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[OT} Running a KX3 station from a holiday trailer

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Al Sather

[OT} Running a KX3 station from a holiday trailer

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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Bob N3MNT

Re: [OT} Running a KX3 station from a holiday trailer

I have run the exact same configuration from the TT battery with no issue. Pull power directly from the battery with both legs ( 12V and gnd) fused. I generally run about 40W as I have had little need to run more. You will need to monitor battery voltage so as not to pull the battery too low. I have not run from battery with power to the trailer as I expect some noise from the convertor. If I have shore power, I run from my switching supply.

Al Sather

Re: [OT} Running a KX3 station from a holiday trailer

In reply to this post by Al Sather

I should also add that I have approximately a 10 foot run of #8 wire
running from the batteries to the inside of the trailer, hoping I would
not have a significant voltage drop. This will terminate with a PP
distribution block. Total wire run should be less than 16 feet and
closer to 12 feet.
Al

On 7/31/2015 9:49 AM, Bill wrote:

> The issue from running direct to battery is voltage drop to your
> KX100. You need 13.8v minimum to get full power out of the KX100. I
> run my KX3 and 857D out of a class B Sprinter and have had to resort
> to a power supply run from shore power (or my Honda 2KW) generator to
> get really clean power at adequate voltage levels. I have a direct
> line from my PP distribution block to my batteries, but the batteries
> will not power either rig at full output power.
>
> Bill k4yjj
>
> On Fri, Jul 31, 2015 at 12:35 PM, Al Sather <[hidden email]
> <mailto:[hidden email]>> 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
> ______________________________________________________________
> Elecraft mailing list
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Jim Brown-10

Re: [OT} Running a KX3 station from a holiday trailer

In reply to this post by Al Sather

On Fri,7/31/2015 9:35 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.

Great generator, lots of them in our club. There's a fix for the noise.

http://nccc.cc/pdf/CQP-RFI2013-2.pdf addresses this and a lot of other
noise sources.

> 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.

Since 2004, I've been running all my gear on big 12V deep discharge
batteries that I "float charge" with a regulated supply set for about 14
VDC.

I've never found the need for any protection in line with the gear. We
do the same on FD, except that we use solar panels to charge the battery.

One thing I have run into with a K3 running from the 12V system in my
2006 Toyota Sequoia (big SUV). I was operating 6M with the motor off,
and decided to start it. That somehow interrupted power to the K3 for a
few seconds, which caused a microprocessor to lose its place. To get it
going, I had to remove it from the 12V line and let it sit for a while
(10-15 minutes).

The K3 doesn't like its power to be interrupted. The root cause of the
problem is that when you turn a K3 off using the front panel, it writes
its current operating conditions to RAM. When you interrupt power with
the K3 running, it can't do that.

I don't know how this might relate to the KX3.

73, Jim K9YC

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Elecraft mailing list

Re: [OT} Running a KX3 station from a holiday trailer

Interesting question. I run the KX3 mobile and find no such problem in my 2006 GMC durimax diesel. Could be the dual batteries take the load OK. Having said that I did a different approach for a friend for his field day work. He was having problems with people changing power leads and making short power outages. I put a super cap on the KX3 with a series Hot carrier diode. That seemed to take care of any short time interruption in the DC power. Will not solve the real disconnect long term.

Just another input.
Mel, K6KBE
From: Jim Brown <[hidden email]>
To: [hidden email]
Sent: Friday, July 31, 2015 10:16 AM
Subject: Re: [Elecraft] [OT} Running a KX3 station from a holiday trailer

On Fri,7/31/2015 9:35 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.

Great generator, lots of them in our club. There's a fix for the noise.

http://nccc.cc/pdf/CQP-RFI2013-2.pdf addresses this and a lot of other
noise sources.

Bob McGraw - K4TAX

Re: [OT} Running a KX3 station from a holiday trailer

In reply to this post by Al Sather

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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>
>