TX profile causing issues with PS

[VK3ICM]

G'day - I think this is a Thetis question, so posting here..

I see some weird behavior from time to time that I can't quite figure out. This is usually when I've done something dumb and caused a soft fault on my amp and it goes into Standby, but also on occasion when I get a hard fault and the amp shuts down. I'm actually not sure if this behavior is cause or effect of the amp faults in the first place. So basically:

1. The amp trips and goes into standby or shuts down, I power it back up (if required) and/or put it back in operate mode and status is normal
2. I hit tune in Thetis, radio TX relay clicks as normal, Thetis goes into TX
3. I can see from the Amp display and s/w the Amp is seeing RF from the radio at the usual level, but it is not producing any FWD power (Amp and LP-500 meter shows zero Fwd)
4. If I put the amp in Standby, and tune in Thetis I do see drive power on the meter - the amp is passing through drive RF as expected
5. Power cycling the AMP does not help

Sounds like an Amp problem, I agree, however only restarting Thetis gets things back to normal. Sometimes when this happens Thetis will not close cleanly and I have to kill it, but not always.

So when this happens, the radio is putting out drive, but seems to be also preventing the amp from TXing. I don't think this is a PTT line problem as the amp will give me a soft fault if it sees RF without PTT being closed and I'm not seeing this. I am using CAT in Thetis to communicate to the amp, but disabling/re-enabling CAT when the problem occurs seems to have no effect.

Any clues?

Cheers - Chris
VK3ICM / AG5RR

[w-u-2-o]

Which ANAN model hardware are you using?

[VK3ICM]

Which ANAN model hardware are you using?

Probably would have been marginally helpful for me to include some detail:

Anan 7000DLE mk2, P2, Thetis v2.7.0,

[va7qi]

Same hardware here; same fault. The radio gives very low output on tune. In my case I don't think it was a fault in the amplifier, but it happens occasionally and the cure is to turn power off Thetis as well as the 7000. Could be that RF gets into the computer. I often run QRO.

73 de va7qi, ....Erik.

[laurencebarker]

I have observed what sounds like a similar issue while developing an auto ATU. In that work, the PA sees a high VSWR during the tune cycle. If at the end of TUNE there was a high VSWR, then next time I pressed TUNE I got low forward power. Go back to RX and press TUNE again and it was fine.

I haven't had a chance to investigate this yet; I'm wondering if there is some record of a high VSWR that has been retained in memory.

If you press TUNE again does that make a difference, or does it really need a restart?

[VK3ICM]

If you press TUNE again does that make a difference, or does it really need a restart?

Hi Laurence - in my case it seems to absolutely need a Thetis restart. I'm not certain I'm seeing low Tune power in my instance. if I put the amp in standby, I do see the expected tune power bypassed through the amp. The next time it occurs I'll put the meter on the output of the 7000 to verify.

[laurencebarker]

I'm wondering if the CAT handler has locked up. Could you close the CAT channel and re-open it in a different channel (CAT2-4 on the CAT+ tab)? I wouldn't know how to fix that, but it would give us a clue about what's happening.

[Joe-W4WT]

I believe this is an issue with the Drive control. I see it frequently. I will adjust the drive control to, say, 22 and press tune and get close to zero watts out. Bump the drive to 23 and then the output is just fine. Been doing this a long time for me.

Next time you see this happen, just bump the drive up one or down one and see if that solves the problem.

Joe W4WT

[va7qi]

Hi Laurence,

It looks like the database got corrupted. I had to re-load an old version. One of the other problems showing up is that it increases the S-meter readings by several S-units.

You may well be right that it relates to tuning. I mainly run WSJT-X and change bands many times during the day. Each time the amplifier needs to tune, so the SWR warning flashes briefly on Thetis. However, I also get some RF into the computer when operating 6m (and six was hot tonight...) which could explain some of the problems.

73 de va7qi, ....Erik.

[VK3ICM]

Next time you see this happen, just bump the drive up one or down one and see if that solves the problem.

It happened a couple of times over the weekend. Changing drive didnt seem to help, nor changing the CAT ports, however turning PS-A off and on again restored normal operating.

Really not sure at this point.

[VK3ICM]

(G'day Scott - feel free to move this to the PS or Amp forum if more relevant)

Did a little more digging, and PureSignal seems to have something to do with my amp tripping issue.

When the trips occur, momentarily the TX spectrum looks horrible and overloaded, the PS indicator is blue, and Amp View shows a mess as though the amp is being over driven.

