Flex 6700 and 2MLDPA Power Adjustment

  • 1
  • Question
  • Updated 1 year ago
  • Answered
I managed to get a 2MLDPA working with my Flex 6700 this evening.  Works great but the max 2M power output is only 50 watts and I'd like to get its claimed 75 watts output.  Checking the manual it says the Inverter Port defaults to 0 dBm, but has the capability of up to +8 dBm.  I've attempted to change the Inverter output to +8 dBm via the Settings->Radio Setup -> XVTR window but it makes no difference in the output of the 2MLDPA. (Measuring equipment: Bird 43, 100w VHF slug & Bird Dummy Load).  Is there something I'm missing?
Photo of KF4HR

KF4HR

  • 827 Posts
  • 274 Reply Likes

Posted 1 year ago

  • 1
Photo of Brian Morgan VK7RR/4

Brian Morgan VK7RR/4

  • 81 Posts
  • 19 Reply Likes
This might be stating the obvious but check your power supply on full load on your 6700. It may be dropping sufficiently to limit your power out to the 50 watts.
Photo of WX7Y

WX7Y

  • 797 Posts
  • 164 Reply Likes
The Power amp is not in the 6700 here, you want to check the voltage on the 2MLDPA during transmit.
My 2MLDPA put's out 81 Watts with a input voltage of 14.5 Volts at 144.250 MHz. 
73's
Bret
WX7Y
Photo of Rick - W5FCX

Rick - W5FCX

  • 287 Posts
  • 77 Reply Likes
You should be able to vary the 6700 xvtr output level from -10 to +10 dBm. Agree with other posts to verify voltage and current to amp (xvtr) is holding up as expected. I’m using separate 12V supplies for 6700/xvtr and 160 watt amp, which works well for me.
(Edited)
Photo of KF4HR

KF4HR

  • 827 Posts
  • 274 Reply Likes
I adjusted my power supply voltages up a bit and it helped the power output of my 2MLDPA some.  My Flex 6700 is now running at 14.0vdc in receive mode and 13.8vdc with 100 watts key down (on HF frequencies).  I use a separate Astron 35 amp linear supply for my 2MLDPA which indicates 14.4vdc in receive and 14.0 vdc full power output, which is now producing 62 watts.  Does this 2MLDPA power level seem normal for these voltage input levels?

One thing that bothers me is no matter what I change the Max Power (dBm) setting to in the SSDR XVTR window, it makes no difference at all in my output power of my 2MLDPA.  I can change the Max Power (dBm) setting from +8.0 to 0.0 to -8.0 and it doesn't change the output of the 2MLDPA at all.  I think I might have some syntax incorrect in one of these XVTR field settings.   My settings currently show:
Name: 2  (the word Valid is in green)
RF Freq (Mhz): 146.000IF Freq (Mhz): 146.000LO Freq (Mhz): 0LO Error (Hz): 0Max Power (dBm): +8.0
Does any of these settings look incorrect?
(Edited)
Photo of WX7Y

WX7Y

  • 797 Posts
  • 164 Reply Likes
Mine works just fine using the Normal "RF Power" and "Tune PWR" sliders, no need to go into the XVTR Power control from "0" to "81" watts out just like the rest of the bands works 0 to 100%. 

I have NO settings at all in the "XVTR" setup as the 2MLDPA does NOT need them, maybe this is your issue. 

hope you get it figured out 
Bret
WX7Y
Photo of Rick - W5FCX

Rick - W5FCX

  • 287 Posts
  • 77 Reply Likes
Ah. That’s right. The 6700 supports 2M without the transverter at all. Sounds like that could be it.
(Edited)
Photo of KF4HR

KF4HR

  • 827 Posts
  • 274 Reply Likes
Bret/Rick - Here's where I'm confused.  According to DEM directions for the 2MLDPA, the output of the XVTR port is connected to the 2MLDPA for drive.  And according to the Flex-6700 manual the XVTR output level has a default setting of 0 dBm or 1mw.  The 2MLDPA is designed for a drive level up to 10 mw (10 dBm).   Based on my input voltages above I'm getting 65 watts output max (8 out of 10 LED's on the 2MLDPA).  My thought is, if I could boost the 2M dBm level up slightly I'd be able to achieve full output my amp, but as I mentioned in a previous post, no matter what dBm entry I use, it does not change the XVTR output level, even though the Flex manual indicates it should.   

