[Elecraft] In Line Power Pole Fuses

[Dave]

Hi,

I am unsure what you are asking...  If you are asking about fuse values, 
I select values a bit above the max peak current I expect.  For my K3 I 
use a 30 amp fuse.

If you are asking about voltage drop, and want to know what the K3 sees, 
there is a built in volt meter in the K3, (see the manual), which will 
show you the voltage at the K3, after all your fusing, and wiring.

I always take my voltage readings at full output.  I try and stay within 
the limits Elecraft sets for voltage.  If I am running low voltage on 
transmit, I goose the power supply slightly, staying below the max 
voltage rating Elecraft recommends when not transmitting at full power.

The fuse(s) is/are probably not going to protect my radio-- if something 
happens, (i.e., current draw in excess of 30 amps), the radio is 
probably already broken.

I use the fuse to reduce runaway thermal effects, (read that as fire), 
on my power supply wiring in the event of a short to ground.  I place 
the fuse(s) as close to the power supply as my wiring will allow.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 7/21/21 7:18 PM, Peder Kittelson wrote:
> 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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