[Hallicrafters] Halli SX-101A advice

[Carl]

The 6BY6 has superior signal handling ability. It is only a useable swap in 
places where AGC is not applied to the tube as is done to many low end sets 
using the 6BE6.

Carl
KM1H


----- Original Message ----- 
From: "howard holden" <holden7471 at msn.com>
To: "hallicrafters" <hallicrafters at mailman.qth.net>
Sent: Friday, December 31, 2010 2:28 AM
Subject: Re: [Hallicrafters] Halli SX-101A advice


>A comment on the SX-101A saga, and a question for anyone familiar with the 
>A series.
>
> Replaced the power supply and audio cathode bypass caps, radio powered up 
> fine, but no signals. With AF and RF gain full up, only some light 
> microphonics. Noticed the 12BY7A was cold. Popped in a new one, it too was 
> cold. Checked the schematic, and noted that the 12BY7A is the tube which 
> is kept lit all the time along with the heating resistor.  No filament 
> voltage at the tube, none at the separate transformer used for this. 
> Thought the transformer might be bad, but found a completely unattached 
> connection where the fuse for that transformer picks up 120VAC. The wire 
> was just laying there. No sign of it ever actually having been soldered. 
> It apparently was never properly soldered at the factory some 50 years or 
> so ago, but had been laying well enough to make contact, until we moved in 
> August. Connection reattached, receiver is up and running.
>
> Question: In this particular receiver, the 6BY6 pentagrid converter has 
> been replaced by a 6BE6, most likely due to limited (compared to a 6BE6) 
> availability of the 6BY6. Both tubes appear to have the same approximate 
> interelectrode capacitances, and similar operating characteristics. Anyone 
> have a feel for why Hallicrafters chose the 6BY6 instead?
>
> And happy new years to all!
>
> Howie WB2AWQ
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