Nichrome wire would have to dissipate 75 watts of heat unless it was mounted on
stand-offs with air flow. Otherwise that heat will go directly to the socket
thus quickening their demise as they lose spring tension on the filiment
sockets. Which happens anyway, but this will speed it right along. Or you might
just swap a tube to figure out which is bad and you're done ...with 50/50 odds
of getting it right the first time. Sometimes the most obvious method is the
best one. And not all pairs of 3-500's have filaments in series.MarkWa3jpyWho
has changed many many 3-500's
-------- Original message --------From: Adrian <vk4tux@gmail.com> Date: 3/20/20
10:50 (GMT-05:00) To: Jim Thomson <jim.thom@telus.net>, amps@contesting.com
Subject: Re: [Amps] Henry 2K-4 Failure Yes I earlier divided 10 volts by 15
amps to get 0.666 series resistance divided by 2 (tubes)1.5 ft 16 gauge
nichrome coiled is a inexpensive option.On 21/3/20 12:16 am, Jim Thomson
wrote:> ## would require a .333 ohm at 75+ watt resistor.>> Jim
VE7RF>>> -----Original Message----- From: Adrian> Sent: Thursday, March 19,
2020 3:17 PM> To: Jim Thomson ; amps@contesting.com> Subject: Re: [Amps] Henry
2K-4 Failure>> Thanks Jim, you can't beat words from those experienced.>> I
guess a cathode test plug could be made to substitute one tube> plugging into>>
the socket .A dead tube could have its base made up for this, with> resistor
added to>> cathode connections equalling the hot value.>> Then interchange
tubes on the remaining socket to compare.>>>> vk4tux>>>>> On 20/3/20 3:32 am,
Jim Thomson wrote:>>> Grid to cathode short & ?stayed failed? means you just
need an>>> ohmmeter. No need to swap tubes, etc.>>>>>> Gerald, VE1DT>>>>> ##
Nope. The grid to cathode short only happens with tube >> fil lit.....
not when cold.>> When cold, both a HI pot tester.... and also a
megger wont >> work either.>>>> Jim VE7RF>>
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