Regal Radio 747 Repair Part 1, Circuit Description.
Regal Radio 747 Repair Part 1, Circuit Description
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Regal Radio 747 Repair Part 1, Circuit Description.
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Thanks saturn5tony
Thanks 3mustardMoNkEyS The main bias for the 1S5 is on pin 6, 10MEG and the
560 ohm resistor. Pin 3 is a diode plate, hard to see in the drawing. The
47K and 1MEG (volume control) is the rectified audio path from pin 3 to the
filament. The 0.0001MFD is the RF drain. The 22MEG and the .05 MFD made an
RC time constant for the negative AVC voltage.
Thanks ON4AAH
Very informative, question: The 1M resistor next to the 1S5 tube, that just
sets the “cutoff” point to which the 0.0001microFarad cap drains away the
RF(due to reactance), or is it just there for biasing to the audio amp?
Very cool portable tube radio !!!
Thanks wolfhawg
Thanks rafalrrrr
Wow batteries use to be made in USA?
Amazing. This is so small. Again Rick, your explanations are outstanding.
So many Electronic Instructors could have saved days of blackboard
explanations using your techniques with the PC, drawings and verbal
explanations. Looking forward to part 2 very much… Thank you!! Tony
Thanks jeanious2009
Thanks joernone Hey John, As you know every fix is different and this one
is not starting out good, three burned out tubes. I hope I can find enough
tubes to work on it. But thats the way it is. I don’t know why I like tube
portable radios, maybe I need the extra aggravation. Regards, Rick
Thanks CameramanLink I think those batteries would have been avaliable in
the late 1940s and through the 50s and 60s. Yes storing the batteries above
the radio chassis is not a good idea.
Thanks UmaBlinky Yep, it does look like a lunch box. I’m Hungry.
Thanks muddymuddymuddmann
Really like the schematics and the explanations. I am a EE but people like
you have taught me so much about this old technology through their videos.
Thanks ISUZU1987 Hope you find it.
Rick, Having just come off that Motorola 5A7A repair job, I’m glad it’s you
fixing this one. The parts in those old, small portables are really crammed
in there. There was one last cap that needed changing, but it was buried
down in there, meaning a hundred things had to be moved out of the way.
When I finally reached it the darn thing it turned out to be the
oscillator…same color and appearance as the caps. :=) Looking forward to
hearing yours play. Regards, John
JUST LIKE A SMALL JOURNEY ADVENTURE THROUGH THE RADIO. GREAT VIDEO. I LOVE
THE AVC CIRCUIT. TUBES SEEM SO MUCH EASIER THAN TRANSISTORS. ELFs AND EMPs
WONT HURT THE TUBES THAT MUCH. TRANSISTORS WILL BLOW IN A MILLISECOND.
TUBES RULE. GLOW IN THE DARK RADIOS WILL MAKE IT THROUGH. I SURE WISHED MY
HEATHKIT WAS WORKING. I MISS TALKING ON 75 METERS. THE POWER SUPPLY KEEPS
TRIPPING THE CIRCUIT BREAKER. BIG DRAIN SOMEWHERE. MUDDy
Thanks MrHorsetail No alkaline batteries yet.
Thanks conoba
Very interesting, i hope you fint it, thanks.
Thanks for explaining this circuit. I’d bet those batteries didn’t last
long powering all those tubes.
that make me recall that my mom has a little am raido it was my grandad but
the raido is made by BFGoodrich it was his wen he was in the nave well he
now in hes 80 so is my grandmother but the raido last time I plug it in
noth’in hapend I no in the late 90″s it was work’in fine I need to see if
she still has it she sed that I could have it three or for year’s back I
just did won’t miss place it
Where do you find the circuit diagrams for all of these radios you work on?
I would have thought they’d be nearly impossible to locate, especially the
ones manufactured close to 80 years ago. Thanks for another great video.
Hi Rick Great explanation. Thanks for another great video.
Thanks ms2333 Google “nostalgiaair”