Next for my attention was a more permanent power supply, batteries not being available any-more.
I could make up a battery bank of sorts but with infrequent use, this would be waste of money and there is always the risk of them leaking and therefore corroding everything.
I can do without that.
I suppose my Dad's radio room alive with the buzz of battery vibrators is the cause of my obsession with the things. I have collected many rotary power supplies and vibrators over the years.
I even have a supply for a Spitfire, but as I see two more coming up in an auction, there goes the value for that up in the air. There is one for £2000 in England, but I don't suppose there are many Spitfires left needing a genuine war radio.
I digress.
I have a few power supply/audio amp chassis from car radios where the tuner and volume control is mounted in or under the dash but the supply, amp and speaker are mounted on the firewall.
I selected a 6 volt version. The vibrator had already been dismantled in the past. (Not a good sign)
I spent ages getting it to vibrate as the contacts had been “adjusted” by someone without much knowledge of their operation.
I had no more of 4 pins 6 volt vibrator units.
Now a perplexing situation occurred.
Applying the battery would see the voltage from the transformer come on immediately and as the rectifier valve warmed up, so too the B+ of around 225 volts, probably OK, BUT after a few minutes the voltage would fade to around 35 volts and the leads from the battery became exceptionally hot, the vibrator would slow and stop. Something was wrong.
Then after many starts, I could smell the transformer.
I concluded there was/were a shorted turn/s inside. Next, please.
I had only 12 volt versions now, but as the BC221 needed 135 volts, not the full 275 or so that a car radio would use.
I wonder?
Plugging the 6 volt vibrator can into the 12 volt chassis, I connected the truck battery (with a fuse) and was greeted with the steady hum of the vibrator.
The rectifier valve was rewired for 6 volts and the audio amp valve removed.
The voltage came up around 150 volts DC with no load, unbelievable!
I had replaced every condenser in the 6 volt chassis as a precaution before applying the battery, this 12 volt chassis I did nothing to at all before testing it.
Connected to the BC221 the voltage fell to around 100, near enough to a slightly flat battery pack.
I now changed a few condensers and fitted a new braided metal shielded battery lead and two old clips.
I gave the shiny woven braid a spray with flat black, after all, I don't want the enemy seeing the sun glinting off it, do I?
I slid the vibrator power chassis into the battery compartment and wired it.
The Frequency Meter works well with the added bonus of the vibrator hum.
The headphone repair will be in the next post.