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dim bulb tester - Zenith 775B - Printable Version

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dim bulb tester - Zenith 775B - mg34.42 - 12-23-2021

can anyone tell me what wattage of bulb to use for a 11-tube radio 
benny

(title edited by admin for clarity)

RE: dim bulb tester - GarySP - 12-23-2021

Need a little more info. Can you provide a manufacturer and model number? Take care and BE HEALTHY! Gary

RE: dim bulb tester - mg34.42 - 12-23-2021

its for a zenith 775B

RE: dim bulb tester - Zenith 775B - GarySP - 12-23-2021

Took a quick look at the schematic for a zenith 775B. The pilot lamp is a part of the heater string. The string is operated at 2.5 volts. If the base is screw-in I would try a #41 lamp. If it is a bayonet base then a #43 lamp. Both are rated 2.5 volts and 0.5 amps. Hope this helps. Take care and BE HEALTHY! Gary

RE: dim bulb tester - Zenith 775B - GarySP - 12-23-2021

Oops! Just realized you may have been inquiring about the wattage to use in a dim bulb tester. Rule of thumb is to use a bulb with wattage 1.5 to 2.0 times greater than stated wattage on the chassis identification plate. If you don't have that information, try subbing bulbs until the lamp glows dimly while the radio is operating. Too low a bulb wattage and it will glow brightly without the radio operating. I would start with a 75 watt bulb. A good tutorial can be found online. Type in "dim bulb tester", then open the "powering your radio safely with a dim - bulb tester". Personally, I would invest in a Variac for powering up a radio instead of a dim-bulb tester. Hope this helped. Gary

RE: dim bulb tester - Zenith 775B - radiorich - 12-23-2021

Hello Gary,
Nice to know that info too .

Sincerely Richard

RE: dim bulb tester - Zenith 775B - mg34.42 - 12-23-2021

on the back of the radio, it states 130 watts

RE: dim bulb tester - Zenith 775B - GarySP - 12-23-2021

In that case, I would use a 150 watt lamp. Not the most common of bullbs in that wattage. Another reason to invest in a Variac. Take care and BE HEALTHY! Gary

RE: dim bulb tester - Zenith 775B - mikethedruid - 12-23-2021

The old "dim bulb testers" usually didn't have just one Edison socket, but several sockets in parallel, at least three, and then this bank in series with the hot side of the line, both from the plug and to the outlet. This allows one to use a combination of tungsten filament lamps to provide the desired resistance, and saves buying odd wattages.

RE: dim bulb tester - Zenith 775B - Arran - 12-24-2021

They are easy enough to construct, the difficulty is in finding incandescent light bulbs. What I did was make an extension cord with a pair of standard electrical outlets, and wired it so the bulb filament was in series with the hot side of the line, then I could plug a table lamp into it. If you do it this way you can use a lamp with a trilight bulb, and switch in the desired wattage in stages, trillight bulbs were exempt from the silly bans.