[Amps] SG-500 and N8XJK Super Booster

[Arthur Movius]

Take a look at /Go mobile at 500 watts-SGC /on the web. It gives lots of 
good info.  I followed the recommendations, including the recommended 
Smart Relay and have run 500 watts mobile since 1999 without any hiccups 
with my SG500.  I have also used this amp powered by a 100 amp-hr deep 
cycle RV battery with 12" large battery leads to the amp for 48 hours of 
SSB contesting using a 20 amp charger that was able to keep the battery 
voltage up with no loss of rated amp power output--nothing fancy, no 
caps, no battery booster.

I tried a MFJ switch mode power supply rated for the amp--it lasted less 
than 30 seconds.

73, Jim, K7AJM


On 9/11/2016 7:13 AM, Jim Thomson wrote:
> 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
>
>       
>
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