My RF POWER and TUNE sliders work fine adjusting the 2MLDPA output level between 0 and 65 watts, but that's it.  I'm curious if anyone is able to vary their XVTR dBm output level in SSDR -> Settings -> Radio Setup -> XVTR tab -> using the Max Power (dBm) entry?
At this point I'm not sure if my 2MLDPA may have a defect which is producing low output, or the XVTR Port on my Flex 6700 may have a low drive level (I have no way of measuring mw levels), or if there's a way to boost the XVTR output which I'm not seeing.
(Edited)
Photo of Rick - W5FCX

Rick - W5FCX

  • 287 Posts
  • 77 Reply Likes
Good question. What does Down East Microwave support suggest?

Either the Flex isn’t outputting 10 dBm when xvtr isn’t set to 10.0 or the XVTR output isn’t amplified as expected. Could be any number of things and you need a way to isolate which one it is.
Photo of WX7Y

WX7Y

  • 797 Posts
  • 164 Reply Likes
The 2MLDPA is NOT a XVTR but rather just a Power Amp, the 6700 has 2 Meters out  when you select the 2 Meter band button!

Some questions

What Frequency?
What is your Power meter?
What Antenna or dummy load?
What's your SWR? 
Cable length and type between the 2MLDPA and power meter?
Voltage right at AMP (not power supply) when transmitting at hi power

These are all variables that could effect your readings.
your only loosing about 1 db from what mine reads here. 

Maybe I can duplicate this BUT THE XVTR settings is the wrong place to change the power out, they are preset in the radio firmware when you use the "2M"  selection under the Band selections. 

They should work under the XVTR "Band" select button though. 

73's
Bret
WX7Y
Photo of KF4HR

KF4HR

  • 827 Posts
  • 274 Reply Likes
Hi Bret - Yes, I'm aware the 2MLDPA is an Amplifier, but it is using the XVTR port to drive this Amp, which when the 2M slice and XVTR port is selected, seems like a dBm drive adjustment would be available (via the XVTR Max Power (dBm) setting).  Evidently there must be some way to increase or decrease this drive adjustment or the DEM manual wouldn't be cautioning against over driving (ten bars) it with the 6700.

What Frequency?  146.000
What is your Power meter?  Bird 43 with 100 watt VHF slug
What Antenna or dummy load?  Bird 100 Dummy Load
What's your SWR?  1:1
Cable length and type between the 2MLDPA and power meter? ~7 feet
Voltage right at AMP (not power supply) when transmitting at hi power. 14vdc
Photo of WX7Y

WX7Y

  • 797 Posts
  • 164 Reply Likes
I think the Manual from Down East was written BEFORE FLEX put 2Meters in the Band selection.
 As I stated in my first message on MY 6700 it adjusts with the Power Slider and Tune Power NO XVTR settings required,  just add it to the USB list and PLUG and PLAY for 81 Watts MAX out. 

If you can't get max out then you must have a problem in the radio or Amp. 

 Best to  do a FLEX trouble ticket and contact Q5 Signal  @   http://q5signal.com/index.php?route=product/category&path=65 who I think has taken over Down east for help and repair. 

good luck

Bret
Photo of Sergey, R5AU

Sergey, R5AU

  • 862 Posts
  • 117 Reply Likes
2m was at beginning with 6700 in the Band Selection.  :-)
I am using early design of 2MLDPA (before USB introduction), PSU is GSV-3000 for both Amp and 6700. Output at max  = ~ 100watt(but with used module and proper strong cooling possible to get much more). I  tuned Amp on 80watts with  0dbm out(with Amp dimmer) 
(Edited)
Photo of David-N5PSM

David-N5PSM

  • 173 Posts
  • 42 Reply Likes
No one is asking what frequency!!!!
   Check that you are in the Satellite band center and check power.  unless I am mistaken the full power is at the Satellite band center unless you requested something else from DEMI.

My station is down right now for antenna work, so if someone can verify this I would appreciate correction if I am wrong.
Photo of KF4HR

KF4HR

  • 827 Posts
  • 274 Reply Likes
Official Response
Problem solved.  A RG-8x faulty coax jumper was the culprit.  My 2MLDPA is putting out 80 watts now.  Thanks for all the comments. 

This conversation is no longer open for comments or replies.