Re: Drake R4B 115VAC Operation
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Bill and all
Yes, I agree - even on my 2B it is 120/240.
It was on an R4C I measured the filament voltage of 7.0 one evening.? Now their mains transformer may have been originally designed for more tubes than what I have got or the later models had. I had thought of putting in a bridge rectifier until I started to use my new box (with autotransformer).? I have not checked what the HT is with 6.6V on the filaments, but the radio works well.
Nigel.
Nigel
On Fri, Nov 24, 2023 at 7:33?PM Jim Shorney < jimNU0C@...> wrote:
Just for fun I did a deep dive and pulled up the R4 manual. There it is in glorious black and white: 120/240v. I wonder where this idea that these radios need 115 or even 110v to be happy comes from? You have to go back to the 1A to see 115v in the manual.
73
-Jim
NU0C
On Fri, 24 Nov 2023 11:10:17 -0500
"Omni" <selcor@...> wrote:
> When all else fails read the manual.? The R-4B is specified to run on 120/240 VAC 50/60 Hz with 60 Watts of power consumption.?
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> From: [email protected] [mailto:[email protected]] On Behalf Of David
> Sent: Friday, November 24, 2023 10:40 AM
> To: [email protected]
> Subject: Re: [DRAKE-RADIO] Drake R4B 115VAC Operation
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> Bill:? You have opened up a very large door here.? If the radio (this is a BIG if) was designed when the standard voltage was 115V (by law and practice) , then the radio was DESIGNED to be used at that input voltage.? The standard today is 120V.? Your voltage now may be +- several % from this actual design voltage. Looking at the radio manual will generally tell you what the input design voltage is.
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> The short issue here is that if you run a radio beyond the designed voltage (with the +- included), then your radio is not running as designed.? So, what does this mean?? ? Let's take filaments on the tubes as an example.? Tube manufacturers use +- 5 to 10 % on this number.? So, if at the voltage you are plugging into is within that range, filament wise you are likely ok.
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> MAny of these radios are transformer powered.? So the B+ voltage (for the plates of the tubes, generally, the higher the input voltage, the higher the plate voltage.? For the most part the ratings of the rectifier diodes and capacitors are generally ok with this.? But take the plate voltage of the 6EH5 tube in the Audio output of the R4 thru R4B radios has a 150 volt max rating.? Measure this and you will see that this voltage is greatly exceeded.? Ever wonder why you changed so many of these?
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> So, the list can go on.? It becomes a real issue when you are dealing with older radios that were designed for the then standard of 110 Volts AC.? Now operating at 120 volts nominal, is a large % of overvoltage.? ?
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> The last factor is where your particular voltage source is generated, transformed and ultimately delivered to your service.? For me, my voltage at any given time is generally between 123 and 126 volts.? THis is dependent on the primary voltage load and the individual load of your service.
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> So, while it is nice to see that you take, for especially the older radios, some care and place them on the variac, it is not a common practice to run these radios on this rating thru the variac forever.? So, your question was real.? The short answer is yes, but the practical answer is no.
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> Welcome to the world of Older radios.? It is FUN!
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> David Assaf III
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> W5XU, VP8RXU
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> On Fri, Nov 24, 2023 at 9:13?AM N3WM - Bill via <n3wm=[email protected]> wrote:
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> Please, is there any advantage to running the R4B receiver on a VARAC for 115Volts?? Maybe less heat I'm thinking...
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> Thanks,
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> Bill N3WM
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> Virus-free. <>
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