[Heathkit] SB-401 driver tube shield missing

[WQ9E at btsnetworks.net]

The Heathkit SB-100/SB-400/HW-100 series definitely need a shield for the 6CL6 which will oscillate wildly if the little clip coming out of the socket doesn't make good contact with the shield.  Although it isn't an IERC type shield it is a dark colored, ribbed, close fitting shield that presumably is designed not to make this already hot class A driver stage run even hotter.  Heathkit indicates in their service notes document for the SB and HW series that poor contact between the driver tube shield and clip are a common cause of instability.

Since this shield was used in a lot of Heathkit gear it shouldn't be too difficult to scare up a proper replacement from a parts unit.

Rodger WQ9E

-------- Original Message --------
> From: Steve Sutfin <stephoto at mind.net>
> Sent: Monday, December 23, 2013 5:41 PM
> To: Garey Barrell <k4oah at mindspring.com>
> Subject: Re: [Heathkit] SB-401 driver tube shield missing
> 
> That's a good point. It reminded me that the 6GK6 driver in my Swan  
> 350C is treated the same. The tube socket has the flange for the  
> shield and whether it did or didn't come from the factory that way  
> most say remove it since it is a hot tube. On the other hand, I've  
> read that if there is oscillation in that stage it might be needed.
> Steve k7dna
> 
> 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!
> >
> > Garey - K4OAH
> > Campton Hills, IL
> >
> >
> >
> >
> > On Dec 23, 2013, at 11:39 AM, Steve Sutfin <stephoto at mind.net> wrote:
> >
> >> Give this a try.
> >> http://www.ultrawebb.com/OHP/
> >> Steve k7dna
> >>
> >> On Dec 23, 2013, at 12:42 AM, Robert Myers wrote:
> >>
> >>> Hi folks,
> >>>
> >>> I am missing the top portion of the tubular metal shield that was  
> >>> used over
> >>> V9, the 6CL6 driver, on my SB-401.
> >>>
> >>> The smaller bottom portion (to accept the bayonet mount top part)  
> >>> is present
> >>> and mounted properly on the chassis -- it's just the top part  
> >>> that is AWOL.
> >>>
> >>> Can someone please tell me where I can get a replacement 6CL6  
> >>> shield that
> >>> will fit properly into this bottom part?
> >>>
> >>> Cheers and Merry Christmas,
> >>> --- Rob Myers
> >>> VE3JQL
> >>>
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