Re: [Paddlewise] VHF questions

Bob Denton wrote:
> 
> There is a lot of misinformation in Dan's post regarding antennas and
> batteries.

Well, one of us is confused (or possibly both). I will provide more
specifics this time to help others determine who it is that is providing
misinformation.  First, you write:

> 
> 1.      Alkalines produce MORE voltage then nicads although the curve is
> different. A radio that produces 5 watts with nicads may produce 7 or 8 with
> fresh alkalines. 

This is true if you are comparing, say, AA's to AA's, but that is not
relevant to my comparison of VHF alternatives.  Let me use a specific
example.  I have a radio (Icom M7) that has both a manufacturer-supplied
NiCad CM-89 battery pack (which does NOT use AA's) and a
manufacturer-supplied AA pack for use with alkalines.  The CM-89 pack is
rated at 9.6 volts, whereas 6 AA alkalines that fit in the
manufacturer-supplied AA holder produce 6 x 1.5volts for a total of 9.0
volts (when the alkalines are new) Of course it is less than 9.0 as the
voltage drops through use.  I asked Icom about the output of this radio
when used with alkalines (since they don't publish a figure) and they
said it would be LESS than 5 watts.  I think that they are correct.

>I've never heard the term "Energy Density"?

I have seen this referred to in varous references on battteries. One
place where have I seen this term is the Cadex Battery Book:

http://www.cadex.com/cfm/index.cfm?Pg=52&Lp=144&Db=&Mo=

Check out the section on "choice of batteries". It has a table with
"energy density" (measured in Wh/kg).  I did not make the term up. 


> 
> 2.      I don't know what type of telescoping antenna Dan is referring to,
> but the length of the antenna is not necessarily a key factor in determining
> the performance of the antenna. The small duckies tend to be inefficient but
> they are factory tuned for the frequency and radio they are designed for.  A
> telescoping whip would have to be accurately tuned for the operational
> frequency by extending it to the exact length, assuming it was long enough
> to function as a 1/4 wave. Other factors including the connector can affect
> the tuning. This would ideally be done using a field strength meter.

Suppliers of such antennas (including the marine electronics shop from
which I purchased mine) claim that a properly matched telescoping
antenna, mounted on the radio, can extend the range of a handheld
significantly.  You seem to claim otherwise.  I do not have the
expertise to tell who is correct as a matter of theory, so I must rely
on my own experiences, which suggest that the suppliers are correct.  Of
course this relies on a properly matched antenna.      

> 
> 3.      Today's nicads are almost memory free and don't require much
> coddling.

What you say disagrees with a major study by the Navy and GTE Government
Systems.  This study involved 3 ships and about 2100 batteries. They
found that a proper maintenance routine *greatly* improves performance
of NiCads.  There is a link to this study at the above Cadex site.  (Go
to the link entitled "GTE report".)  

I agree with your point about using test equipment to test your set-up. 
Any good marine electronics shop will have such equipment, and will be
willing to help you match an antenna to your radio to improve its
performance.

Dan Hagen
Bellingham, Washington
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