[ARC5] Fw: 6k8 - 12k8?

[Henry Mei'l's]

----- Original Message ----- 
From: "Henry Mei'l's" <meils at get2net.dk>
To: <kgordon2006 at frontier.com>
Sent: Saturday, April 16, 2011 10:04 PM
Subject: Re: [ARC5] 6k8 - 12k8?


> Couldn't that shorted state  thus be intermittent
> and consequently, shaking/rattling the tube might
> open/close the short; easily seen on an ohmmeter.
> I'm not recommending that the tube be used
> even if could be shaken to "normal."
>
> Henry
> oz3o n2nr
>
> ----- Original Message ----- 
> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
> To: "ARC-5 List" <arc5 at mailman.qth.net>
> Sent: Saturday, April 16, 2011 8:31 PM
> Subject: Re: [ARC5] 6k8 - 12k8?
>
>
>> On 16 Apr 2011 at 10:23, Dennis Monticelli wrote:
>>
>>> I have another theory.  That may be a correctly built 12K8 with half
>>> the filament shorted upon itself.  Your typical filament is folded
>>> (often more than once) before it is inserted into the cathode sleeve.
>>> When the insulating oxide coating on the filament breaks down or
>>> flakes off, it sometimes makes contact with the sleeve (heater to
>>> cathode leakage) but it can also make contact with its folded self.
>>>
>>> Dennis AE6C
>>
>> Hmmm....good point, and certainly not impossible. The trouble is, to 
>> prove
>> this, one would have to dismantle the tube under a microscope, whereas we
>> DO know that tubes have been mislabeled in the past.
>>
>> Ken W7EKB
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