Was told a few days back that some manufactures used to connect the antenna to the AC lines through a safety cap. I was thinking of trying that. Any advice please.

50 years ago that was a great idea.
However these days there is so much crap(rf noise on the mains) that it would just swamp the front end of the receiver with noise.
In the old days it was an easy way of having a very long wire antenna.
The health and safety people and other engineers would probably frown, but way out in the country side it may still be an advantage to better reception.
Correctly rated capacitor of course or if you want belt and braces, two in series.
JJ

There should never ever, ever, ever, ever, be a modification on any valve radio that that strings a capacitor between the 240 mains and the aerial front end !!!!!!!!!

I may be an old fuddy duddy but that is a brainless suggestion to put forward.
The thought of a chassis turning up in some ones workshop where some clown has wired any number of capacitors from some point with 240 volt to some point at the front end leaves me gasping...………………..

Its bad enough having unearthed chassis, or wires connected one pin around in the plug, and those pieces of crap with no isolation tranny and live chassis.

Just don't do it!
SAFETY FIRST.

Fred.

The AWA 520M (Fridge) was one that had this fitted as standard. At least, the capacitor was rated at 2000V test and it probably worked at the time.
Harold

What they said. Don't do it.

The unbelievable amount of hash on the mains will come straight in. Not only that, being a capacitor (safety or not), it will leak in a portion of the mains voltage - you don't need that.

If I tried it I would definitely use the proper high voltage safety caps.

If you want to try it safely, just wrap a couple of metres of insulated antenna wire around the power cable.

It certainly wouldn't work where I am, I get massive hash centred on about 600kHz and it moves around.

They were simpler times back then, no MHz range power converters.

PLEASE don't try a capacitor, even a safety one. As Humphrey Appleby said "I predict all sorts of unpredictable consequences"!

I wouldn't recommend doing it. I built a dimmable touch switch from a kit about thirty years ago and I remember there being two of those capacitors in series, so if one capacitor developed a fault, the other would keep the contact with the mains safe. I think the only trick here is that if a fault ever did develop in one of the caps, the end user would still be none the wiser and one day, as Mr Murphy would predict, the other would probably short out too.

I see no reason for this. Capacitors between active and earth or active and antenna will not remove hum or interference, so it is not only potentially dangerous but also unproductive.

Yes, in consideration Ian’s suggestion is the safest.
And, is regularly done to improve FM radio reception.
Unfortunately the lack of proper regulations control recently in Australia, has allowed a lot of gear in that has exactly that.
Capacitors connected directly to mains!
JJ

A lot of American sets have no transformer & rely on Neutral as the ground return for RF. That normally requires a line cap in series with any external antenna.

The death trap here is that most of the early non- transformer "Hot Chassis" sets had a two pin plug that could be reversed. That meant that active ended up on the chassis. Later sets "floated" the chassis, but a reversed plug brought active into play.

Anyway guys thanks for the input I might just leave this idea alone.

I might just leave this idea alone

Apply the reverse Nike slogan: Just don't do it.

It would be interesting to get one of those caps from the AWA & expose it to 1KV from one of the insulation testers. Its probably a waxed paper containing a bit of PCB as the self healing agent, and by now, it probably leaks like a sieve. Definitely "side cutter" fodder.

Consider that all those Chinese bedside lamps with touch on/off function have probably only one cap in series and probably not a particularly high quality one at that.

I was at a hotel the other day which had one of them and you could definitely feel a tingle when switching it on or off.