No Sidetone on V16, frequency tuning

[FlyingCanuck]

I've got my V16 with Razor (also a N16, head in NAVCOM mode) working now. The Razor head is connected via RS232 to a Dynon Skyview HDX display and is emulating an SL30.

I have 2 outstanding issues - neither is critical, but I'd like to see if there is a fix.

1) I cannot get sidetone to work, I've tried both settings, I get good TX and RX, I just can't hear what I'm transmitting. This only causes a bit of a confidence problem, I'm not sure I'm actually transmitting unless I get a response.

2) I can't seem to tune a 25 MHz frequency from my HDX, one of the local frequencies here is 122.875. If I tune that on the HDX, it shortens it to 122.800. I can't tune it from the Razor either unless I have the RS232 disconnected from the HDX (I use a toggle switch to select the COM radio that the HDX connects to via RS232).

Any ideas on these issues?

Thanks
Claude

[adamoconnor]

1) I cannot get sidetone to work, I've tried both settings, I get good TX and RX, I just can't hear what I'm transmitting. This only causes a bit of a confidence problem, I'm not sure I'm actually transmitting unless I get a response.

There's two things that cause sidetone to work - 1 is IC volume, 2 is related to the source of sidetone. In my experience, the sidetone source being modulator has yielded better results, however you may find antenna to be better. Whichever one you are set to, try the other.

2) I can't seem to tune a 25 MHz frequency from my HDX, one of the local frequencies here is 122.875. If I tune that on the HDX, it shortens it to 122.800. I can't tune it from the Razor either unless I have the RS232 disconnected from the HDX (I use a toggle switch to select the COM radio that the HDX connects to via RS232).

How old is your Razor? There was a firmware update posted some time ago that addresses an issue with the SL30 interface. Scroll down to the bottom here: http://mglavionics.co.za/rfdf.html

Adam

[FlyingCanuck]

Thanks Adam. If side tone requires IC volume then that is likely my issue. I don't use the intercom feature as I have an audio panel, so the volume is all the way down. I'll try and see if increasing the volume helps. I've tried both modulator and antenna, I'll check to see which works better if the IC volume works to get me side tone.

I bought my Razor from you about 5 months ago. Thanks for the link, it describes my issue exactly so I'm sure that's the fix. I've got what I need to build a serial cable to apply this update. I'll give it a try.

Thanks for the help.

Claude

[rainier]

To clarify,
yes the sidetone is coupled to the intercom volume (it is actually used as a reference to tweak your MIC gain on the V16 as the sidetone is subject to automatic gain control and the level is adjusted automatically over a wide range - so that is why you use TX with the sidetone as reference to compare the loudness of the normal intercom function and adjust the microphone gain until both have the same loudness.

The sidetone can be picked up from two sources in the V16 - the first is from a small demodulation circuit right at the antenna output - so you actually hear the modulated carrier as it leaves the radio.
The second option takes the sound from the modulator itself - this is removed from the antenna connector by a series of filters.

The antenna source can sometimes give a bad result - it depends on your antenna cable length, tuned frequency and the antenna match itself - a bad result (sound too soft or too loud or distorted) indicates a less than ideal antenna connection, effectively an acoustic feedback related to SWR. This effect is due to the overlap between outgoing and reflected waves.
Switching to modulator isolates the reflected wave from the sidetone to a very large degree as the reflected wave is transformed down in level greatly due to the impedance conversion nature of the transmitters harmonics filter.

[FlyingCanuck]

Thanks Rainier, I tried transmitting with a bit of IC volume and I do get side tone but I have a rising audio feedback as I hold the PTT. It only takes a few seconds to be problematic, but this is without speaking, it might be better if I'm talking. This happens regardless of the Antenna/Modulation setting.

With the Razor firmware upgrade, it is proving to be difficult. I have a USB to DB9 Serial adapter and I built a DB15 connector to provide RX/TX/GND from the DB9 as well as power. This doesn't appear to work regardless of which COM port I select on the firmware update program. Is there a way to test the COM port connection before trying the updater program?

[rainier]

Thanks Rainier, I tried transmitting with a bit of IC volume and I do get side tone but I have a rising audio feedback as I hold the PTT. It only takes a few seconds to be problematic, but this is without speaking, it might be better if I'm talking. This happens regardless of the Antenna/Modulation setting.

There are two possible feedback paths - via the audio wiring/connections or from the transmitted signal itself back into your audio system via one of several possible paths.
As you report clear transmission we can exclude the RF feedback.

That leaves audio - somehow the signal from the V16 audio output is getting back into the MIC input -that of course sets up the feedback path and howling is the typical result. A favorite path for this (in my experience) is a longish audio cable where MIC and audio out leads are running next to each other and are not separated by shielding or the shielding is very poor.
On some intercom systems you also need to be careful that you configure it in a way so any audio received by a connected radio is not sent back that way - keep in mind that can even happen in your headset/headset wiring as both signal lines are also present there.

With the Razor firmware upgrade, it is proving to be difficult. I have a USB to DB9 Serial adapter and I built a DB15 connector to provide RX/TX/GND from the DB9 as well as power. This doesn't appear to work regardless of which COM port I select on the firmware update program. Is there a way to test the COM port connection before trying the updater program?

I am assuming you are referring to a DB25 connector ? If it is a DB15 you are dealing with a V6 radio - not the V16.
On Windows, open a terminal emulator or download one (many free ones available - I like TeraTerm) - select your port at 9600 baud.
When you switch on the radio you should see the characters "OK". If you see that the PC can see the V16.
If you bridge TX and RX (without radio connected) whatever you type on your keyboard should appear on the screen.

The update program waits for the OK - if it gets that it sends the characters ESC+"PROG" (ESC = 0x27). No + or quotes. If the radio sees that immediately after sending the OK it will answer with a "#". If that happens all is well (you need to type the ESC and PROG quite fast - the V16 is not going to wait a long time for this)