Digital Radio Setup

 

Dave,

Unfortunately – with some radios, the sensitivity of the SignaLink’s VOX isn’t high enough to make it actuate the PTT because your radio’s transmitter (modulation input) is so sensitive.  This results in a rotational setting of the front panel TX control that’s very low. There is a header / jumper to increase the sensitivity of the SignaLink’s VOX, and I wonder if you have that jumper set for the more sensitive position?

This doesn’t happen on any DRA operating under VARA (HF or FM) because of Hardware PTT.  It doesn’t happen on a DRA with VOX because I use a different channel to drive the VOX with its own level control. This puts the transmitter drive on the other channel with its own level control.

A simple way to set the modulation level for digital applications is to start out with the TX level control set to minimum.  Not all programs output the same transmit level, so this might need to be done every time you change to a different program.  Start by sending data or a test tone using the application you’re going to operate with.  While listening to a different radio set to the frequency your transmitting on, note the audio level.  If this is VARA or any other program that uses Hardware PTT, it’s possible (with a DRA) to key the transmitter and have no audio on the transmitter.  On a SignaLink, you’ll need to turn the TX level up until (at the very least) the transmitter keys.  Continue to send the test tone or data (multiple times if necessary) while slowly and carefully rotating the TX level control up noting the volume of this signal on your monitor radio.  Continue rotating until you perceive no more increase.  Then turn the control down slightly until you hear a reduction in volume.

This method is not perfect, but it attempts to keep the TX signal from becoming limited and distorted by the FM transmitters audio processing.

For DRA’s operating under Hardware PTT, it’s possible to set one TX channel up for the correct modulation of a particular program, and set up the opposite channel for a program outputting a different TX level.  Then – you can simply change the header / jumper driving the transmitter (JU5 on the DRA-50).  This allows R14 (R) to be set for one program and R16 (L) to be set for a different program.

Hope this helps…
Kevin W3KKC

On 11/8/2021 9:06 AM, Dave N3AC wrote:

Kevin,

I, and probably others, would like to see your alternative way to set the TX level… I’m about to light off the DRA-50 I just finished, and I also have a SignaLink that I barely get to tx on an old IC-V8000 (mike jack)… the AutoTune tells me to back down the TX on the Signalink, but I turn it down so far it stops transmitting before the AutoTune is happy…

thanks,
Dave N3AC

 


This one:
https://www.masterscommunications.com/products/radio-adapter/dra/pix/ICOM-7000.MOV

Brian,

While VARA and other programs have an auto-tune option, you need to roughly set the TX audio level (using the pots or Windows) to get in the ballpark. Here’s why….

Just like a VCR or cable box that includes its own ability to control the volume, you need to have the TVs volume set correctly to have a good range. You can’t turn the volume up any higher then what the TV is set to. If you have the volume on the TV cranked up, the appliances volume control is granular and hard to set. This is the same thing.

VARA cannot turn the TX level down if the DRA is set too high. On a radio that doesn’t need a lot of audio (like many ICOM radios) the level of the pots on the DRA (and/or Windows) needs to be reduced so the program has a chance to make it right. If the first level of auto-tune is already too hot, we can’t expect the program to be able to optimize it.

Conversely, VARA cannot turn the TX level up if the DRA is set too low. On a radio that needs a lot of audio (like many Yaesu radios) the level of the pots on the DRA (and/or Windows) needs to be increased so the program has a chance to make it right. If the last level of auto-tune is too low, we can’t expect the program to be able to optimize it.

In the video, you can hear when the radio is being overdriven – just before the TX LED starts flashing. At this point the audio sounds different because it’s distorted. It isn’t just changing level, it’s changing the waveform (which is not desired). In this instance, reducing the pot on the DRA will add usable steps in the TX level. This gives the program a better chance of optimizing the TX level because it’s less granular. Plus – once the audio becomes distorted, we don’t need to be cranking it up any more.

In summary – the pots on the DRA’s allow you “get it close” and then auto-tune can do a pretty good job of getting it right.

Kevin