Re: Samlex 1223 & 1235 power supplies

I use the Samlex SEC 1223 power supply for my K3/100 and the Samlex SEC 1235
to power my Ten Tec OMNI Vll transceivers.
 
Both power supplies are dead quiet, the fans seldom come on. They both sit
on top of the transceivers and never cause sperious
interference.
 
Phil I would highly recommend these units. Less than $110.00 for the 1223
unit,
 
73,  Bob  VE3XM
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John & Phil,
 
I use a SEC1223 power supply with my K3/100. It sits on top of the K3. Never
the least bit of hash or fan noise experienced.
 
Highly recommended!  I also use the SEC 1235 with my Ten Tec OMNI VII same
experience.
 
73,Bob  VE3XM
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[Bill Coleman-2]

On May 23, 2010, at 6:12 PM, abell wrote:

> I use the Samlex SEC 1223 power supply for my K3/100 and the Samlex SEC 1235
> to power my Ten Tec OMNI Vll transceivers.

I use a SEC 1223 with my K2/100 and TS430S.

> Both power supplies are dead quiet, the fans seldom come on. They both sit
> on top of the transceivers and never cause sperious
> interference.

The SEC 1223 does generate some RF noise. This is most noticeable on 160m. It can be tamed with a little work. If you go to my review on eHam.net, you can see how I fixed the issue.

I've been using it for a couple of years now. For most use, it stays quiet. If you are running RTTY or CW with lots of CQs, you can get the fan to come on, and it is loud. It doesn't come on often enough for me to bother trying to fix it.


Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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[Jim Brown-10]

On Mon, 24 May 2010 07:57:25 -0400, Bill Coleman wrote:

>> Both power supplies are dead quiet, the fans seldom come on. They both sit
>> on top of the transceivers and never cause sperious
>> interference.

>The SEC 1223 does generate some RF noise. This is most noticeable on 160m.

It is important to understand that sitting on top of the transceivers is
NOT the primary interference coupling mechanism for RFI. Rather, noise is
coupled out of the noise source external wiring (that is, the AC power cord
and the DC power wiring), which then radiates it INTO YOUR RX ANTENNA. Noise
sources can also radiate from INTERNAL wiring if they are poorly shielded,
again picked up by your antenna. Physical proximity of the noise source to
your rig has nothing to do with this process. What matters is proximity to
your ANTENNA. Of course, if your antenna was a long wire that ends at the
shack, it would hear a noisy power supply quite well.

The only mechanism in which a noise source might couple by proximity to the
rig is MAGNETIC coupling between a current loop and a rig that lacks magnetic
shielding for its wiring. The K3 has poor magnetic shielding at AF, but is
better at HF.  

73,

Jim K9YC


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[P.B. Christensen]

> It is important to understand that sitting on top of the transceivers is
> NOT the primary interference coupling mechanism for RFI. Rather, noise is
> coupled out of the noise source external wiring (that is, the AC power
> cord
> and the DC power wiring), which then radiates it INTO YOUR RX ANTENNA.

Jim, that's probably the strongest coupling mechanism most of the time
although some receivers have poor shielding from the immediate environment
and noise coupling can occur from the SMPS to the receiver's front end.

An example of this is the IC-7800 and IC-7700.  There's a product review on
the web of the IC-7800 that boasts how the reviewer can hear many stations
without the need for an antenna!  It's written as if that was a positive
attribute of the receiver.  In fact, it only demonstrates how poorly the
front end is shielded between the preamp/mixer and the antenna ports.  When
I disconnect an antenna from a port, I want the Rx dead quiet -- not a band
loaded with signals.

Another disturbing attribute of the '7800 and '7700 is that harmonics from
its internal SMPS can be heard when the receiver is tuned from ~ 80 kHz
through 160m with decreasing amplitude as the receiver is tuned upwards.
Oddly, the noise increases as the antenna ports are deselected.  Granted,
the '7800/'7700 are not meant for listening down in the LW/MW bands, but
it's an indicator to me as to how poorly the power supply is integrated with
the rest of the transceiver.

Paul, W9AC
 

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[Jim Brown-10]

On Mon, 24 May 2010 13:05:03 -0400, Paul Christensen wrote:

>Jim, that's probably the strongest coupling mechanism most of the time
>although some receivers have poor shielding from the immediate environment
>and noise coupling can occur from the SMPS to the receiver's front end.

>An example of this is the IC-7800 and IC-7700.  There's a product review on
>the web of the IC-7800 that boasts how the reviewer can hear many stations
>without the need for an antenna!  It's written as if that was a positive
>attribute of the receiver.  In fact, it only demonstrates how poorly the
>front end is shielded between the preamp/mixer and the antenna ports.

HAH!  Very interesting.

>Another disturbing attribute of the '7800 and '7700 is that harmonics from
>its internal SMPS can be heard when the receiver is tuned from ~ 80 kHz
>through 160m with decreasing amplitude as the receiver is tuned upwards.
>Oddly, the noise increases as the antenna ports are deselected.

Yet another great feature of a $10K radio. :)

73,

Jim K9YC



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[Vic K2VCO]

On 5/24/2010 4:32 PM, Jim Brown wrote:
> On Mon, 24 May 2010 13:05:03 -0400, Paul Christensen wrote:

>> Another disturbing attribute of the '7800 and '7700 is that harmonics from
>> its internal SMPS can be heard when the receiver is tuned from ~ 80 kHz
>> through 160m with decreasing amplitude as the receiver is tuned upwards.
>> Oddly, the noise increases as the antenna ports are deselected.
>
> Yet another great feature of a $10K radio. :)

I had an IC-751 that did this. In those days I was naive about switching supplies, and I
could not figure out what the noise was. At one point I had to send it to ICOM for service
for another problem, and I asked them to please fix the noise. They replaced a number of
parts (not connected with the PS) and reported it fixed. Of course there was no difference.

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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