The big problem is IR loss in the wire from the power supply to the radio,
not necessarily the "ampacity" of the wire. The longer and thinner the
wire, the more the voltage drop as the current increases. The voltage will
vary quite a bit, and during SSB operation can add to the transmit IMD.
Also, if you have marginal power supply voltage to begin with, any further
drop during transmit can cause some circuits in the radio to go "buggy",
which is why TT recommends running 13.8 VDC if possible.
I replaced the original cable on my Orion II with 4' of #10 which has very
low IR loss at 20 amps.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Stuart Rohre" <rohre@arlut.utexas.edu>
To: <geraldj@storm.weather.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Wednesday, June 06, 2007 5:14 PM
Subject: Re: [TenTec] Gauge of wire from power supply question?
> Jerry makes a good point. The AC ampacity of wires is not solely
> sufficient
> for DC, and is imperfect at longer lengths for AC drops. Consider the
> voltage is rising and falling at the frequency of the AC potential, while
> the DC is heating the wire continuously while in use.
>
> I have noticed Kenwood is more generous with their size of cables than
> some
> manufacturers. Most hams probably at some point have to custom make their
> cables for mobile or home applications, so I simply am advocating a
> conservative cable sizing for ham transceivers.
>
> -Stuart
> K5KVH
>
>
> _______________________________________________
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> TenTec@contesting.com
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>
>
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