[AMPS] Review: SGC PowerCube

[Gerry Smith]

This article is intended as a review of
the SGC SmartPowerCube (SG-500) and
dealing with personnel at SGC.

First, be aware, the `Cube is NOT 500
watts on all bands. With mobile supply
voltage slightly above 12.8 V., at
maximum current, the power degrades to
about 350 watts on 10 meters. Here are
my results:
Band     Power In     Power Out
80        45 watts    500 watts
20        60 watts    510 watts
10       105 watts    350 watts
I sent this data to SGC, their response
was, ". the SG-500 is rated at 500W with
14VDC input." Who has 14 volts in their
mobile at 80 amps, even with a second
battery? No mention of 14V requirement
in their brochure. So, lower your
expectations on the higher frequencies.

Dealing with the SGC company is an
ordeal, at best. They need,
desperately, training in customership!
Trying to get pre-buying questions
answered was agonizing. Questions like,
"Will the amp do QSK?", "What is the
cutoff temperature? (to determine if
their fan is necessary)", etc., went
unanswered or I had to recall and find
someone I could convince to talk with
me (avoid a guy name `Terry', if you
can). Even the people that answer the
phone apparently believe they have more
important things to do. I have spoken
to many other consumers of SGC products
and the consistent comments are
`arrogant' and `difficult'.

The choice of connectors for DC power
and control functions are poor. The DC
power terminates in a large Cinch
barrier strip. The strip will not
accept typical large, Stacon type,
crimp connectors. I had to go to a
electrical supply house and purchase
copper screw compression connectors.
The connector for the remote control
functions appears to be a subminature
of a Molex, but not one typically found
in your parts box or at Radio Shack,
nor does it have a tab or friction
locking arrangement to prevent
vibration woes. A major internal
connector has the same lack of a
positive locking mechanism. The PTT
keying line goes under a screw, fine,
but be sure and have a small
screwdriver no more than 2 inches in
length. `Connectorization' is just not
well thought out.

The circuit and construction design of
the `Cube is good, except as noted
above. Also, one other negative, is the
tie down (attach) method. The unit
comes with rubber feet and, if you want
to secure the unit, you must improvise
or buy their nylon strapping kit. I
scrounged some aircraft shock mounts,
after scratching what is left of my
hair.

The case is cast and well made. The
circuit design is also good as is the
various built in protections. The
protections are: VSWR, temperature,
current imbalance among the 8 output
transistors, under voltage. Kudos to
them, good protection to prevent
evaporation of the amp under faulty
conditions.

Operation is simple, turn it on. It
works. You should be aware they have a
input attenuator which switches in at
various input power levels, depending
on the input frequency. It allows, for
example, for the full output power of
an Icom 706 or you can turn the 706
power down and achieve the same result.
The point where the attenuator switches
varies wildly, for example:
Freq       Power
 3.5 MHz    45 watts
14.2 MHz    60 watts
28.5 MHz   105 watts

If you are planning on purchasing a
`Cube, I highly recommend you call SGC,
(800) 259-7331, first and request an
operating manual for the unit (it took
3 calls for me).

73, Gerry
W6TER


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