[Elecraft] Using K3's Pre-amp

[Jay Bromley]

Hi Everyone,
I don't think this is out of line unless Dave is on CW mode using narrow 
BWs?  His setup is like mind, it is in the city and he has nearby neighbors. 
My antenna is a large inverted 75m Delta loop too low to the ground and I 
have S-3 to S-5 noise using 2.8 Khz BW with no pre-amp.  At 400 hz it drops 
down to S1.  Again pre-amp off.  Tons of noise here, but this is the 
quietest antenna I have used.  This was just checked on 40m tonight.

73 de jay/w5jay..

> Dave,
>
> Whether you need the preamp will depend on your antenna.
> Without involving any numbers, a quick test is to disconnect and then
> reconnect the antenna.  If the noise level increases when the antenna is
> connected, the radio has ample front end gain (in fact it may be too
> much - try it with the attenuator in too).
>
> Your noise level does seem very high, so as Wayne suggested, you may
> want to try a low gain directional receiving antenna should you want to
> work the weak ones.  There was one featured in QST for December 2008.
> Alternately, snoop out the neighborhood for the noise source and fix it
> if you can.
>
> 73,
> Don W3FPR
>
> Dave Yarnes wrote:
>> I'm just curious how others are using (or not using) the K3's pre-amp.  I
>> have found few, if any, situations where I felt the pre-amp really 
>> improved
>> a signal vs. the additional noise that is associated with turning on the
>> pre-amp.  It takes a lot of balancing, in my view, between the RF gain 
>> and
>> the AF gain to enhance a weaker signal, and I don't find the pre-amp to 
>> be
>> all that helpful.  Having said that, I'm pretty happy with the results I 
>> get
>> w/o using the pre-amp.  Also, signals on the K3 w/o pre-amp compare very
>> favorably to signals on my Orion II with the pre-amp on.  The K3 still 
>> seems
>> to hear just a tad bit better.  So, I'm wondering if I'm missing some 
>> other
>> trick or setting that would make the K3's pre-amp more beneficial.  I can
>> tell you that 90% or more of the time I tend to have my RF gain at 50% or
>> less (at about 12 o'clock), and make very slight adjustments of the RF 
>> gain
>> from there.  I suppose much of this might depend on one's noise floor.
>> FWIW, mine is about S4.
>>
>> Dave W7AQK
>>
>>
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