The set will power up but will only bring stations
around 850 kc. There is nothing audible at the lower end or upper end of the dial. No crackle, no nothing.
The set has been re-caped and has been restored somewhat.
Any ideas on how to bring in stations on the ends of
the dial?
BTW - I am running the set off a 2 amp DC supply.
I noticed the set works better off the 7.5 voltage over
the 6 volt setting.
First of all, that design will have some limitations in performance, but will work best with a very long wire for the antenna, and adequate current available to the radio. You will need at least 3 amps (absolute minimum) available. If you do not have adequate current, the vibrator will not operate effectively and burn contact points.
Second, you will have to "peak" your IF's for strongest signal. Trying to tune it without a frequency generator is not the easiest or best, and uaually does not result correct tracking on dial, but if you are looking for best performance, you can do an adequate job without special anything special, it just means your tuning dial may be off.
Third, you will have to tune the radio to your antenna- the capacitor adjustments on the tuning capacitor, or nearby, and make sure the radio is tuned to the top end of the tuning range.
When you get these "tweaks" out of the way, you should get acceptable reception. If you fail to get anything below 850, you will need new "15's" if swapping them first shows zero improvement.
: I got hold of a Zenith 4B 131 6 volt tube radio with
: a multivibrator which sort of works.
: The set will power up but will only bring stations
: around 850 kc. There is nothing audible at the lower end or upper end of the dial. No crackle, no nothing.
: The set has been re-caped and has been restored somewhat.
: Any ideas on how to bring in stations on the ends of
: the dial?
: BTW - I am running the set off a 2 amp DC supply.
: I noticed the set works better off the 7.5 voltage over
: the 6 volt setting.