Carl,
That is good info. If I ever need a NOS resistor for my 1925 "Walbert
Issofarad" 4 stage TRF, I'll know who to contact.
73, Jim - w5ifp@gvtc.com
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl
>> Sent: Sunday, December 21, 2014 7:17 PM
>> To: Hardy Landskov; Colin Lamb; Bill Turner; Amps group
>> Subject: Re: [Amps] THE SKINNY ON MY AL-82
>>
>> You havent lived until you find a 47K that became 1-2 Meg which is quite
>> common in many old receivers and sourced at only 200-250VDC as screen
>> droppers.
>>
>> Over 50+ years of building and servicing tube gear Ive only found a
handful
>> that went down in resistance.
>>
>> I have a conservative 10K of NOS carbon resistors and about half again in
>> used condition going back to the late 20's
>>
>> Carl
>> KM1H
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Hardy Landskov" <n7rt@cox.net>
>> To: "Colin Lamb" <k7fm@teleport.com>; "Bill Turner"
>> <dezrat@outlook.com>; "Amps group" <amps@contesting.com>
>> Sent: Sunday, December 21, 2014 5:19 PM
>> Subject: Re: [Amps] THE SKINNY ON MY AL-82
>>
>>
>> > It's been my experience that the 2 watt ones are the worst. I measured
>> > 1 meg resistors that have drifted up to 2.5 megs.
>> > So, think your high voltage is low and your power supply is going
south?
>> > Measure the resistors first that feed the voltmeter.
>> > 73 N7RT
>> >
>> > ----- Original Message -----
>> > From: "Colin Lamb" <k7fm@teleport.com>
>> > To: "Bill Turner" <dezrat@outlook.com>; "Amps group"
>> > <amps@contesting.com>
>> > Sent: Sunday, December 21, 2014 2:46 PM
>> > Subject: Re: [Amps] THE SKINNY ON MY AL-82
>> >
>> >
>> >> Regarding carbon comp resistors:
>> >>
>> >> "Not necessarily. Carbon comp resistors can drift both up and down in
>> >> value. I've been replacing them all my life, trust me on this one.
>> >> They are essentially unpredictable."
>> >>
>> >> Many years ago, I tested some 2 watt 250 ohm carbon comp resistors
>> >> for stability. I heated them up to dissipate 2 watts in open air.
>> >> After a relatively short period of time (I do not recall the time,
>> >> but it was a number of minutes), I measured the resistance and it had
>> >> increased. I thought I could go through a number of cycles and have
it
>> stabilize.
>> >> But, every time I ran it through a cycle, the resistance changed. At
>> >> first, it went up in resistance. But, soon it started going down.
>> >> It never was stable. And, each resistor was different.
>> >>
>> >> I have numerous old Allen-Bradley 1/2 watt resistors on the shelf and
>> >> some are stable, while some are not.
>> >>
>> >> Colin K7FM
>> >> _______________________________________________
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>> >> Amps@contesting.com
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>> >>
>> >
>> >
>> > _______________________________________________
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>> >
>> >
>> > -----
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>> > 12/21/14
>> >
>>
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