SSDR ver 3.3.29 SWR=1.4 on PGXL is always ON without any TX !

Sergey KN7K

With 6600,PGXL,TGXL, 2x8 reboot it may clear, but keeps coming back.

How come no Beta tester cough it?

NO TX, it is always shows about 1.4

Mike-VA3MW

This is a software bug and it will be fixed in the next PGXL firmware release.

AF3K

Mike,

Perhaps related to the SWR bug.....I ran into a slightly different PGXL metering issue after upgrading a 6700 to SmartSDR v3.3.29. After the upgrade there are no PGXL meter readings shown in the AMP panel within SmartSDR. (Meter readings do show in the PGXL and TGXL utilities.)

73,

John, AF3K

https://youtu.be/yqL3JS_igk4

Alan

Looking deeper into the Flex Meters;

Using the Flex API, I commanded Flex to show me the meter list.

For my Flex 6600, the PG-XL meter #12 is listed as an "External Meter," and is the "amp RL" value, meaning it gets the value from an external source, the PG-XL.

Flex Smart SDR uses meter #12 to calculate PG-XL SWR. The meter lists the meter output is scaled from 0 dB to 20 dB and is listed as PG-XL Return Loss (RL).

Return Loss is defined as "return loss is a measure in relative terms of the signal's power reflected by a discontinuity in a transmission line."

The formula to convert from Return Loss to SWR is:

where RL(dB) is the return loss in dB, Pi is the incident power and Pr is the reflected power.

where RL(dB) is the return loss in dB, Pi is the incident power and Pr is the reflected power.

Or for SWR:

For reference, 60dB RL is 1.0 SWR, 20dB RL is 1.22 SWR and 1 dB RL is 17 SWR.

Again, using the Flex API, I took a look at meter #12 output, with no TX. Meter #12 out was "20dB" (maximum scale value). Using the RL formula, this is an SWR of 1.22, which we see on our Smart SDR PG-XL panel.

Also, using the PG-XL API, I looked directly at what the PG-XL was reported as Return Loss, with no TX. The value was 60dB or an SWR of 1.0. However, my PG-XL utility shows an SWR of zero.

The PG-XL utility is causing the SWR indication to be zero, with no TX, but the Smart SDR indication for PG-XL is not using a TX flag (0) to show SWR as zero.

Interesting, with an RL scaled for a maximum of 20db, the Smart SDR will never show an SWR less than 1.22

In the case of the PG-XL, which outputs an RL of 60db, the best SWR indicated on its control panel will be 1.0.

Should be an easy fix for Flex to display zero SWR, when no TX, and rescale the RL range to 60dB, for a best SWR indication of 1.0.

Alan. WA9WUD

W8ASA

My concern is that because SSDR is showing 1.22:1 in the PGXL window, that it adds that amount to the measured value when transmitting, thus increasing my antenna's SWR from 1.9 to over 2.0, causing the amp to pull back on power. Ken W8ASA

Mike-VA3MW

@W8ASA

SWR is not cumulative, however, SWR varies along a feedline unless you are testing into a 50 ohm resistive load.

ARRL explains it in this article. https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf

If it was me, I would try by adding some feedline and see if that works around your situation.

Mark W Scott

I just upgraded to SSDR v2.8.1 and am seeing the exact same problem as Sergey (KN7K). The SWR is showing on PGXL SSDR screen without any TX. I am using PGXL v3.6.24, which I believe to be the latest version. Any thoughts?

K1UO Larry

This is a known bug and will be "fixed" in the next PGXL firmware release as stated above.