[Amps] HIGH FILAMENT VOLTAGE

[Richard Solomon]

And a piece of Nichrome Ribbon/Wire
from a broken Toaster is free.

73, Dick, W1KSZ

On Sun, Dec 11, 2016 at 3:45 PM, Jim Hargrave <w5ifp at gvtc.com> wrote:

> 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 at gvtc.com
>
>
>
> >> -----Original Message-----
>
> >> From: w8hw at comcast.net [mailto:w8hw at comcast.net]
>
> >> Sent: Sunday, December 11, 2016 2:08 PM
>
> >> To: Jim Hargrave <w5ifp at gvtc.com>; 'amps'
>
> >> <amps at 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 at gvtc.com> w5ifp at gvtc.com
>
> >>
>
> >> >> -----Original Message-----
>
> >> >> From: Amps [ <mailto:amps-bounces at contesting.com> mailto:
> amps-bounces at contesting.com] On Behalf
>
> >> Of
>
> >> >>  <mailto:w8hw at comcast.net> w8hw at comcast.net
>
> >> >> Sent: Saturday, December 10, 2016 6:41 PM
>
> >> >> To: Mike Waters < <mailto:mikewate at gmail.com> mikewate at gmail.com>;
>
> >>  <mailto:amps at contesting.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:  <mailto:amps at contesting.com> 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
>
> >> >>  <http://www.w0btu.com> www.w0btu.com
>
> >> >>
>
> >> >> On Sat, Dec 10, 2016 at 5:58 PM, kenneth Johnson
>
> >> < <mailto:wa6rtp at hotmail.com> 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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>
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>
> >> >>
>
> >> >> _______________________________________________
>
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>
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>
> >>
>
> >> _______________________________________________
>
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>
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