Joerg said:
Hello Patrick,
Methinks the same. Then it will probably also be difficult to notch it
out by rotating the ferrite rod.
Regards, Joerg
Along with my own kitchen set which I built, I had
3 customers radios going today.
The '56 Grundig hums a bit, an Oz '48 Kriesler hardly hums at all,
a '60 Astor ditto, and mine hums a lot.
Only the Astor has a ferrite rod.
Placing any king of caps across the mains inputs, or from A&N to chassis
makes no difference.
placing 0.01 caps across diodes made zero difference; the noise when tuned to
846 kHz stayed put.
The Grundig improved a lot when its chassis was earthed, like my own design did.
A long wire antenna taken up over the roof was worse.
I can only conclude that where I am, which is only 5Km away from a
5,000 ABC watt AM transmitter, I still have appalling interference on many
sets.
My next step is to try a shielded loop antenna, with the coil inside an aluminium
case
which is carefully prevented from being a shorted turn.
Patrick Turner.