[Elecraft] K2 : Is this ok for AGC threshold??

[Don Wilhelm]

Fred,

It is all relative.  If the 8 volt regulator output is on the lower side 
of its spec (it is a 10% tolerance part), then everything will work out 
just fine, set it to the maximum.
Reason - the IF amplifier is the stage controlled by the AGC, *and* it 
is powered by the 8 volt regulator.  When the IF Amp supply voltage is 
reduced, the ACG action begins at a lower voltage point than at higher 
voltages.

Bottom line - if you are able to set the S-meter parameters with the 
lower AGC Threshold voltage, then all is well.  If you cannnot adjust 
the S-meter, then a 10k to 15k resistor soldered across pins 3 and 4 of 
Control Board RP6 will allow you to adjust the threshold upward.

Yes, a manual errata sheet should be published IMHO.  The 3.8 volts is 
not graven in stone.  There is an implication in the K2 manual that the 
AGC threshold can be optimized later on, but there are no details of how 
to do that - in fact, that optimization is simply reducing the AGC 
Threshold voltage so that receiver noise does not activate the AGC.

73,
Don W3FPR

Fred Bennett N9TA wrote:
>    Hi Gang
>
> Construction on my 3rd K2 is coming right along......BUT....I have a 
> question: I'm at page 48 of the manual where I am going through the 
> first power-up checks. I can't get the "AGC Threshold" voltage up to 3.8 
> Vdc as suggested. My new K2 tops out around 3.62 as measured with a 
> Square D WMM-23 digital multimeter. Is this something I should worry about??
>
>                          73....de....Fred  N9TA 
>                   K2 serial# 6705 under construction
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