Huge Lesson Learned!!!

[Bushbaby]

Hi All,
Thanks for the info Joe regarding your VHF 90 which has helped.
The second thing is that I was following the wiring of another ivory VHF90 whilst having a 3rd radio in poor condition and untouched as a reference which I haven't looked at properly until today and I wished I had! The 2nd ivory radio that I was following has been wired incorrectly around the mains dropper section/tag board so it is no surprise that it hasn't worked!!!

I have now rewired the offending tag board but before I proceed further I had previously removed C66 (0.05uF suppressor as in the trader sheet) as recommended. I've noted that this is connected to the chassis earth - do I need to wire across this now that cap is removed to restore the connection to the chassis??

Regards

Rob

[Joe]

NO! That would dump the whole mains across the dial lamps and shunt. Just forget about that one, at least until the set is working. I left it out of mine and that works fine.

- Joe

[pwdrive]

Just in time there Joe...

Lawrence.

[Bushbaby]

Thanks Joe,
I wasnt sure so I thought I would ask. Does this not cause an issue with regards to earthing?

Thanks

Rob

[pwdrive]

Only so far as mains borne interference goes, as Joe has said, with the mains suppresor capacitor disconected the receiver will still work ok once the receiver is up and running. If you decide to replace the mains suppressor capacitor then it should be replaced with an X rated type.
Are you familiar with what a capacitor does?

Lawrence.

[Joe]

No. All that capacitor was for was to supposedly suppress mains-borne hum. In practise they do nothing but wait their opportunity to explode and make you soil yourself.

- Joe

[Skywave]

Y'know, I've never been really sure about the reason for fitting that cap. across the mains input: I always thought that it was primarily there to by-pass any high-frequency 'noise' - such as fast-rising spikes, random R.F. signals and such like coming down the mains lead. As for suppressing hum - as in modulation hum - the usual trick consists of capacitor(s) from the anode(s) of the rect. valve to chassis.

Have I got all that about right?

Al.

[Bushbaby]

Hi All
SUCCESS! - its working on MW and I've just been listening to 5 live. Its a wee bit 'buzzy' at present and its doesn't appear that the VHF side is working just yet. I'm getting a hum but no stations - any thoughts??

Regards

Rob

[pwdrive]

That's good news Rob, my own take would be to get the whole think up to spec on AM then have a look at the FM problem.

Lawrence.

[Bushbaby]

Yes, VHF isn't working at all. It seems that 5 live is the strongest station and its crackly as well as slightly buzzy. My garage might not be the best place for reception and I'm running it off the isolation transformer at present.

At least it has some life though!

Rob