Astron VS-35M Powwer Supply V-

[Elecraft mailing list]

I have been working on bonding my station equipment and have come the issue of bonding/RFI fixes to the VS-35M. I have read that it is suggested to scrape the paint around the green wire from the ac round plug attachment point to the case. But there is also a small black wire that bonds the V- terminal to the case. Should the paint around that screw also be removed?  Does that negative rail need to be bonded to the chassis? 
73Paulkc2nyu
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[Jim Brown-10]

Hi Paul,

I'm probably the source of this, although W8JI and W4TV have also raised
this issue. See comments below.

On 4/10/2018 11:48 AM, paul ecker via Elecraft wrote:
> I have been working on bonding my station equipment and have come the issue of bonding/RFI fixes to the VS-35M. I have read that it is suggested to scrape the paint around the green wire from the ac round plug attachment point to the case.

Yes, VERY important.

> But there is also a small black wire that bonds the V- terminal to the case. Should the paint around that screw also be removed?

Yes, IF you want to bond V-.

>   Does that negative rail need to be bonded to the chassis?

No, and in general, it should NOT be bonded.

AND proper station bonding is quite important.

Study http://k9yc.com/GroundingAndAudio.pdf  and/or N0AX's new ARRL book
on the subject, which parallels my work. (My slide show pdf is free.) :)

73, Jim K9YC

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[Joe Subich, W4TV-4]

On 4/10/2018 3:21 PM, Jim Brown wrote:
 >
> I'm probably the source of this, although W8JI and W4TV have also
> raised this issue. See comments below.

 >>   Does that negative rail need to be bonded to the chassis?
 >
 > No, and in general, it should NOT be bonded.

You *DO NOT WANT* the station bonding ("ground") and the V- rail to
be interconnected.  If you allow that to happen, particularly at
the transceiver and power supply, the station ground becomes an
alternate return for the high current pulses during transmit.

When the station bonding is allowed to "float" with the high current
pulses any other accessory connected to the bonding (particularly
"linear" bonding) sees a varying ground reference level which
contributes to "RF feedback" as that varying reference "pumps"
(excites) any pin 1 problem in the device.

Keep all of the transmitter power supply return current confined to
the power cable between the rig and the power supply. Make sure all
power supply connections are tight and all power cords as short as
possible.  Always use the largest practical wire for all power cords.
If possible, use twisted pair cables, *bolted* connections (like
on the Astron RS/VS series power supplies) and multiple, parallel
pin connections in any power connectors.

73,

    ... Joe, W4TV


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[Bill Clarke]

Hi Joe,

You made a comment about "bolted" connections. I hope I understood you
correctly, as I now don't feel so bad about using old fashioned screw
terminal blocks for all DC power. I feel they provide solid, unmoving,
and permanent connections. I do not like the push on Power Poles, as I
flat do not trust them - too many failures. Many such from merely moving
a piece of equipment and slightly disturbing the wires. And, yes - I do
know how to put Power Pole connectors together properly.

Hence, with the exception of the required plugin on the K3 - I do not
use them any longer. That plugin has a fixed strain relief installed on
it - in case I move the rig a tenth of an inch.

Bonus: No expensive plugs or tools required!

Bill W2BLC K-Line


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[Vic Rosenthal]

But since there may be multiple devices connected to the power supply,
and most of them have the V- connected to the case, then in effect there
is a path to the radio through all of these connections.

How can you "Keep all of the transmitter power supply return current
confined to the power cable between the rig and the power supply" when
there is a path from the PS to the V- input of an accessory, through the
case of the accessory, back to the ground bus, to the case of the radio,
and from there to the V- input of the radio?

Wouldn't it REDUCE the change in the ground reference to bond the V- to
the bus?

