Why do I owe you a six pack?
If you didn't spend all that money on towers, beams, and coax, you'd be able
to keep the equipment calibrated!
[mailto:firstname.lastname@example.org] On Behalf Of Jim Brown
Sent: Thursday, February 11, 2010 8:35 PM
To: Tower and HF antenna construction topics.
Subject: Re: [TowerTalk] Measuring Coax Loss
On Thu, 11 Feb 2010 19:59:11 -0500, Mike Besemer \(WM4B\) wrote:
>Okay... I'll accept your argument about S-meters because frankly it's not
>worth arguing about. 3 dB or 6 dB is still not a great deal of loss at HF.
>I doubt that most of us can hear 3 to 6 dB 99% of the time.
A dB or two can make the difference in a marginal circuit, whether it's
or 160M. More than once, while in search and pounce mode during a contest,
failed to make a contact with a weak station after several calls at 900
then made the Q by retuning the amp for full power. That's only 2 dB.
>I'm not sure what you call a 'long run' of coax', but I have a 125' run to
>my relay point plus the additional length to the individual feedpoints. Is
>that what you consider long?
That's a short run by some standards. There are guys with 500 ft runs! My
tribander is a 380 ft run to the top of the tower, and its 1/2-inch heliax.
>I agree that it's not good to WASTE dB's but I also would not spend a bunch
>of money for a couple dB... be it on an antenna or other components to
>reduce loss... not for a standard HF station anyway. I already qualified
>previous statement saying that it did not apply to microwave/weak signal
>work. The fact that you implied that some of us are not 'smart operators'
>is rather assumptive and could be considered by some as offensive. As for
>me, I just don't find it worth while to worry about what I consider
Offensive? I don't know you at all, but some of the smart operators I'm
about include some very competitive contesters and DXers -- K6XX, N6RO,
K3LR, W8JI, W4ZV, K9DX. These guys do not leave tenths of a dB laying
That's a part of what it takes to win contests (and working the weak ones,
>Comparing the MFJ to another measurement is useless unless the other
>instrument is traceable to a NIST standard, so your comment about comparing
>it to another measurement is invalid... that comparison is ONLY valid if
>of the instruments is of known accuracy. Comparing to another instrument
>like having two watches... you never know what time it is.
You owe me a six-pack! Make it Fat Tire. :)
>As for my qualifications to measure coax loss, I spent 24 years in the
>military working on avionics systems. I made literally hundreds (probably
>thousands) of loss measurements on systems that required precise (and I
>precise down to a gnats-a$$) loss measurements. Depending on the
>application, we used HP power meters, spectrum analyzers, VNA's, and
>other calibrated methods. These were applications that could result in
>loss-of-life if done improperly. By that standard, a couple of dB on an HF
>station does NOT mean a hill of beans.
That's great if you HAVE all that test equipment, and if you have the budget
keep it calibrated.
>So, it's all a question of perspective. Before you impeach anybodies
>thoughts or qualifications again, you might want to think about that.
I think about it all the time, which is why I made the statements I did.
worked for many years in pro audio, and am a member of the Acoustical
Some of us know a LOT about the value meaning of a dB in terms of human
perception, and as K3ZXL noted, 1-2 dB can be quite obvious under certain
conditions. Like the conditions I cited in my first paragraph above.
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