[Hallicrafters] sx 42 S meter reading

[W7QHO at aol.com]

In a message dated 4/17/06 9:17:26 AM, paxhkv at wxs.nl writes:


> The S meter reading on my recapped and aligned SX 42  is rather low . It 
> does not exeed S 9 even not on the strongest BC stations...........
> 

Hans,

The S meter in the SX-42 operates by measuring the combined plate currents of 
the two 6AG5 RF amplifier stages and this current, in turn, is a function of 
the AGC voltage applied to these tubes.   In common to most vacuum tube 
receivers the AGC system involves high impedances so the first thing to check would 
be the capacitors involved for leakage and the resistors for changes in their 
original values.   Since you report your set has been recapped I would 
concentrate the resistors here, R8, 11, 41, 42 & 88.   Note that R11 (5.6 meg) and 
R88 (2.2 meg) form a divider circuit through which a reduced AGC voltage is 
applied to grid of the first RF stage.   In my SX-42 I had to reduce R11 to 4.7 
meg and increase R88 to 5.6 meg to achieve appropriate S meter readings.

Hope this helps.

Dennis D. W7QHO (ex. DA1IN, G5BSW)
Glendale, CA