With that power supply, which has both good over voltage protection and
current limiting, adding fuses in the DC line will add resistance to the
line. Even being a small amount, it will affect voltage regulation from
no load to rated load at the radio. For this reason I do not
recommend adding fuses to the DC power cables.
I agree that all 100 watt transceivers should have their DC power leads
connected direct to the power supply terminals and not through any DC
distribution device. As a rule, receive load to 100 watt CW/key
closed transmit load, the voltage drop at the radio should be less than
0.5 volts.
73
Bob, K4TAX
Message: 19
Date: Wed, 21 Jul 2021 19:18:48 -0700
From: Peder Kittelson<[email protected]>
To:[email protected]
Subject: [Elecraft] In Line Power Pole Fuses
Message-ID:
<ca+0yfthz8cueqxb0kyowqs9zennv5lof8pgodan9cxapefu...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
I have fused my Elecraft radio equipment with inline power pole positive
and negative ATC car standard blade fuses.
I am now doing an audit of the fuses in my system to make sure they are
appropriate for the equipment they protect. I realize there are internal
fuses in many cases, I prefer doubling my protection with inline external
fuses as well.
I have not read or heard anyone discuss the appropriate amperage ratings of
fuses for my equipment or equipment in general. I would appreciate your
recommendations on fuse sizes for these, as well as general approaches.
Equipment and Specifications from Elecraft Manuals:
1. Elecraft K3s with 100 watt amp: Specs are 17-22 amps typical on
transmit, recommended 25 amp power supply.
2. Elecraft KPA 500: Specs are PA Current 20 amp maximum.
3. Elecraft KX3: Specs are 1-2 amp typical current in transmit.
One other important question. I have conquered much of the RFI in my radio
room using power poles with extended thick Red and Black wiring wound
around toroids. In this case the leads go from the Astron RS-35A to the
K3s. I want to make sure there isn't too much drop in voltage over the
extended toroid wiring. How can I best gauge what the K3s receives in this
setup? The manual says it should receive 13.8 volts nominal, 11 volts
minimum and 15 volts maximum. I think I am beyond the provided and
recommended 5' power cable. I have not had any problems (that I know of).
I do not have a desk full of electronic devices for evaluating this, so is
there a simple way to be reasonably sure?
73 and thanks for your help,
W7RPK, Peder
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