[ARC5] BC-453 B dynamotor hum
Kenneth G. Gordon
kgordon2006 at frontier.com
Sun Nov 1 11:30:24 EST 2015
On 1 Nov 2015 at 15:24, J Mcvey via ARC5 wrote:
> The problem only occurs when the radio gets warmed up.
> Uh-oh could this be a bad output transformer arcing internally? There isn't much
> else to the 12a6 circuit! HELP!!!
Hmmm....I too have yet to find a "bad" 12A6.
But audio transformers are one of the particularly unreliable elements in the
ARC-5 receivers, so that is a possibility. In fact, in my hacked-up pile of
rejects, bad, or completely missing, audio transformers show up regularly. I
would guess that at least 1/3 of the receivers I have here have bad audio
transformers.
However, one of the easiest and quickest checks you can perform is to
simply try a new 12A6. Doing so would eliminate that from concern.
Do you have any extra 12A6s? If not, I can send you one. I have a box of
NIB tubes for the receivers which I received in that estate that was given to
me many years ago. The only tubes in that pile which are "rare" are the
12SF7s....of course... :-(
Ken W7EKB
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