[Hammarlund] Re: Tube shields? We don’t need any stinking tube shields!

[Les Locklear]

If I had a bunch of the "Real" IERC shields, I would use them, but I'm not 
about to pay the price they seem to sell for these days. No shields seems to 
work for me.

Les
----- Original Message ----- 
From: "rbethman" <rbethman at comcast.net>
To: "Les Locklear" <leslocklear at cableone.net>
Cc: <r-390 at mailman.qth.net>; <Hammarlund at mailman.qth.net>
Sent: Monday, December 03, 2007 4:40 PM
Subject: Re: Tube shields? We don’t need any stinking tube shields!


> Les,
>
> While I do not have the sophisticated temperature measuring capabilities, 
> I have long suspected that the results you've posted was the case.
>
> I long done away with those pesky shields, both in R-390As and SP-600s.
>
> They DO seem to run cooler!
>
> Bob - N0DGN
>
> Les Locklear wrote:
>> Groups,
>>
>> This test was done using a Raytek laser digital thermometer. Temperatures 
>> were taken from a 6BZ6 1st RF amp tube on a John R. Leary SP-600JX no 
>> suffix number, serial number 1262. Ambient room temperature was 75°F. I’m 
>> not a scientist nor should this be misconstrued as a scientific test. I 
>> have always been curious as to whether the IERC tube shields “actually” 
>> prolong tube life. As noted there were several different tube shields 
>> used in this “test.” Also note there are several different types of 
>> inserts inside these tube shields.
>>
>> The “Real McCoy” IERC Tube Shields have a finger grip type of insert that 
>> acts as a heat sink and the test results show that the temperature 
>> difference between the shield and the tube itself is little. That should 
>> tell us that that type of shield is the “Standard.” For your information, 
>> I don’t use tube shields and my tubes seem to last a long time.
>>
>> Take this information as it’s meant to be, strictly informational.
>>
>>  1.. Shiny metal Eby tube shield no insert. 94°, bare tube 124°F.
>>
>>
>>  2.. Shiny metal Eby tube shield with seven-sided black aluminum insert. 
>> 96°F, bare tube 127°F.
>>
>>
>>  3.. Dull metal Elco tube shield no insert.108°F, bare tube 135°F.
>>
>>
>>  4.. Black heat resistant painted Eby tube shield no insert. 104°F, 126°F 
>> bare tube.
>>
>>
>>  5.. Black anodized Eby tube shield with “waveform, nine ridges” aluminum 
>> black heat shield insert. 107°F, bare tube 127°F.
>>
>>
>>  6.. Collins black anodized tube shield with “waveform, nine ridges” 
>> aluminum black heat shield. 100°F, bare tube 122°F.
>>
>>
>>  7.. W.P.M. tube shield with five-sided aluminum insert. 106°F, bare tube 
>> 118°F.
>>
>>
>>  8.. IERC tube shield with “finger grip” type beryllium insert. “The 
>> Standard.” 102°F, bare tube 104°F. ( has to be the insert)
>>
>>
>>  9.. Bare tube, no shield. 6BZ6 114°F.
>>
>
>
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