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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