[Elecraft] K3 and preamp

[Jim Brown]

On Fri,9/5/2014 9:59 AM, iain macdonnell - N6ML wrote:
> That doesn't justify a pre-amp. If you want more acoustic noise, just
> turn up the AF gain. The only reason (I can see) to use a preamp is if
> the receiver internal noise level is higher than the atmospheric noise
> (coming from the antenna).

Right.

> If the noise level perceptibly drops when
> you disconnect the antenna, a preamp isn't going to do much for
> you....

Perceptibly is not the right word if you care about weak signal work.  
The difference should be at least "twice as loud" when the antenna is 
added, which corresponds to about 10 dB.  Use the K3's internal audio 
voltmeter to determine this.  Turn off AGC, with the antenna connected, 
calibrate the dB readout to zero following the instructions in the 
manual, then remove the antenna.

73, Jim K9YC