Low Power Output? 6300 or 6500

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  • Updated 3 years ago
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With  both my 6300 and 6500 they struggle to produce over 85 watts. 
Using the same DC supply and watt meter my other rigs easily do 100 watts. 
So am I the only one or have others noticed this?

I'm not interested in how small the DB difference is either. I just want to know.
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Steve N4LQ

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Posted 4 years ago

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KY6LA - Howard, Elmer

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So you have proven it's the power supply/cord/connector issue..  Not the radio

If you are still determined to get exactly 100W you can raise your supply voltage to 14.2V and that should get you 100W.
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Steve N4LQ

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Just the opposite. Any radio I've ever had has produced 100 watts or more with much longer and smaller gauge cable and less DC voltage. I have no urge to crank up the voltage any higher.
Being determined to get 100 watts is not a negative on my part either. 

So here's the "out" for Flex:

Transmitter Specifications
  • RF Output Power:  1-100W nominal SSB, CW, FM, RTTY, Digital; 1-25W nominal AM


Websters: 
NOMINAL

Existing as something in name only : not actual or real

: very small in amount

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Jim Gilliam

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I have to admit you are right. Nominal is a very vague term and really has no place in an engineering spec. Good point.


JIm, k6QE

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k3Tim

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Nominal....  I don't know...  NASA used that all the time in the Mercury  / Gemini / Apollio programs.  As in "O2 is nominal", trajectory "nominal"

I haven't found the formula but knowing power = V^2 / R where R is in ohms.  It would seem power is very dependent on voltage.

hold on, checked the ARRL Handbook (2014) and see an RF amp  with 250Watts OUTPUT using a pair of VRF151 MosFets in class AB @ 48 Volts.  The broadband match is 4:1.   So we have V = 48 volts and R=50/4 = 12.5 
V^2 / R =   48 x 48 / 12.5 = 184 Watts   * 2 devices = 368W *  0.70 percent efficient (class AB)  = 258 W
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KY6LA - Howard, Elmer

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As an Engineer I take exception to that comment "no place in an engineering spec"  

Heck REAL WORLD electronic components have all sorts of variations is specification.   Just look at the simple example of a resistor.. 68 Ohms  Plus or Minus (1% , 2%, 5%)...

Or listen to the Lunar Landing.. "Conditions Nominal"  
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Jim Gilliam

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You made my point!!! Why doesn't Flex say the same thing 100 Watts, +- 10%. Nominal could be plus or minus 99%!
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Steve N4LQ

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Copied from factory web sites. 
No mention of "nominal"

Kenwood TS-590sg 
HF Output Power100 W SSB/FM/CW/FSK, 25 W AM
------------------------------------------------------------------------
Elecraft K3
Output Power: 200 mW –100 W, ALC controlled (Reduced power on AM.)
----------------------------------------------------------------------------------
ICOM IC-718

Output power 2 - 100W SSB, CW, RTTY

------------------------------------------------------------------

Yaesu FT-950

60 - 6 meters, 100 Watts of Reliable Power 

  

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KY6LA - Howard, Elmer

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BTW.... Up to now I had never measured my 6700 Output Power as i usually run it at less than 20W or it will drive my 2K-FA well beyond legal limits...

So it was an interesting exercise to drag out several different digital wattmeters and compare the results...   I achieved Exactly 100W output with

an input voltage of 14.21 volts before the Fuse in the 6700 key up

and 13.68 volts before the Fuse in the 6700 key down

DDUTIL Readout was a constant 14.4Volts

SWR 1.06

Bottom Line .. I am losing 0.53V drop between my 50A Power Supply and 8 G cables...

BTW.. Powerpoles are definitely the standard connections for most EMCOMM Communications...   HRO sells powerpoles
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Ken - NM9P, Elmer

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So does west mountain engineering, and other suppliers that you will meet at hamfests. They are inexpensive and versatile. For the big rigs, get the 45 amp version rather than the 30 amp. They are compatible but accommodate a larger gauge of wire.
(Edited)
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Joe, KQ1Q

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I just re-tested my 6300 with 12 inch long 10 gauge DC power cables, and RF out going only through the LP-100A wattmeter then into a 50 ohm dummy load. I tested each band at 5 sec, 30 sec and 60 sec. I then waited 1 hr and repeated the test for 5 sec per band.

Flex 6300, RF Output Into 50 Ohm Dummy Load:

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k3Tim

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Joe,

Thanks for taking the time to gather this information and post it.  Informative.  The power didn't vary based on time, which is nice.
The DC pigtail had minimal loss no doubt.

Best Regards,,

k3Tim
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Scott N8UMW

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I see this is an old thread but must comment. It shows as being answered or resolved. I am a 6300 owner that does experience this problem. I have read all replies. I have tried a ten gauge short cable on my PS with no difference from the Flex supplied cable. I have full 100 watts on 20 and 10 meters. 85 to 90 at best on the other bands. This is both with the antennas and running short cables through a brand new Bird 43P to a dummy load with an Astron RS-70 PS at 13.73vdc with radio keyed at full power. I saw no change upgrading to the latest firmware/software. Am I correct in the assumption that I would have to send my radio back for a recalibration to get the power output it is rated to do? 
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DrTeeth

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That is similar to my findings (Flex 6300 here too), but my bands vary. You do realise that it is more likely that you will not get more power out, but just that the meter will read 100 on each band? That is my understanding of 'recalibration'. Just be happy that we can run 100% duty cycle modes at full power. If there actually is a slightly lower power out on a few bands it does not make any difference at the other end. I have much more faith in a meter that does not real bang-on 100W on every band anyway.

73 de Guy
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Tim - W4TME, Customer Experience Manager

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Testing power output on a complex impedance load (antenna) is not an accurate way to measure the power output of the PA.  It needs to be a resistive (dummy) load.  And you have to make sure you are delivering 13.8 VDC at the radio under load to the radio when transmitting to make full power too.

If you think you have a hardware issue, you should submit a HelpDesk support ticket.
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Scott N8UMW

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My load is a bird termaline and is resistive. No big deal. The extra ten to fifteen watts makes a bigger difference with the amp on and in restricted on antenna space so the extra power on the amp might make a little difference, but the radio works fine. Tim, are you saying seven tenths of a volt is going to make a ten to fifteen watt difference?
(Edited)
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DrTeeth

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@Scott

Good point about driving the amp.
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Tim - W4TME, Customer Experience Manager

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Scott - yes, possibly depending on the frequency.