[ARC5] Why "Noodling" About Sweep Tubes

[Geoff]

The H&K 257B was developed before Eimacs copy and was also given the JAN 
4E27 designation. They call it a Beam Pentode and also give ratings for 
suppressor grid modulation. The H&K 57 is another listed the same way and 
otherwise looks like a 4-65A; I think Penta made a pentode version in later 
years.

Another little used tube is the 814/VT-154 which often shows up NIB on 
Fleabay ultra cheap especially with just its VT-154 designation. Tall and 
skinny, beam power tube with suppressor grid brought out seperately, think 
of a 813JR. Uses same socket as an 807. I can easily run 125W out on AM in 
either of my Hallicrafters HT-9's with no strain.

Carl




> "Although they are 'beam tubes' their advantage over other types of beam
> tubes is that their beam-forming plates are connected to separate pins, 
> and
> not to the cathode, as all octal-based beam-tubes are."
>
> Not sure about this: the 4-125A is a tetrode, and the 4E27 can manage
> suppressor grid modulation, which would seem to suggest more of a
> traditional g3?
>
> 73, ian K3IMW
>
>
> On Tue, Oct 22, 2013 at 2:13 PM, Kenneth G. Gordon
> <kgordon2006 at frontier.com> wrote:
>> Bill is certainly right about the 4E27 and the 4-125 and its pulse 
>> variants. I
>> had forgotten about those. Either would be perfect for your uses, and 
>> both
>> are cheap on eBay, especially the pulse variants which are not as easily
>> recognized.
>>
>> There was a later variant of the 4E27: the 5-125B/4E27A. Those often show
>> up too, but sell for higher prices.
>>
>> The PD of the 4E27 is 75 watts, while that of the 4E27A is 125 watts.
>>
>>
>> Either one uses an 813 socket.
>>
>> Although they are "beam tubes" their advantage over other types of beam
>> tubes is that their beam-forming plates are connected to separate pins, 
>> and
>> not to the cathode, as all octal-based beam-tubes are.
>>
>> Ken W7EKB
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