[Hallicrafters] SX101A 50.75KC IF Amplifier

[Mark K3MSB]

Roger --

Yes, I knew it was to reduce the gain,  but why just for the 1 KHz
position?  I wouldn't have been surprised to see if for the 1 and
lower, or the 1 and higher, positions.  I can't see anything in the
schematics that makes the 1 KHz position "special" !!

Mark K3MSB

On Wed, Dec 31, 2008 at 5:24 PM, Rodger <wq9e at dtnspeed.net> wrote:
> Mark,
>
> This is used to reduce the gain a little at this setting in order to avoid
> much higher gain at the 1 Khz. position as compared to the other selectivity
> positions.  Although the gain does vary a little between the various
> positions in a well aligned SX-101 the difference is fairly small.  This is
> used in other Halli receivers using the 50 Khz. IF including the SX-100 and
> SX-115 also.
>
> Rodger WQ9E
>
> Mark K3MSB wrote:
>>
>> If one looks at the schematics for the SX-101A, specifically the rear
>> wafer (S5A Front) for the Selectivity switch, I notice that the
>> Hallicrafters engineers switch in a 470 ohm resistor (R31) for the 1
>> KHz selectivity setting only.    This adds an addition 470 ohms to
>> cathode and grid of V6, for the 1 KHz setting only.
>>
>> I'm curious as to why they do this for just the 1 KHz setting only,
>> and none of the others.
>>
>> Mark K3MSB
>> ______________________________________________________________
>>
>>
>>
>
>