I said Late 20's Jim! While I have several battery sets I just display a
couple of them and havent bothered to get one going.
My interest is AC powered and my oldest is probably 1927; most of my
collection is 1930 to about 1970 with a mix of consumer, ham, commercial,
and military.
Carl
KM1H
----- Original Message -----
From: "Jim Hargrave" <w5ifp@gvtc.com>
To: "'Carl'" <km1h@jeremy.qozzy.com>; "'Amps group'" <amps@contesting.com>
Sent: Tuesday, December 23, 2014 5:33 PM
Subject: RE: [Amps] THE SKINNY ON MY AL-82
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
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
>
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