[Top] [All Lists]

[TowerTalk] Re: [losses]

To: <>
Subject: [TowerTalk] Re: [losses]
From: gdaught6@leland.Stanford.EDU (George T. Daughters)
Date: Tue, 16 Nov 1999 10:11:01 +0008

In the discussion of line and tuner losses, Ward wrote...

> 30% sounds like a lot, but it's only 1.55 dB.  Not to be ignored, by any
> means, but not a brutal signal reduction.  0.5 dB is about 10% signal
> loss.

It seems we often get fooled by such things.  I remember acquiring a 
bunch of old but apparently good RG8 coax.  Before I ran it "up the 
tower" I decided to test it at 29MHz.  I put a dummy load on one end, 
and my Bird 43 and transceiver on the other end.  I sent 100W down 
the line (I couldn't measure any Watts coming back).  Then I moved 
the Bird to the dummy load end, and keyed up.  Only 85 watts were 
making it down there! "That's a fifteen percent loss!  This stuff is 
junk!"  I then checked the manufacturer's specifications... the coax 
was in spec. for NEW cable!

Fifteen percent = about 0.7 db loss for however many feet I had.  
Gee, 0.7 db doesn't sound like as much as 15%!

George T. Daughters, K6GT

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>