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 11 Apr 2018 00:04, Joe Subich, W4TV wrote:

>
> On 4/10/2018 3:21 PM, Jim Brown wrote:
>  >
>> I'm probably the source of this, although W8JI and W4TV have also
>> raised this issue. See comments below.
>
>  >>   Does that negative rail need to be bonded to the chassis?
>  >
>  > No, and in general, it should NOT be bonded.
>
> You *DO NOT WANT* the station bonding ("ground") and the V- rail to
> be interconnected.  If you allow that to happen, particularly at
> the transceiver and power supply, the station ground becomes an
> alternate return for the high current pulses during transmit.
>
> When the station bonding is allowed to "float" with the high current
> pulses any other accessory connected to the bonding (particularly
> "linear" bonding) sees a varying ground reference level which
> contributes to "RF feedback" as that varying reference "pumps"
> (excites) any pin 1 problem in the device.
>
> Keep all of the transmitter power supply return current confined to
> the power cable between the rig and the power supply. Make sure all
> power supply connections are tight and all power cords as short as
> possible.  Always use the largest practical wire for all power cords.
> If possible, use twisted pair cables, *bolted* connections (like
> on the Astron RS/VS series power supplies) and multiple, parallel
> pin connections in any power connectors.
>
> 73,
>
>     ... Joe, W4TV
>
>
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[Joe Subich, W4TV-4]

> How can you "Keep all of the transmitter power supply return current
> confined to the power cable between the rig and the power supply"
> when there is a path from the PS to the V- input of an accessory,
> through the case of the accessory, back to the ground bus, to the
> case of the radio, and from there to the V- input of the radio?
Ohms Law!  If the transceiver power supply cable is short and heavy
guage with multiple contact pins (or #10 - 1/4" bolted terminals)
and #10 or 14" bolted terminals on the power supply, the impedance
of the desired path in the power supply cable will be much, much
less than the path through control cables (#16-#22 wires with
single small pins) and any accessories.

Elecraft/Astron come close with their power supply connection.  I
would appreciate it if the transceiver had bolted connections or
at least double up the power poles and move from #12 to #10 cable.
Doubling up on the power poles would allow using two (#12) cables
further reducing the impedance (and voltage drop) of the desired
path.

73,

    ... Joe, W4TV


On 2018-04-11 2:27 AM, Victor Rosenthal 4X6GP wrote:

> But since there may be multiple devices connected to the power supply,
> and most of them have the V- connected to the case, then in effect there
> is a path to the radio through all of these connections.
>
> How can you "Keep all of the transmitter power supply return current
> confined to the power cable between the rig and the power supply" when
> there is a path from the PS to the V- input of an accessory, through the
> case of the accessory, back to the ground bus, to the case of the radio,
> and from there to the V- input of the radio?
>
> Wouldn't it REDUCE the change in the ground reference to bond the V- to
> the bus?
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> http://www.qsl.net/k2vco/
> On 11 Apr 2018 00:04, Joe Subich, W4TV wrote:
>>
>> On 4/10/2018 3:21 PM, Jim Brown wrote:
>>  >
>>> I'm probably the source of this, although W8JI and W4TV have also
>>> raised this issue. See comments below.
>>
>>  >>   Does that negative rail need to be bonded to the chassis?
>>  >
>>  > No, and in general, it should NOT be bonded.
>>
>> You *DO NOT WANT* the station bonding ("ground") and the V- rail to
>> be interconnected.  If you allow that to happen, particularly at
>> the transceiver and power supply, the station ground becomes an
>> alternate return for the high current pulses during transmit.
>>
>> When the station bonding is allowed to "float" with the high current
>> pulses any other accessory connected to the bonding (particularly
>> "linear" bonding) sees a varying ground reference level which
>> contributes to "RF feedback" as that varying reference "pumps"
>> (excites) any pin 1 problem in the device.
>>
>> Keep all of the transmitter power supply return current confined to
>> the power cable between the rig and the power supply. Make sure all
>> power supply connections are tight and all power cords as short as
>> possible.  Always use the largest practical wire for all power cords.
>> If possible, use twisted pair cables, *bolted* connections (like
>> on the Astron RS/VS series power supplies) and multiple, parallel
>> pin connections in any power connectors.
>>
>> 73,
>>
>>     ... Joe, W4TV
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
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> ______________________________________________________________
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