Spuruious No Power Output

Lasse Moell

I have noticed an increase of occurance of transmitter dropping down to zero w output during a CW transmission. Just noticed this three times on 40 m right now. I am using a 6500 with 2.5.1 and Maestro, set to 25 w o/p driving an amp, all hooked up with cables. Searching the forum I notice this is not a new problem, it has been reported several times over the years. But somehow it has gotten worse lately (2.5.1?). By cycling to receive and start transmit again, magically the power returns. At a few instances I have noticed that the panafall shows zero output but the amp keeps on showing o/p, but is very rare, most of the time if output goes, the panafall shows no output either, but still in transmit mode. Also, very seldom, I can get power back by keep on sending CW, not reverting back to receive, usually I am in a QSO and want to keep on transmitting so rather than investigating the problem I just let the t/r relay drop. I understand this is a hard problem to nail as it is very random, and I have yet to see any pattern. I would like to hear from others to see if this is still a problem for other or if it is just my installation. At first I suspected my router as I sometimes see high latency (even if beeing on wired LAN) but today not so and still had this happen.

dlwarnberg

Ground loop possibly?  A ground loop will cause weird stuff to happen...  but I have not heard of anything like this

Lasse Moell

Forgot to mention, keying is made at radio, not through Maestro.
Here are a few that describes exactly the same issue (from what I can see):
https://community.flexradio.com/flexradio/topics/output-power
https://community.flexradio.com/flexradio/topics/intermittent-drop-of-power-output

But the last link may have a different issue as the power was reduced, not zero.

Transmit enable which comes from the amp is only read at the beginning of a transmit cycle, If it drops out for some odd reason this should then still allow output power, I just verified this. But it looks as if the radio decide to inhibit RF whilst still in transmit.

VE7ATJ_Don

To try to isolate the problem, maybe try keying just the Flex directly (at maybe 50 or 100W) without the connection to the amp.  Then see if you still see the dropout.  If it's OK, then I think we can at least eliminate a problem with the Flex itself, and focus on the interface with the amp.

Bill -VA3WTB

Is it doing it on a dummy load? if it is not then something down line from the radio is causing it.

Lasse Moell

I wish I could answer your questions... The problem is that it is spurious occations, can go days between I see it, or today it happened three times in just a few minutes. Could spend days trying to replicate the problem by sending into dummy load with and without amp. And if I do not see the issue I cannot be sure it is external.
Update: I managed to catch the fenomena while running bare foot... so it's not related to amp it seems.