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Soundcard calibration for TX ppm

 

I have calibrated my soundcard for receive using WWV to +127. What is the optimum method for determining the transmit ppm value? Other than sending an image to another station which has also been calibrated, then adjusting the value until the transmitted image is not skewed, I'm not finding a way. It seems there's probably an off-air method, but I'm not finding it. I don't think the help text covers setting the TX ppm value. I only discovered the need when I sent an image to an HF net and none of the stations received it correctly.
Thanks and 73,
Mark KE8NHT
Mike Black
 

What rig do you have -- sounds like you need to calibrate the rig.? The +127 is a lot to change on the receive side.
Look in the service manual for how to do it.

You can work with somebody who has also calibrated their receiver.

Contact me off-list and I can watch your signal.

Mike W9MDB




On Tuesday, December 10, 2024 at 12:19:13 PM CST, Mark KE8NHT Ohio via groups.io <ke8nht@...> wrote:


I have calibrated my soundcard for receive using WWV to +127. What is the optimum method for determining the transmit ppm value? Other than sending an image to another station which has also been calibrated, then adjusting the value until the transmitted image is not skewed, I'm not finding a way. It seems there's probably an off-air method, but I'm not finding it. I don't think the help text covers setting the TX ppm value. I only discovered the need when I sent an image to an HF net and none of the stations received it correctly.
Thanks and 73,
Mark KE8NHT
 

Hello Mark,

I hope the attached recipe will help...

73s Tobias
.-.-.

Am Dienstag, 10. Dezember 2024 um 19:19:13 MEZ hat Mark KE8NHT Ohio via groups.io <ke8nht@...> Folgendes geschrieben:







I have calibrated my soundcard for receive using WWV to +127. What is the optimum method for determining the transmit ppm value? Other than sending an image to another station which has also been calibrated, then adjusting the value until the transmitted image is not skewed, I'm not finding a way. It seems there's probably an off-air method, but I'm not finding it. I don't think the help text covers setting the TX ppm value. I only discovered the need when I sent an image to an HF net and none of the stations received it correctly.
Thanks and 73,
Mark KE8NHT

FLdigi_Soundcard_ppm_Calibration_Recipe_2024-12-10.zip
FLdigi_Soundcard_ppm_Calibration_Recipe_2024-12-10.zip

 

The rig is an IC-7300 using the internal soundcard. I didn't think +127 was much of a correction - I've had previous setups with much larger correction. If there's a procedure to calibrate the radio, I'm certainly open to giving that a shot. For now, receive works quite well.
I did calibrate the TX ppm with another user who, I believe, had already calibrated the receive system. I'd like to find a way to do this accurately off-air. I'm unaware of a way to get the transmit audio from the radio which would be the only way to accurately calibrate the transmit audio through the radio's internal soundcard. The TX ppm worked out to around +225, although probably not quite as accurately set as the RX ppm. Obviously, using the calibrated RX value helped but wasn't very close.
?
Mike Black
 


Mike W9MDB




On Wednesday, December 11, 2024 at 12:45:13 PM CST, Mark KE8NHT Ohio via groups.io <ke8nht@...> wrote:


The rig is an IC-7300 using the internal soundcard. I didn't think +127 was much of a correction - I've had previous setups with much larger correction. If there's a procedure to calibrate the radio, I'm certainly open to giving that a shot. For now, receive works quite well.
I did calibrate the TX ppm with another user who, I believe, had already calibrated the receive system. I'd like to find a way to do this accurately off-air. I'm unaware of a way to get the transmit audio from the radio which would be the only way to accurately calibrate the transmit audio through the radio's internal soundcard. The TX ppm worked out to around +225, although probably not quite as accurately set as the RX ppm. Obviously, using the calibrated RX value helped but wasn't very close.
?

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