Re: RD16HHF1 power curve flattening...some

John <passionfruit88@...>

Dear Mr Farhan, 

Thank you for your post. I also personally think that 10 watts is is a good number and I have set my rig at just under that on 15 to 10M.

Unfortunately to get to this  power level, the lower bands have to be above.

In my case that value is 16 to 17W on 80M. sloping to 9W on 15m and flat after that despite the mods that have been described in this thread (its original objective) and in other threads. The original variation as-built was, from memory, 10 to 1W variation across 40-10M, or 17 to 2W at higher PA voltage.

I am working on an 1st If shift based ALC/power limiter using the technique described in my other post and this will hopefully allow for a completely flat power curve over the bands.

But unfortunately this is expected to only work in SSB modes.

So the issue remains that the power curve as designed is quite steep.

My wish for a future version of the uBitx is, if there is one, and I sincerely hope there is, for a somewhat flatter curve. A maximum variation of 1 to 2 for example would be in my opinion quite acceptable.

While we are on the wishes, it would have made my modifications much simpler if the Si5351 was on the main board as it would allow to extend the I2C bus to whatever micro-controller we wished to use.

Finally, a big thank you for such a wonderful rig. It is such a pleasure to work with, and its customisation makes it an unparalleled match for our own needs.

All the best,

73, John (VK2ETA)

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