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D4D TX power

Fernando S
 

Hi!
I finally assembled my kit in a couple of hours, and I'm very happy with it.
Related to TX power, I read on the manual that needs to be set just at the minimum level that triggers the relay stably, so how much power is not being used before reaching an overdriving level? Is there any rule of thumb to raise the power a few db when minimum stably triggering level was found?

Thanks!

Adam Rong
 

Congratulations! 600mV is the threshold to trigger the VOX. However, about 50mV is the point to overdrive NE602 per KD1JV. That's why I recommend a modification to improve IMD. Rule of thumb for acceptable IMD: Decrease the audio input until you find the RF output becomes about half.

Thanks,
Adam

Fernando S
 

Thanks for the fast response Adam!
I did KD1JV diode mod (the left one on your photo below), and replacing C5 by the provided 105 capacitor.
Is there any other recommended mod? With the mods I made, the power needs to be calibrated just as manual says? (I doesn't have a power meter).

0.jpeg


El vie., 23 ago. 2019 a las 11:16, Adam Rong (<rongxh@...>) escribió:
Congratulations! 600mV is the threshold to trigger the VOX. However, about 50mV is the point to overdrive NE602 per KD1JV. That's why I recommend a modification to improve IMD. Rule of thumb for acceptable IMD: Decrease the audio input until you find the RF output becomes about half.

Thanks,
Adam

Adam Rong
 

The mods are good enough. Now you have the flexibility to pursue better IMD if you inject audio just above VOX trigger point, or higher RF output if you increase audio.

Thanks,
Adam

On Fri, Aug 23, 2019 at 10:27 PM Fernando S <fsclavo@...> wrote:
Thanks for the fast response Adam!
I did KD1JV diode mod (the left one on your photo below), and replacing C5 by the provided 105 capacitor.
Is there any other recommended mod? With the mods I made, the power needs to be calibrated just as manual says? (I doesn't have a power meter).

0.jpeg


El vie., 23 ago. 2019 a las 11:16, Adam Rong (<rongxh@...>) escribió:
Congratulations! 600mV is the threshold to trigger the VOX. However, about 50mV is the point to overdrive NE602 per KD1JV. That's why I recommend a modification to improve IMD. Rule of thumb for acceptable IMD: Decrease the audio input until you find the RF output becomes about half.

Thanks,
Adam



--
Thanks,
Adam Rong