[Amps] HIGH FILAMENT VOLTAGE

[Jim Hargrave]

You can reduce the voltage with parallel back to back diodes in series with each tube filament.
20 amp/40v diodes are cheap and do not present a mounting challenge.

73, Jim – w5ifp at gvtc.com

>> -----Original Message-----
>> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of
>> w8hw at comcast.net
>> Sent: Saturday, December 10, 2016 6:41 PM
>> To: Mike Waters <mikewate at gmail.com>; amps at contesting.com
>> Subject: Re: [Amps] HIGH FILAMENT VOLTAGE
>> 
>> Mike is correct. I have used 27 inch of #18 wire on 3-500 tubes many
>> times and got voltage down to 4.97 volts for each tube. The wire is
>> just one big resistor and gets warm, but works fine. The life of 3-500
>> drops real fast with high filament voltage.
>> 
>> 73, Bruce, W8HW
>> ========================
>> 
>> -----Original Message-----
>> From: Mike Waters
>> Sent: Saturday, December 10, 2016 19:15
>> To: amps at contesting.com
>> Subject: Re: [Amps] HIGH FILAMENT VOLTAGE
>> 
>> No need to use #12. Smaller wire = more compact. A shorter piece
>> of #16 (or maybe even #18), would do fine.
>> 
>> Depends on the current.
>> 
>> 73, Mike
>> www.w0btu.com
>> 
>> On Sat, Dec 10, 2016 at 5:58 PM, kenneth Johnson
>> <wa6rtp at hotmail.com> wrote:
>> 
>> > I used # 12 wire …total of 24 inches long  wound in a two inch coil
>> > placed in each filament lead .
>> > this  droped  the voltage on my henry 2k-3  filaments into
>> specifation.
>> > your problem is finding enough room to get the coil in there.  at
>> any
>> > rate …a length of wire is the way to go.
>> >
>> >
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