Getting MEffa started

WC6Y

I have a new PGXL replacing my SPE FA1.5K which mysteriously lost its LDMOS overnight (not in use) the day before the CQ WW DX CW contest ...grr. I use a 6600, SmartSDR for Mac, an EFHW for 80 - 30m & a Spiderbeam for 20 - 10m. SWRs are all < 1.5 except for 12m which is 2:1 and the PGXL shows a power rollback to 1300w. Everything appears to be working great. Since I'm CW only, I thought I would engage MEffa. MEffa Enabled Box is checked under SSDR/Mac PGXL Settings panel, PGXL rebooted for it to take effect. Hit tune on 12m, shows 450w, SWR 1.8:1 on SSDR/Mac PGXL panel. Repeated tunes show no variation in Vdd and MEffa: 0.0% is displayed in the SSDR/Mac PGXL panel.

What am I overlooking?

Ken

David Decoons, wo2x

Hi Ken

MEffA works on single tone modes such as CW and FT8 but not on SSB. When MEffA is enabled you should see bias change from AAB to AB (except 6 and 160). Are he bias will drop from 4 amps to 2 amps. The idea of MEffA is the VDD voltage will vary with the impedance the amp sees to maximize the efficiency of the amp (less waste heat). MEffA will take more drive to give you full output due to the lower bias and lower VDD.

Since your SWR on 12 is a little high the complex impedance the amp is seeing may be out of range for the MEffA algorhythm.

are you only seeing this on one band?

73

Dave wo2x

Bill NE1B

Ken,

You said "Hit tune on 12m...". But you did not say you have an external tuner. Are you hitting the Tune button on the 6600...before the PGXL? Or do you have a Tuner Genius with the Tune button?

73,

Bill, NE1B

WC6Y

No external tuner. "Tune on 12m" is pressing the Tune button on SSDR/mac "Radio" panel. (see attached photo). Hitting "Tune" on 40m shows about 350w & 1:1 SWR. Again, no change in Vdd & MEffa still 0.0%. (Tuner Genius arrives next week). Curiously, hitting "Mox" on the same panel clicks the relay in PGXL but doesn't produce any power out.

bahillen

Two suggestions. Load FLEXmeter application and select TX Forward power. You will be able to monitor your 6600 drive power to your amp.

Second, I run multiple slices on different bands. Some times I get a brain freeze and the slice in focus is not the slice I thought I was on. The result is the SWR is not for the band I was expecting. Especially with the Tuner Genius eg, I think I have tuned on 20 m slice and really tuned on say the 40 m slice. You have to get in the habit of making sure the right slice is in focus and TX is also highlighted. Then hit the 6600 the 6600 tune button to see SWR, if not low enough hit the tune button the Tuner Genius.

I have wire antennas so rain and other things affect SWR. I am pretty cautious on not driving the PGXL into a high SWR condition due to my own error. I have also started to manually select the TX slice so the relays are not changed on every transmission.

just food for thought.

73

Bill

W9JJB

WC6Y

Thanks all for your insights. I too have had to be careful as to which slice has the "TX" illuminated and have transmitted on the wrong band before.

Here is some more description of the issue:

See attached screenshot showing the Radio Controls panel of the SmartSDR for Mac (SSDR/Mac) on the right side, overlaid by the additional SSDR/Mac window for the PGXL at the bottom. Tune Button was hit for on 10m. Starting at top right, tune power from 6600 is reported at 10w (and set just below that). SWR to PGXL is reported at 1.1:1. RF power is set to 49w (which generates 1500w from the PGXL) Note the 6600 ATU is bypassed. Hitting the Tune button also illuminated MOX.

Moving down, The "Power Genius XL" panel shows about 400w, SWR to the Spiderbeam at about 1.2:1. MEffa still at 0.0%

The window below "WC6Y PGXL" adds that PA current (Id) is 21A & PA voltage (Vdd) is 52v. Shows PTT engaged, 10w & class AB.

WC6Y

Reading under the PGXL Windows Utility front panel display section 9.4 (which I don't have since I'm Mac only) the manual describes a MEffa indicator above the PWR meter which you can click on and off. On the front panel of my PGXL this indicator is RED (as it is shown in the manual) leading me to suspect that it is turned off.

** For those of you out there using PGXL with MEffa, is your PGXL front panel MEffa indicator GREEN? **

I'm wondering if perhaps MEffa not working because it's not turned on. The PGXL front panel touch screen doesn't seem to be touch sensitive for this control.

WC6Y

Nope. MEffa enable is a checkbox in the SSDR/Mac PGXL Settings panel

David Decoons, wo2x

When you enable MEffA, does the bias change to 2 amps and VDD vary? How about under Windows?

Dave wo2x