[Kenwood] TS-930S Piexx and W6NL P.S Mods

[Bill Tippett]

         I recently installed a used Piexx digital board in my
trusty 930.  I was planning to install W6NL's power supply
modification but asked Chris Sieg (Piexx designer) the
following question:

 > While I have you, I'm thinking of adding the 7808 and 7815 voltage
 > regulators to the power supply as described in W6NL's mods.  Rather
 > than mounting them where he did, I'm thinking of heat sinking to the
 > fan housing which will be much easier to do.  I believe the 7.5V and
 > 15V outputs only feed the digital board and am wondering if you know
 > approximately how much current they draw?

His response was:

Hi Bill,

 > The reason the mods you indicated were originally worth while is because
the old Digital Board in the TS-930 used linear voltage regulators. Excess
voltage, above the intended output voltage of a linear regulators, was shed
as heat, so the TS-930 power supply section pre-regulated the system 28 VDC
bus down to a lower voltage before it hit the linear regulators on the
digital board. This caused these linear regulator to dissipate less heat.
Our new TS-930SE digital board uses switching regulators (notice there are
no big heat sinks on it) so there is no reason to pre-regulate the 28VDC bus
for efficient use. Our board consumes less power as well. So, you really
don't need to do the mod.

-Chris
_____________________________
EMail <mailto:piexx at conknet.com>piexx at conknet.com
WEB <http://www.piexx.com>www.piexx.com

         The Piexx board is a wonderful addition for its added functionality
and a nice bonus is that it eliminates the need for the W6NL mod.  FYI
here is W6NL's complete mod article:

http://www.kkn.net/~k5tr/ts930fix/w6nl930.pdf

                                 73,  Bill  W4ZV

P.S.  W6NL must have misunderstood the Piexx design since he states:

"The regulators need capacitors near them, especially if they are 
driving the PIEXX board, which
has switching regulators with inductors at the input. The regulators 
should be prewired, and the
wires are connected to the voltage points inside the power supply fan case."

In fact, PIEXX's switching regulators obviate the need for his mod.