[Heathkit] SB-401 driver tube shield missing

[Bwana Bob]

I have seen tube shields in old MIL and commercial gear that had holes 
in them or were lines with honeycomb mesh to help the tube run cooler.

Bob WB2VUF

On 12/25/2013 3:10 PM, Drew P. wrote:
>   On Dec 23, 2013, at 12:42 PM, Garey Barrell wrote:
>
>> Rob -
>>
>> You might want to check the manual for your radio before adding a?
>> shield.? That is a hot tube and may have it's life shortened?
>> considerably.? I don't know for sure in the 401, but the Drake TR-4?
>> specifically does NOT use a shield,even though the shield base part?
>> is there.? The extended ring of the base is all the shielding?
>> needed.? Worth checking!
> Similar type of situation with the SB-101 I have here - instability with the shield
>   removed. OTOH, that tube runs awfully hot.  A quick check reveals that the
> driver tube is normally run well in excess of its rated dissipation. I'm considering
> fiddling with the cathode resistor to cool it off a bit - probably at the expense of
> IMD performance.
>
> Drew
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