[Amps] SG-500 and N8XJK Super Booster

[Jim Thomson]

Date: Fri, 09 Sep 2016 08:32:58 -0700
From: Larry Dighera <LDighera at att.net>
To: SGC-SmartPowerCube at yahoogroups.com
Cc: "amps at contesting.com" <amps at contesting.com>
Subject: [Amps] SG-500 and N8XJK Super Booster

Has anyone experience using the N8XJK Super Booster
<http://stores.tgelectronics.org/the-n8xjk-super-booster/> with an SG-500
linear amplifier?  The battery booster is rated at 40 amps and 16 volts
maximum.  

The SG-500 is rated for an input voltage of 14 VDC and an input range of 10 to
18VDC: <http://www.sgcworld.com/ampProductPage.html>.  Has anyone attempted to
run the SG-500 at 18VDC?  Can the booster do that without issues?  

Is the booster able to deal with the rapidly fluctuating 40 amp load the SG-500
creates during SSB output?  

What is the optimal location to connect a 2 farad smoothing capacitor, at the
SG-500's power terminals, or at the power input to the battery booster?
Intuitively, I would think the amplifier's power input would be best, but
thought it couldn't hurt to inquire.

Has anyone experienced timing issues between the booster's RF enable trigger
and the amplifier output?  

Best regards,
Larry
WB6BBB

##  The rapidly fluctuating ssb load will be  between  idle current...and  90+ amps. 
The average load will be 40A.   Any power supply will have to be able to handle 90+ amps on peaks. 
That booster device is only rated for 40A  CCS.... but you will be trying to suck 90A +  out of it
on peaks on ssb /cw.  They don’t state  a peak current rating for it.   Most dc to dc converters  wont handle
more than their rated CCS current.   Ditto with most switching supplies.   

##  is this for mobile use ?   Id suggest just using bigger ga cu wire, or 2 x big gauge wires in parallel,
to limit V drop.   The 2+  farad cap will work good though. You would think that a battery would be like a large 
cap, but they are not.   The ESR on a battery is a lot more than you think.   Those big 2+  farad caps are low ESR types. 

##  IF you locate the cap at the back of the amp, the cap has to be charged or topped up, between ssb /cw  peaks. 
So you want minimal V drops from amp to battery...IE: big gauge wireS.  IF you put the cap at the battery, then u
don’t have the problem with v drops between cap + battery.  But you still  need big gauge  wire to the amp. 

##  99% of most cars,  with engine on, you will see  14.4 vdc  right at the battery............  but typ only 12.2 vdc at the 
battery, with engine OFF. IE: alternators  will typ put out 14.4 vdc.    Newer alternators are of the 3 phase variety as of
about  2010+.    Alternators built in 2009 or prior use single phase. 

##  Those  unregulated DC  to regulated + higher DCV  units are common place in the hot rod world.   We use em to 
increase the loaded vdc  at the fuel pump, which is immersed in the gas tank.  The idea is to reduce the fuel pump duty cycle
by increasing the loaded vdc.  Typ they are installed in the trunk....AND  larger gauge wire also installed, back to the battery. 
Typ output of the unit is  a regulated 17 vdc..and most are of the 20 /40 A  variety.   But before we go that route, the fuel
pump duty cycle can be reduced 10-15% simply by increasing wire gauge. 

##  if u are using this for a mobile application, use bigger gauge wire.  Then add the  2 farad cap.   Your problems will start when
the engine is OFF, and you only have 12.2 vdc to start with..then it will drop from there..and fast with a 90+ A peak load. 

##  Some have used a 6 vdc  deep discharge golf cart battery, in series with a 8 vdc  deep discharge golf cart battery.... then at least
you have 14.4 vdc to begin with. 

##  You may well  be able to parallel  TWO or  three  of those battery booster units you linked to..if they divide the output current equally. 
But if just a normal sized car battery used, and eng off,   you are gonna suck it flat no matter what you do.   You also require a
135-160+ amp alternator to begin with. 

##  The 2+ farad caps   work good on car audio stuff.  Without the caps, the headlights will dim  with each bass thump.   

Jim  VE7RF