A couple of things I don't understand - this occurs with my usual drive level that 99% of the time behaves perfectly, with some margin below the rated power of the amp. More confusing to me is that this only happens with PS on. With it off, I'm unable to replicate the problem - same drive level (or higher), same antenna.

It is as though PS goes nuts for an instant, causing IMD on the amp output and (and overloading the PS input maybe?), creating a high SWR condition which is causing the trip. I do not see power or SWR spikes on my inline meter though - maybe its too fast and the amp protection cuts in quickly.

Anyone have any thoughts why PS on/off is making a difference here?

[w-u-2-o]

I re-read the topic but not did not see what model amp you are using?

[VK3ICM]

It's an Acom 700S.

PS feedback is via a modified Telepost coupler with a -55db sample port. I do have a -44db Xtronic one here I could swap out. I could also try Thetis 2.6.9 or a different fw (running Metis_Orion_MkII_Protocol_2_v2.0b).

Cheers

[w-u-2-o]

Hmmmm, an Acom amp. Acom amps have been known to demonstrate some unique behaviors. For instance take a look at this topic:

viewtopic.php?f=15&t=2593&p=3946

I'm going to guess that the behavior you are seeing may be related to the Acom 700S specifically. With your concurrence I'm going to move this topic to the amp sub-forum and add "Acom 700S" to the title. OK?

Thanks,

Scott

[VK3ICM]

Yep - I've seen that and worked around it by changing the frequencies in the Two Tone test in Thetis. Is your hypothesis that potentially whatever is in the Acom firmware to disable 'standard' two tone tests may be a trigger to this behavior?

I also noticed my mic level in Thetis is exceeding 0db by some way on peaks (must have bumped the level on the Motu audio interface). I guess this could potentially trigger overload, but doesn't explain why PS on or off makes a difference.

Ok to move to the amp forum.

[w-u-2-o]

I'm guessing, obviously, but very suspicious of the amp. It's very interesting to read your report that Acom duplicated the two-tone issue in the 700S as well.

Having hot audio is no big deal (other than how it sounds) because the ALC built into both PowerSDR and Thetis will not allow the drive level to exceed the maximum value you have selected. With no hardware ALC, the proper method to check drive level is to use either single or two-tone to check your max. drive prior to operating. If you are happy with it after that check you can rest assured the software ALC will not allow it to exceed that.

[VK3ICM]

Thanks Scott. I have had good support from Acom so far. I've just queried them re. the two tone behavior and if they have input on potential impact to adaptive pre-distortion. I'll share what I hear.

[VK3ICM]

I managed to capture an example of my TX spectrum and AmpView exhibiting the symptoms that lead to my Amp faults. I'm using a dummy load here and things look normal with PS in the first count, but counts 2 and 3 seem to show something wrong. Only occurs with PS on.



My sense is this occurs more often when my PC is under greater load. When I ran OBS (thanks for that tip in another thread Scott) to do the screen record, CPU was close to 100% and I was able to catch the behavior easily. Usually it is fairly infrequent, but enough to be annoying.

Is PS highly dependent on system resources, or is it more dependent on the the FPGA in the radio? I'm running a Core i5-6600k, 16GB ram, integrated graphics - typically my system is around 50-70% when operating. I downgraded Thetis to see if it made a difference - nope.. Next I might see if i can replicate the issue using LinHPSDR.

I don't think this is Amp related as I've seen the same behavior in the TX spectrum (only with PS on) with the amp in standby.

As an aside - Acom was surprised to hear the problem with the two tone tests was still present. They indicated that in early firmware the frequency counter software was not reading the tones correctly (and the amp will not go into TX with an unknown freq) - they will look into it.

[VK3ICM]

I also see PS 'fails to launch' sometimes. In this series of two tone tests, PS works intermittently. I see this when operating phone - on some overs it doesn't give any indication at all, and from the spectrum it is clear it's not doing its magic.

[VK3ICM]

Well - early days but looks like success..

Tried another amp and was able to reproduce the same behavior. I noticed that with my TX EQ enabled it was much easier to cause the problem. Set a new profile from scratch and it has been 100%. Even with PS-off the TX spectrum looks MUCH better.

Possible a corrupt TX profile could lead to distorted output?

[w-u-2-o]

Since this wasn't an amp problem, per the OP's (original poster's) request, moving this back to the Thetis sub-forum.