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Re: [RFI] Quiet Power Supply?

To: jim@audiosystemsgroup.com
Subject: Re: [RFI] Quiet Power Supply?
From: Ken Winterling <wa2lbi@gmail.com>
Date: Wed, 3 Aug 2016 17:30:58 -0400
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Jim,

For pricing use your favorite search utility to find "iota power supply".
Mine was purchased off ebay.  I suspect they are not widely sold by ham
radio dealers because they aren't "pretty".  They do not have a nice case
for placing on a desk next to your gear, there are no meters, and no power
switch.  I have mine mounted under the desk directly below my HF gear.  It
is so quiet I forget it is there and powered on.

For reviews use your favorite search utility to find "iota power supply
review".  Before purchasing I didn't specifically search out EMC compliance
data but did look for RFI-related issues.  The only issue I found, at the
time, was RFI that interfered WITH the IOTA, not caused by it.  I purchased
mine quite a while after several acquaintances had good experiences with
theirs.   The DLS-55 is popular with Kenwood TS-480HX users since it can
handle the 40A required for the rig's 200W output.

My antenna farm is about 50 feet from the house.  My average noise level
fluctuates between S1-S2, not a scientific measurement, just a reference.
I hear nothing from the IOTA on any frequency where I have listened from
the AM broadcast band through UHF.  I do not have a spectrum analyzer so I
can't say with certainty it doesn't produce a signal(s) somewhere.  I can
only say that I, and any of my acquaintances who have purchased an IOTA,
have been pleased and report no discernible RFI.  Each QTH is unique, there
are no guarantee you will have the same experience.

Have you contacted IOTA Engineering and asked them to address your specific
concerns?  If not, their Technical Support can be reached at
1-855-363-9527.  Here is additional contact information for IOTA:
http://www.iotaengineering.com/whoswho.htm.

I have no connection with IOTA Engineering, I am just a satisfied customer
and wouldn't hesitate to purchase more of their power supplies.

Ken
WA2LBI


On Wed, Aug 3, 2016 at 3:18 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:

> On Wed,8/3/2016 11:29 AM, Ken Winterling wrote:
>
>> Check out the IOTA power supplies.  I have had the IOTA DLS-55 with IQ4
>> smart charger module for years.  Sometimes it has run 24/7 for months.
>> The
>> IOTA units are exceptionally RF clean and have excellent electrical
>> characteristics.
>>
>
> Hi Ken,
>
> I've scoured the IOTA website and cannot find a single word about EMC
> compliance, nor even about use with radio equipment. Their "technical
> library" is largely dedicated to the charging of lead-acid batteries. There
> are no prices on the website, and clicking on "Ham Radio/Hobby" in the
> Distributor link directs me to a company that specializes in sales to radio
> control users (we're talking battery charging for model airplanes here) and
> another that specializes in SELLING "TOP-OF-THE-LINE Chargers/Power
> Supplies/converters to Manufacturing and the Public," neither of which
> gives me a warm fuzzy feeling about RFI.
>
> Whether or not RFI will be observed from any noise source will strongly
> depend upon what "antennas" are connected to that noise source (AC wiring,
> DC wiring), the proximity of receiving antennas to the noise source, and
> the other RF noise present in the environment. Most hams have antennas that
> are pretty close to their shacks, and most of us have RF noise from other
> sources in the homes and businesses that surround us. I've seen far too
> many observations that XYZ product is clean when in reality it is not, or
> is quiet on some bands and not others, when in reality the noise it
> produces is covered up by other noise. As a result, I'm VERY skeptical of
> observations like this, especially when the mfr's published materials make
> no mention of RFI, when the product is not sold through ham distributors,
> and when the product is primarily used as a charger. :)
>
> All I can find in IOTA product literature is this statement: "The
> exceptionally clean DC output of the DLS Series converter promotes longer
> life for any connected load and virtually eliminates AC ripple that can
> cause static or premature failure of radio or television equipment." To
> most power supply designers, "ripple" means power-frequency variations in
> voltage, not RF noise.
>
> I've tried to use products like this that hams had claimed were "very
> quiet" and found that they were not. My QTH is quieter than most, but far
> from dead quiet, because I have neighbors. I've yet to find a switching
> power supply that is anything approaching quiet on 160M, or that is quiet
> enough to be run within 30 ft of HF antennas.
>
> So my question is, how quiet is your QTH, and how close are your antennas
> to your shack?
>
> 73, Jim K9YC
>
>
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