[Elecraft] Astron VS-35M Powwer Supply V-

[Joe Subich, W4TV]

> 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
>>
>>
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