[Elecraft] [OT} Running a KX3 station from a holiday trailer

[Bob McGraw - K4TAX]

I use one of my 100 watt radios in our travel trailer.  I did run three 
lengths of #10 AWG automotive primary cable from the battery area to my 
operating position.  Both the DC negative and DC positive lines each 
have a 30A Fast Blow fuse located very close to the battery.  That third 
wire is a separate wire from the trailer ground, which is also near the 
battery to my operating position. This ground connects to the ground 
terminal on the radio.  I do not rely on DC Negative for ground.  
Otherwise, there is an equal DC drop on the Positive wire and the same  
also on the Negative wire, thus the radio is above ground by that 
amount.  Usually about 0.25 to 0.5 volts, depending on current.

The inverter supplying DC and charging the battery, which is normally 
associated with the trailer, does/did produce some hash. Several donuts 
with 5 to 8 turns of wire located in the inverter box greatly reduced 
the hash.  These were installed on the AC primary side of the inverter 
and the DC output of the inverter to the battery.   This took replacing 
some wires to get the added and needed lengths to add the ferrite 
filters.    I used RTV Silicone to hold each these in place thus 
preventing them moving when the trailer is in tow.   All is quiet now.

As to the Honda generator, the EI 2000 does produce some hash.  I just 
operate off of battery and don't operate when the Honda is running.  
While I haven't tried it, Jim, K9YC has good suggestions for filtering 
the AC line coming from the Honda.  In studying the topic, I would opt 
for putting the filter inside the Honda, if there is room.  Otherwise, 
locate it as close to the Honda output as possible.

73 Bob, K4TAX


On 7/31/2015 11:35 AM, Al Sather wrote:
> Greetings
>
> I know this is a bit of topic but I this this list has the expertise 
> to give me good answers.
>
> My station is a KX3-KXPA100 with a PX3. I have a quiet, to me, 30 amp 
> switching power and a 2000 watt Honda generator that generates some, 
> but not objectionable noise. The NB on the KX3 clears that up totally. 
> I also have a 20 amp liner Astron power supply but it is heavy, bulky 
> for use in a small trailer. And, it may be light for running an amp.
> I course I do not need to run it at 100 watts, either.
>
> I am trying to decide if it best to operate from the trailer's AC or 
> directly from the batteries.
> And, if I use the batteries alone are there precautions I need to take.
>
> Of course, if available I would use "shore power". The AC from the 
> trailer seems to be adequate when running with or without "shore 
> power" or with my generator.
>
> I guess my real concern is the issue of using DC directly, and what 
> should happen for protecton between my batteries and station.
>
> 73, Al ve7ear
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