KX3 external battery (Maxtron) VERY NOISY

[Robert Sands]

A reflector poster mentioned the Maxtron  MX 160A for use with the KX3. I
got one off Amazon and tried it. My noise level jumped from S4 to S9.Not
sure how to eliminate it.Nice otherwise.Transmit plug it in. Receive, pull
it out.
Robert E. Sands
K7VO
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[Dominic Baines-3]

Yeah it is an oxy moron sometimes... operate off grid using a battery
and you get noise (this will be the internal LiION battery
recharging/regulation circuitry causing it).

Have you tried adding ferrite to the DC leads (and weirdly to the
headset leads, I need to if using ext battery sometimes). You could make
up a simple choke and plug your rig power lead into that, doesn't need
to be in a box or anything... leads from battery then 12 turns of the
power leads or so in opposite directions in parallel on the ferrite (try
FT240-61) to a set of connections to the rig. Or a string of those
little 5mm ID clip on ferrites (ebay) on the Elecraft lead.

72

Dom
M1KTA
Owner of #1082 & #2334
On 06/03/15 04:53, Robert Sands wrote:
> A reflector poster mentioned the Maxtron  MX 160A for use with the KX3. I
> got one off Amazon and tried it. My noise level jumped from S4 to S9.Not
> sure how to eliminate it.Nice otherwise.Transmit plug it in. Receive, pull
> it out.
> Robert E. Sands
> K7VO

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[Bob N3MNT]

Yup.  It is not a 12 or 13.8V battery, but rather a low voltage source that has a switching circuit  ( aka noise) that generates the higher voltages,  These are designed to do as advertised and charge phones and tablets at relatively low current.  If you want battery operation, an SLA or LIFE battery is your best choice.

[Jim Brown-10]

On Fri,3/6/2015 12:43 AM, Dominic Baines wrote:
> Yeah it is an oxy moron sometimes... operate off grid using a battery
> and you get noise (this will be the internal LiION battery
> recharging/regulation circuitry causing it).

Probably so.

>
> Have you tried adding ferrite to the DC leads (and weirdly to the
> headset leads, I need to if using ext battery sometimes). You could
> make up a simple choke and plug your rig power lead into that, doesn't
> need to be in a box or anything... leads from battery then 12 turns of
> the power leads or so in opposite directions in parallel on the
> ferrite (try FT240-61) to a set of connections to the rig.

#61 is a VERY poor choice for suppressing noise at HF.  #31 and #43 are
the weapons of choice for the HF bands.

> Or a string of those little 5mm ID clip on ferrites (ebay) on the
> Elecraft lead.

Strings of beads or clip-ons are NOT effective at HF. Study

k9yc.com/RFI-Ham.pdf

73, Jim K9YC




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