Elecraft

Issue 12 re Astron Power Supply

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john@kk9a.com

Issue 12 re Astron Power Supply

I believe that the transceiver will operate below 11 volts but it is better
to keep it in the higher part of the voltage range. My power supplies are
all 13.8v and I use heavier cables than Elecraft supplied which keeps it
around 13.5v while transmitting.

John KK9A

Buck - K4IA wrote:

What is the minimum recommended voltage for the K3S? Using the stock
Elecraft 5' cable, I drop from 13.3 to 12.7 volts on key down.

Buck, k4ia
Honor Roll
8BDXCC
EasyWayHamBooks.com

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N8LP

Re: Issue 12 re Astron Power Supply

I think you'll find that many of today's transceivers DO NOT have a low
resistance connection between the negative supply lead and chassis.

Larry N8LP

On 4/17/2018 5:37 PM, [hidden email] wrote:

> Message: 10
> Date: Mon, 16 Apr 2018 22:39:44 -0700
> From: Alan<[hidden email]>
> To:[hidden email]
> Subject: Re: [Elecraft] Issue 12 re Astron Power Supply
> Message-ID:<[hidden email]>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> You're right. If all the devices run from the same 12V power supply and
> they are all bonded together, then there is nothing to prevent some of
> the transceiver return current flowing in the negative power supply
> leads of the other devices. Hopefully the transceiver power leads use
> much heavier wire so most of the current will flow in them. And if the
> plus and minus leads are close together and tightly twisted then that
> should reduce hum and noise coupling.
>
> Ideally every device would have its own 12V power supply, each with
> floating ground. Then there would be no "ground loop". (Sorry Jim, I
> know you don't like that term.)
>
> Alan N1AL
>
>
> On 04/16/2018 10:22 PM, Vic Rosenthal wrote:
>> But I keep coming back to this: almost every device connected to the power supply has V- connected to ground internally. So if you have, say, a keyer and a transceiver running off the same supply, won?t some of the transceiver?s current flow through the V- line to the keyer, to the case of the keyer via the internal connection, to the station bonding, to the transceiver case and thence to the transceiver V- input?
>>
>> In short, don?t the accessories fed from the same PS as the transceiver do exactly the same thing as the notorious black wire in the Astron?
>>
>> Vic 4X6GP
>>
>>> On 16 Apr 2018, at 23:50, Jim Brown<[hidden email]> wrote:
>>>
>>> Joe is right and George is WRONG. V- is NOT GROUND, it is the return for DC power. Bonding V- to ground is a BAD idea -- that's why virtually all pro-grade power supplies are built either without the bond or so that the bond can easily be removed.
>>>
>>> As to those who were confused by my advice -- I thought it was pretty plain.
>>>
>>> Quite a few posts back, I posted a link to a detailed discussion of this on my website. I published this around 2010-12. I urge those who are confused to study it.
>>>
>>> http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf
>>>
>>> My detailed advice on station grounding and bonding is the link below. Much of it has been incorporated in Ward Silver's recent ARRL book on the topic, and is referenced in the book. You can buy the book from ARRL, while the pdf on my website is free. :) Joe and Don are right on in their understanding of the NEC, the fundamentals of which I have been paid to teach to audio/video professionals in workshops at conventions.
>>>
>>> http://k9yc.com/GroundingAndAudio.pdf
>>>
>>> 73, Jim K9YC
>>>
>>>> On 4/16/2018 7:06 AM, Joe Subich, W4TV wrote:
>>>>
>>>> On 2018-04-16 9:28 AM, George Danner wrote:
>>>>> Re-Connect it!
>>>> DON'T CONNECT THAT WIRE BETWEEN V- AND CHASSIS CASE!
>>>>
>>>> Unless you have a substantial*EXTERNAL GROUND CONNECTION*
>>>> between your station ground and the electrical system ground
>>>> rod, that connection between V- and chassis will bridge the
>>>> power system "safety" ground and the station grounding and
>>>> put your delicate and expensive equipment between two "grounds"
>>>> that can separate by many hundreds of volts in a lightning
>>>> event (or equipment failure).
>>>>
>>>>> We even used ring grounds around studio & transmitter building with
>>>>> ground rods every 10' all cad-welded.
>>>> That is proper grounding and bonds all entry points together*OUTSIDE*
>>>> the building to prevent grounds from separating. It creates a common
>>>> "island" for everything inside the building. However, for the majority
>>>> of amateur stations which fail to properly bond the shields of all of
>>>> the coaxial cables entering the shack to the electrical system ground
>>>> *at the meter*, there is no "island" ... more like an isthmus across
>>>> the equipment.
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>>> On 2018-04-16 9:28 AM, George Danner wrote:
>>>>> Re-Connect it!
>>>>>
>>>>>> From a broadcaster (AM,FM & TV) was in South Florida (lightning capital of
>>>>> North America).
>>>>>
>>>>> The more massive the common (ground, bonding, whatever term you use) for the connection between equipment and the power company ground connection the better.
>>>>> We even used ring grounds around studio & transmitter building with ground rods every 10' all cad-welded. This is probably over kill for a ham station; but think as massive as you can.
>>>>> Towers at 500' or above had 2 ring grounds and lots of ground rods.
>>>>>
>>>>> The common for equipment interconnection is for safety first and the reduction of voltage drops on the common lines that can transfer from one piece of equipment to another (us old timers use the term ground loop - not PC any more).
>>>>>
>>>>> 73 George AI4VZ
>>>>>
>>>>> -----Original Message----- From: Charlie T
>>>>>
>>>>> "This greatly increases the chances for damages to station equipment and all other electronic equipment in the household in event of a lightning event."
>>>>>
>>>>> What is, disconnecting the wire or leaving it in place?
>>>>> Your comment can be taken both ways.
>>>>>
>>>>> 73, Charlie k3ICH
>>>>>
>>>>>
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Bob-270

