touch the metal cases.
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