ulc82

[Danndad]

My new polish telam ucl82 has a heater resistance of 80r (cold) and when in use I am getting a reading of nearly 55vac, on the pins, valve data says they should be 50vac.
My old mallard ucl82 when installed, the heater voltage was 50vac and its heater resistance when cold was around 71r
Can I run my new telam valve with that extra 5v increase safely, I take it the extra voltage is due to the higher heater resistance. All the other valves in the chain are all fine with regards to the heater voltages.

Danndad

[boater sam]

Its within 10%, just, which I would consider to be OK.
Series chains are less critical as over/under voltage is shared across the chain.

[ppppenguin]

Cold resistance doesn't matter. That only affects the surge current at start of warm-up. What really matters is the current. It should be 100mA for U series valves. If you have a meter that can measure AC current you can break the heater chain and make the measurement.

[Danndad]

Thanks for the prompt replies.
I’d not heard of telam valves before so I had a quick google and couldn’t find anything sinister regarding them so I ordered a pair, they both have high heater resistances, is this because they are cheap?
I  did manage to get into the heater chain and after a high initial start at switch on , the current settled very quickly and stayed a steady 98.8ma.

Danndad

[ppppenguin]

I wouldn't be concerned about this fairly small difference in cold heater resistance. Possibly they are being made to looser tolerances than the Mullard originals but if they work OK there's no need to worry.

[Murphyv310]

Your Polish set is 220v AC most likely and our mains is nominally 230v and usually 235-240v so this is where your increased heater volts is coming from. Add a suitable 5 watt resistor in series with the heater chain of 150 ohms.

[ppppenguin]

Trevor, not sure about your diagnosis. The OP has measured the heater current at almost spot on 100mA. Assuming the measurements are accurate, the UCL82 really is running at 55V and 100mA.

[Murphyv310]

I'd question that TBH. All Polish sets that I've come across are 220v although there could be exceptions, perhaps the OP could let us know if it's got a 240v tapping.

[Crackle]

It should all be OK if the series current is 100mA or less.

Mike

[ppppenguin]

Your Polish set is 220v AC......

Has the OP said his set is Polish? I think he said the replacement UCL82 is Polish but I don't think we know what the set is.