[NLRS] preamps 222

[Gerald]

On Sun, 2005-12-18 at 00:48 -0600, Bruce Richardson wrote:
> 
> Hi Dave:
> 
> Oh, I may not have really answered your question.
> 
> For a portable/rover or frequently set-up situation I would NOT use a
> pre-amp either mast mounted OR in the shack (car).  Why?  Complexity.  If
> portable or frequently set-up, I would focus on the best feedline I could
> afford/handle (maybe LMR 600 instead of LMR 400).  And I would work on
> keeping feedlines short.  I had a pre-amp in my 1296 transverter/amp box
> and it got blown by the close proximity of the antennas on a rover.  So
> complexity and environment are two reasons to stay away from pre-amps in
> rover/portable/temporary set-ups.  There may be some differing views on
> this.
> 
> I've played with Mirage pre-maps (in the amp) and all they do is raise
> noise and signal.  When I was new, I had an ARR 2m RF sensed pre-amp that I
> put between the mirage brick and a TR-751 (which has an excellent
> reputation for ears).  I was in North Dakota at the time.  NT0V was the
> only other serious contester in the area.  He'd monitor me CQ'ing my lungs
> out from EN-17 or thereabouts.  One time, (maybe to get me stop CQ'ing
> :-) ) he did some minimum discernible signal tests with me.  He had test
> gear and could give me a REAL weak signal from his QTH about 40 miles away.
> He new about my ARR pre-amp.  So, the tests proved that I could not hear a
> weaker signal with the ARR preamp located between the amp and the TR-751.
> Had I had the pre-amp at the antenna feed--maybe.  What the ARR did was put
> the weakest signals I could hear from S0 to S3 or 4.  The TR-751 didn't
> need that kind of help :-) .
> 
> Whew!  That ought to be enough. Now let's see what the others think.
> 
> 73
> Bruce Richardson
> W9FZ
> 

Agreed. I've not yet found a signal I could copy better with preamp in
the shack on 2m and 70 cm (and keeping feed line loss low with hard
line) than without the preamp. With local packet, repeater, and TV
activity to clobber the receiver with the preamp gain, its probable that
a preamp will hide signals when turned on.


-- 
73, Jerry, K0CQ
Dr. Gerald N. Johnson, electrical engineer
All content copyright, Dr. Gerald N. Johnson