There are several ways to fix this one. I mentioned Diodes because I know it
works. It may not be the best solution, but is a simple way to obtain a volt or
so drop. A bridge rectifier takes up a small chassis space and a 50 amp block
will support 2x3-500 or 2x4-400 tubes. They are in the $3 +/- range
Here is an example.
http://www.newark.com/multicomp/gbpc5006/bridge-rectifier-single-phase/dp/51T1789?MER=sy-me-pd-mi-alte
73, Jim – w5ifp@gvtc.com
>> -----Original Message-----
>> From: w8hw@comcast.net [mailto:w8hw@comcast.net]
>> Sent: Sunday, December 11, 2016 2:08 PM
>> To: Jim Hargrave <w5ifp@gvtc.com>; 'amps'
>> <amps@contesting.com>
>> Subject: Re: [Amps] HIGH FILAMENT VOLTAGE
>>
>> Caution... Yes you can but... In the case of 3-500 tubes each diode
>> would dissipate 8.5 watts (14 amp * .6v) so for Continues use, you
>> would need 15 watt or better yet 25 watt diodes and that would be
>> chassis mount. They are not cheep. Less than that, they could short
>> and you would never know it as the amp might still work, just the fill
>> voltage issue not fixed.
>> Additionally voltage spikes can happen causing the diodes to fail
>> where 18 ga wire survives.
>>
>> 73, Bruce, W8HW
>>
>>
>> -----Original Message-----
>> From: Jim Hargrave
>> Sent: Saturday, December 10, 2016 23:38
>> To: 'amps'
>> Subject: Re: [Amps] HIGH FILAMENT VOLTAGE
>>
>> 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 – <mailto:w5ifp@gvtc.com> w5ifp@gvtc.com
>>
>> >> -----Original Message-----
>> >> From: Amps [ <mailto:amps-bounces@contesting.com>
>> >> mailto:amps-bounces@contesting.com] On Behalf
>> Of
>> >> <mailto:w8hw@comcast.net> w8hw@comcast.net
>> >> Sent: Saturday, December 10, 2016 6:41 PM
>> >> To: Mike Waters < <mailto:mikewate@gmail.com> mikewate@gmail.com>;
>> <mailto:amps@contesting.com> amps@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: <mailto:amps@contesting.com> amps@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
>> >> <http://www.w0btu.com> www.w0btu.com
>> >>
>> >> On Sat, Dec 10, 2016 at 5:58 PM, kenneth Johnson
>> < <mailto:wa6rtp@hotmail.com> wa6rtp@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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>> >>
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