Continetal 220v radio used on 240v mains

[Old Sparky]

My concern is that the Reservoir/Soothing Capacitor -not the original, but an RS type fitted elsewhere at some time - is only rated at 350vDC(working)-the surge voltage isn't stated. During testing & repair I measures (a) the mains voltage in my workshop (245v), and (b) the surge at switch on (over 400vDC )
both measured with an analogue meter. Whilst the radio has been running OK
elsewhere, should I replace the can with a 500v type?
Relevant to the above, the main HT measures 320vDC after the initial surge, etc. EL84 valves are used as output devices, Is such a voltage OK for these?

[Refugee]

Is it an AC only set or an AC/DC?
If it is AC only it the transformer could get hot after a while. I am looking for a bucking transformer for an item I have that is 220V only.

[ed731pdh]

I can't really see an issue here as the power grid in the UK should be just about harmonised with the continent. 20 volts is not really a lot in the scheme of things. Provided the can is sound and not on its last legs I don't think you will see any performance issues if at all.

[Radio Fixer]

Far harder to mount a bucking transformer in many sets. Much easier are those metal clad chassis mount resistors that can often be hidden away somewhere underneath.

Say 0.25A then that's only 5W for 20V. A 15W device would do fine. It is surprising how much cooler a mains Xformer can be with just 5W diverted from it.

Gary

[Old Sparky]

The Radio in question, a Loewe-Opta Table Radiogram, is an AC only set with a mains TX whose primary is tapped for 110, 127, 160 & 220v. It had worked, presumably for many years in the U.K. before the present owner acquired it, and, on test, after I replaced a couple of faulty capacitors, one a 'woeful Wima' in the mixer/osc. circuit, the other being the FM discriminator 4uf capacitor, has been working OK since I got involved with it. The only other item I've replaced is the filter resistor between the reservoir & smoothing caps. The original is shown on the circuit as being 500 ohm 3 watt. I had a 1k2 vitreous enamel 7W resistor to hand, which I fitted instead of the large 10W RS w/w type that had been fitted elsewhere, the higher value reduces the HT downstream of the smoothing cap. to about 260v, but of course does nothing for the HT to the o/p transformer primaries, and thus EL84 anodes.
I hadn't though of those chassis mount resistors, but could probably find room to mount one on, or under the chassis.

[ed731pdh]

Last time I checked voltages here, a couple of weeks ago, we were harmonised at 225v AC.

[tiv48]

mains voltage to day 244 v0lts so over the week voltage ranged between 240 volts and 245 volts.
rob t

[Radio Fixer]

246.6 volts here !

Gary

[ppppenguin]

Don't forget that in most designs the mains transformer will be run fairly close to saturating the core at the highest specified mains voltage. At this point, even a slight increase in primary voltage will give a disproportionately large increase in current as the core enters saturation. You can check this by monitoring the mains current while adjusting the voltage with a variac. The effect is even more dramatic if you can remove the load from the transformer (unplug all the valves) so that you are looking at just the magnetising current.

Some 220V sets may be fine in the UK, especially if your mains is on the low side. Others may not. A tiny transformer will serve to buck the voltage. For example if you are using a 240V to 20V TX to buck 20V on a radio rated at 100W, the buck TX need only be rated at 8.3VA.

[pwdrive]

Our mains voltage can vary, depends who's got the kettle and immersion heater on. (we are at the end of a rural line)
Back in the 80's in Helston the TV workshop voltage hit over 280 volts, RNAS Culdrose recorded almost 290 volts, we were kept very busy for a year or so, all those marginal smoothers in the old ITT hybrid tv chassis doing weird and wonderful things after a year or so, all the built in thermal fuses in LV transformer in the then new ITT TV's went O/C ITT spares dept could not keep up with our demand for replacements, lost count of the number of freezers that went pop.
Happy days.

Lawrence.