[Elecraft] In Line Power Pole Fuses

[Rick NK7I]

25 amp fusing isn’t a lot over overhead for a K3 with KRX3, KIO3a, P3 with the SVGA board and the PR6-10 preamp in play. 

It all adds up.  Use what is appropriate for your rig combination.  

73,
Rick NK7I

Email spiel Czech corruptions happen

> On Jul 21, 2021, at 10:33 PM, Ray <wa6vab at gmail.com> wrote:
> 
> 30 Amp   --- A little too High for me !
> I would use 25 Amp. 
> WA6VAB  Ray  K3
> 
> 
> From: Dave
> Sent: Wednesday, July 21, 2021 7:43 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] In Line Power Pole Fuses
> 
> 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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