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Author Topic: Windows 7 VOX bug  (Read 3112 times)
N0ECK
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Posts: 3




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« on: December 22, 2012, 03:23:32 PM »

A few friends and I like to work MT-63 and other digital modes. It seems that our homebrew interfaces all have the same problem: When keying up using the radio's (or interface's) VOX circuit they will work fine with Windows XP but the adjustment is more than a little touchy with Windows 7.
In Windows 7 the radio will either lock in transmit until the audio level is dropped (after the software has stopped sending audio) or will not transmit at all until the level is increased. This happens with multiple interfaces, but we've only tried FLDIGI as the software.
Any ideas? I've googled all over and haven't found anyone with the solution.
Thanks,
KD0QEA
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AJ8MH
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« Reply #1 on: December 22, 2012, 06:04:55 PM »

I run my audio out of the computer at 100% for PSK and RTTY.  I set my home brew interface at mid position and set the transmit controls (audio and VOX) for proper operation.  I am running Dell-WIN 7 with fldigi and a Yaesu FT950.

I also use a home brew keying circuit with fldigi on CW only.  I did have trouble with the transistor staying keyed on 160 and 80, and had to place a .0047 cap across the transformer secondary in the interface.  On 10 the keying line would pulse (chatter), so I added a .01 across the keying line to the transmitter.

I have not noticed the issues you're having.
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VA7CPC
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Posts: 2414




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« Reply #2 on: December 22, 2012, 11:20:42 PM »

You talk about "VOX". 

. . . (a) Are you using VOX (a circuit which senses the amplitude of the AF drive, and closes the PTT circuit when AF drive is present) ?

. . . (b) Or are you letting the PC software generate a PTT signal on one of the pins of a (virtual) serial port?Are you using a USB-to-serial adapter between the PC and the rig (or the PC and whatever soundcard interface you have)?

If (b):

. . . Are you using a USB-to-serial adapter?

If so, on the Windows 7 PC, you should use one with the FTDI chipset, _not_ the Prolific chipset.  The Prolific chips work OK on Windows XP, but many people (including me) have had trouble with them under Windows 7.

Before tearing your hair out, try that change.

.         Charles
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NA4IT
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« Reply #3 on: December 23, 2012, 04:45:43 AM »

It is needful to note that MT-63, Olivia, Contestia, EasyPAL, and some other modes are a "low audio frequency" mode. It will require more drive to operate, as the "audio power" is not there. And some rigs may not be able to effectively operate these modes, as the transmit bandwidth may cut off higher than the frequency of the modes tones.
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AJ8MH
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« Reply #4 on: December 27, 2012, 11:05:12 AM »

I see from a post on QRZ.com that you're still trying to resolve your problem.  I decided to try MT63-500 just to see if the VOX reacted any different from the other digital modes I use. It didn't.  My configuration still works fine.

Again, I use a Dell desktop (Intel i3-2100 CPU @ 3.1GHz with 6GB RAM and WIN 7 with Service Pack 1) - Conexant HD Audio (default device) at 100% (full volume).  I use the rear panel jack.  Sound scheme is "No Sounds."  All enhancements are disabled (bass boost, room correction, etc).  I use 16 bit, 44100 Hz.  Exclusive Mode options are "allowed."  

I'm using FLdigi (3.21.64) with TX Level Attenuator (bottom row) set to -8 db.  (Note: Nothing is checked under audio config, right channel in FLdigi.)  Homebrew interface control is set to mid position.  (Homebrew interface is your common transformer type.)  I only use one channel of the stereo audio in each direction.  Unused channel floats.  Signal goes into (and comes from) the the FT-950 RTTY/PSK port.  Mode is set to USB/PKT and levels are set for TX/RX as needed.

VOX works on all modes I've tested including digital TV.

What rigs are you guys using?  Are you transmitting in the middle of the bandpass?  Anti-VOX set OK?  No RF feedback?

 
« Last Edit: December 27, 2012, 11:11:55 AM by AJ8MH » Logged
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