[Hammarlund] SP-600 NuvistaPlug & more

[jeremy-ca]

Im guessing that it and the 150 Ohm resistor is used more as a rudimentary 
suppressor for VHF parasitics since the circuit has no neutralization or 
other suppression which is included in many other cascade designs.

The gain is also kept low, possibly as a method of stabilizing.

Carl
KM1H



----- Original Message ----- 
From: "K9FFK" <k9ffk at comcast.net>
To: "Al Parker" <anchor at ec.rr.com>
Cc: <kgordon2006 at verizononline.net>; "Hammarlund List" 
<hammarlund at mailman.qth.net>
Sent: Saturday, November 10, 2007 12:31 PM
Subject: Re: [Hammarlund] SP-600 NuvistaPlug & more


> Al Parker wrote:
>> Hi folks,
>>    We also have that on The Hammarlund Historian website, in the 
>> 'H-Files" section.
>> for a "deep link" go to: 
>> http://www.hammarlund.info/info/sp-600/tech-bulletin-107/
>>    ...snip...
>>
>> ----- Original Message ----- From: "Kenneth G. Gordon" 
>> <kgordon2006 at verizon.net>
>> To: "Todd, KA1KAQ" <ka1kaq at gmail.com>
>> Cc: "Hammarlund List" <hammarlund at mailman.qth.net>
>> Sent: Wednesday, November 07, 2007 4:26 PM
>> Subject: Re: [Hammarlund] HQ-129 and 717A mod and SP-600
>>
>>
>>> ...snip...
>>> Hee hee! Here you go!
>>>
>>> <http://www.mines.uidaho.edu/~glowbugs/SP600upgrd.pdf>
>>>
>>> I see it was originally printed in a military technial manual...
>>>
>>> Ken W7EKB
>>
>>
>> _______________________________________________
>> List Administrator: Duane Fischer W8DBF
>> ** For Assistance: dfischer at usol.com **
>> ----
>> http://mailman.qth.net/mailman/listinfo/hammarlund
>>
> Has anyone ever looked at this schematic and asked why there is a 50pf 
> (fifty) on the output (pin 5)?
> The 6BA6 Cout (shielded) is given as 5.5pf. The 6CW4/6DS4 Cout is given as 
> 1.8pf.
> The difference is 3.7pf. So a replacement would need an additional 3.7 pf 
> on pin 5 (5pf is close enough).
> I've looked at my Nuvistaplug and indeed there is a 50pf on the output. 
> Why?
> Would/does this not seriously detune the tuned circuit? It certainly is 
> quieter!
> What gives?
>
> Dick K9FFK
> _______________________________________________
> List Administrator: Duane Fischer W8DBF
> ** For Assistance: dfischer at usol.com **
> ----
> http://mailman.qth.net/mailman/listinfo/hammarlund
>