[Elecraft] K3 Power supply

[Erik N Basilier]

Merv,

My experience with the FT-1000D was that the S-meter didn't start to move 
until the actual signal strength reached S-5 or so. But yes, I believe you 
when you say that the switching power supply creates a lot of noise, and the 
one in the FT-1000D doesn't.

73,
Erik K7TV

----- Original Message ----- 
From: "Merv Schweigert" <k9fd at flex.com>
To: "Milt, N5IA" <n5ia at zia-connection.com>
Cc: <elecraft at mailman.qth.net>
Sent: Monday, May 11, 2009 4:14 PM
Subject: Re: [Elecraft] K3 Power supply


> Milt, N5IA wrote:
>>
>> ----- Original Message ----- From: "Merv Schweigert" <k9fd at flex.com>
>>
>>> I started to try and find the problem and using another
>>> receiver I find the Astron SS-30 is generating all sorts of noise.
>>> I have used this supply for some time and have not noticed the noise
>>> before.
>>
>> Merv,
>>
>> For weight considerations, the SS-30 supplies were selected for the
>> Ducie Island expedition this past year.
>>
>> This problem you mention, or a very similar one, was evident during
>> the VP6DX expedition from the time that Robin started making tests
>> while underway on the Braveheart from ZL to FO.
>>
>> We added extra filtering internally.
>>
>> We grounded extensively.
>>
>> We cleaned the case cover screw holes both on the main chassis and on
>> the cover to improve bonding to the cover.  We were never able to make
>> them clean.  All supplies performed in the exact same manner.
>>
>> We were float charging small batteries to keep the K-3s and the
>> ancillary equipment running while the gensets were being refueled and
>> having oil changed.  The extra capacitance of the battery helped with
>> the DC filtering but most of the stuff was of a frequency that the
>> battery and other filtering could not remove.  And we couldn't keep it
>> inside the case.
>>
>> The fact remains that the harmonics of the switcher were a very real
>> problem for us, especially on the lower frequency bands.  The most
>> annoying situation was the harmonic signal moving around, slowly up
>> and down the band such that we could not avoid it at times when we
>> were in the middle of a tough one on 160 and were trying to dig it out
>> of the noise floor.  We had to wait until the birdie slowly slithered
>> on by or many times I just reached and turned the SS-30 off during a
>> difficult contact.
>>
>> 73 de Milt, N5IA
> The noise floor with the switchers has always been a problem,  but the
> increase is what was
> bugging me, and happy to have it confirmed  that they are somewhat
> incurable,  thought it was just me,
> have done about all that Milt describes and still has noise.
> The past couple days its has just increased by 2 DB on the meter, in
> other words on 20 meters
> the K3 is hovering around s4 to s5 noise floor,  compared to turning off
> the switchers and K3
> and listening on a Ft-1000D it has a noise floor of S0.
> I guess its back to an old transformer supply,  had been trying to stay
> away from that due to the
> shipping weight etc.  Thanks for all the input.
> 73 Merv KH7C
>>
>>
>
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