[ARC5] Added 6F6 audio stage.

[mac]

A 12A6 has plenty of capacity to drive a speaker.  The audio gain  
shortfall complaint with command set receivers and others such as the  
BC-348 voiced by (some) hams is due to the absence of an intermediate  
audio amplifier between the 2nd detector and the audio output stage as  
found in most standard superhet designs of the era. Usually a triode  
stage but not always (high gain pentode in the AR-88 for ex).  The  
extra gain was not needed in most aircraft sets where headphones were  
the norm.  This subject comes up about once a year on these forums.

On Oct 19, 2012, at 4:03 PM, Geoff wrote:

> Maybe he wanted enough audio to drive an old 12" console speaker.
> I drove a small 5x7 auto speaker with the 12A6 in the 50's and it  
> wasnt very
> loud.
>
> Has anyone measured the distortion of a stocker?
>
>
> ----- Original Message -----
> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
> To: <Arc5 at mailman.qth.net>
> Sent: Friday, October 19, 2012 2:35 PM
> Subject: [ARC5] Added 6F6 audio stage.
>
>
>> Someone here mentioned that he owns an ARC-5 receiver which has an  
>> added
>> 6F6 audio
>> stage on the "back porch", and a 6J5 where the 12A6 is supposed to  
>> be.
>>
>> Undoubtedly, that comes from an article entitled "New Life for the  
>> Q5er"
>> by Douglas R.
>> Jordan printed in QST for February 1951 beginning on page 37.
>>
>> All the mods detailed in that article could be applied to any of the
>> models, not just the BC-
>> 453.
>>
>> All I can say is, "Whew!", and "Crap-ola". :-(
>>
>> That article might be a help for the owner to "un-hack" or "reverse- 
>> hack"
>> his receiver.
>>
>> Maybe...
>>
>> One thing I found rather interesting about the article is that the  
>> author
>> used a hacksaw to
>> remove the dynamotor mounts, when all that is really required is a  
>> small
>> pipe-wrench to
>> simply unscrew them.
>>
>> Gee...whatever happened to the KISS principle?
>>
>> Ken W7EKB
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>
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