Re: Issue 12 re Astron Power Supply

In reply to this post by john@kk9a.com

I think the original question has morphed. It is really two questions. The
operational range of the K3 as one. The second is really the optimum range of
the K3. In dealing with the drops between the K3 and power supply how much is
excessive? My Astron is set for 14 volt and drops at the K3 under XMIT. How
much drop would be necessary for the IMD to rise to an unacceptable level? Or
put another way what is a reasonable goal for the drop in the power cable or
power distribution to the K3?

Zero millivolts would be ideal but not obtainable. I'll admit to not having the
knowledge or test gear to measure the IMD. If instead of getting 100 watts I
could only get 95 watts to me that would be insignificant. But I don't want to
XMIT a "dirty" signal either.

73,
Bob
K2TK ex KN2TKR (1956) & K2TKR

On 4/17/2018 7:55 PM, [hidden email] wrote:

> I believe that the transceiver will operate below 11 volts but it is better
> to keep it in the higher part of the voltage range. My power supplies are
> all 13.8v and I use heavier cables than Elecraft supplied which keeps it
> around 13.5v while transmitting.
>
> John KK9A
>
>
> Buck - K4IA wrote:
>
>
> What is the minimum recommended voltage for the K3S? Using the stock
> Elecraft 5' cable, I drop from 13.3 to 12.7 volts on key down.
>
> Buck, k4ia
> Honor Roll
> 8BDXCC
> EasyWayHamBooks.com
>

Wes Stewart-2

Re: Issue 12 re Astron Power Supply

Unfortunately, the IMD can be unacceptable even with the supply set to the high
side.

I will confess to not having measured IMD v. supply voltage. For my manual
method, that entails another layer of data. I have however, characterized my
old K3 and my new K3S with three different LPAs and four HPAs, with frequency
and output power as variables. I suspect that most would be surprised to know
that there is significant variation over frequency; more than with respect to
power.

My K3s in its latest reincarnation KLPA3A Rev B3, KPA3A Rev C9, has exceptional
IMD of -42 dBc at 40 meters and unacceptable IMD of -22 dBc at 10 meters and 10
W output. Same radio, power supply and measurement system. The only variable:
frequency.

Wes N7WS

On 4/17/2018 6:31 PM, Bob wrote:

> I think the original question has morphed. It is really two questions. The
> operational range of the K3 as one. The second is really the optimum range of
> the K3. In dealing with the drops between the K3 and power supply how much is
> excessive? My Astron is set for 14 volt and drops at the K3 under XMIT. How
> much drop would be necessary for the IMD to rise to an unacceptable level? Or
> put another way what is a reasonable goal for the drop in the power cable or
> power distribution to the K3?
>
> Zero millivolts would be ideal but not obtainable. I'll admit to not having
> the knowledge or test gear to measure the IMD. If instead of getting 100 watts
> I could only get 95 watts to me that would be insignificant. But I don't want
> to XMIT a "dirty" signal either.
>
> 73,
> Bob
> K2TK ex KN2TKR (1956) & K2TKR