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Author Topic: Sticky Transmit  (Read 3581 times)
NF9K
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« on: October 20, 2012, 07:44:24 PM »

I've been wanting to do digital modes, starting with PSK31, since I got my HF privileges.  With a recent horse trade, I ended up with a RigBlaster II Plus.  Before the trade, I'd planned to purchased an Icom IC-7200 as a secondary HF rig due to it's direct USB connection or a SignaLink for use with my current setup.

I have a Yaesu FT-950 and my current shack computer is a Mac Mini.  I started playing around this afternoon and I had a successful QSO then all of a sudden, the PTT started sticking.  Doing some research, I found mention that some serial ports and DTR signals could cause the RigBlaster to stick on transmit.  Since the first occurrence this afternoon, I've not been able to get any software (FLDigi, CocoaModem, etc.) to key and unkey the FT-950.  I have noticed that if I unplug the RJ45 going to the FT-950, then the CocoaPTT software will key/unkey without issue.  The minute I plug in the FT-950, it sticks until I unplug the USB.

Initially I thought perhaps my issue was due to the software, so I tried various packages, all with the same result.  Since the OS X software is all open-source as well as the driver software, I decided to try a Windows XP laptop.  I've found the same issue with there as well.

I do have the Yaesu round/metal adapter installed inside the RigBlaster.  Not sure where else to look.  Since this RB was part of a trade, I have no proof that it isn't defective, other than the word of the previous owner.  Since I can unplug the cable going to the FT-950, and key/unkey over and over, I suspect that the RB is working fine.  Once the PTT starts sticking, the only way I can get the RB to unkey is to unplug and plug it back in.  So what am I missing?
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VA7CPC
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« Reply #1 on: October 21, 2012, 04:18:49 AM »

My bet:

. . . RF in the shack.

To test that hypothesis, run the rig at low power -- say, 5 watts (controlled by the RF POWER adjustment on the rig).

If everything is OK running 5 watts, and the PTT problem occurs only at higher power, you've found the culprit.

Fixes:

1) Put ferrite beads on _every wire_ going into the rig and _every wire_ going into the computer.

2)  If you don't have a balun, add one.   If you're using an unbalanced antenna (e.g., long wire), try something else.

.              Charles
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NF9K
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« Reply #2 on: October 21, 2012, 03:13:24 PM »

Unfortunately the problem persists at 5w.  So something is up with the USB communication to the RigBlaster.  I've been able to work around it by using vox.  While not my preferred method, I guess it'll work until I can try something else.
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VA7CPC
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« Reply #3 on: October 21, 2012, 11:16:50 PM »

A problem with USB  communication is possible -- but _the same problem_ under Windows XP and on a Mac?

I hadn't though to suggest a test at "no power".  If you turn down the audio TX signal to 0, you should get PTT action, but no power transmitted from the rig.

. . . If the problem persists, you know it is _not_ "RF in the shack".

If it goes away (and you may have to re-boot the computer, and re-start the rig, to make sure):

. . . . Put a ferrite core at each end of the USB cable.

.                 Charles

PS -- I don't always sing this note . . .
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K2CMH
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« Reply #4 on: October 27, 2012, 06:33:56 PM »

I had the same problem with a USB SignalLink.  It turned out to be RF causing the USB link to freeze/fail.  I have to admit however, I'm surprised that you would still see the problem at only 5w.  I ended up using chokes on the USB cable.
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WA9AFM
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« Reply #5 on: October 28, 2012, 06:33:48 AM »

This may sound simplistic, but try a different USB cable.  If you have a low quality or damaged cable, RF will work its' way into where it shouldn't be.
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NF9K
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« Reply #6 on: November 21, 2012, 08:55:33 PM »

I wanted to update this for the benefit of others who might STF for a similar issue....  I placed snap-on chokes from RatShack (yes, they actually stocked something useful, but I bought this particular store out) at each end of the USB cable and that seems to have resolved my issue. I've logged ~30 contacts since reverting to a non-VOX setup without issue.

Thanks to those that offered the suggestion!  I was surprised that the RIGblaster was negatively impacted by QRP power levels.
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AC4RD
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« Reply #7 on: November 23, 2012, 08:58:58 AM »

I was surprised that the RIGblaster was negatively impacted by QRP power levels.

Thanks for the update--that can be very helpful when others are looking for troubleshooting help. 

For the last couple of weeks, I've had a Rigblaster sitting on top of my 950's case, and haven't noticed a bit of problem with it.  But I *did* need ferrites on the cable between my keyer and the key input on the 950.   No telling why I had one problem and you had another--phases of the moon, maybe, or barometric pressure. :-)  But it's good to know you solved it, and how!
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