Re: questions about µBitX v4 power + spectral purity mods


You made my day Dave!


At 06/08/2020, you wrote:
Have looked at but not for a couple of years. Didn't find it very helpful.

When I have put int the axiom relays I get about a half watt additional on most upper bands. Measured it on 4 different radios.
To my mind having that power released and not circulating around the filters has got to be a good thing as far as harmonics go.

I changed L5 and L7 as well.

Raj seemed to think that relays and the two inductors would give compliance so that is what I did. I respect him a lot.

Before you change anything, verify that the stock radio worked properly

One thing that you will definitely want is more gain on the receiver. I started with a computer speakers/amp. Then added an internal amp in the case. The V4 in particular is pathetic. I use a large loop (1300') antenna and found that they are very quiet so more gain is a good thing.

On the v3 40m has more power than 20m and each band above that is less.

The v4 that I have has more power on 20 than 40 and bands above 20 are stronger than they were on the v3, on 10 meters the v4 has close to 2x the power of the v3. Maybe 4 watts.

I don't worry at all about having less power on the upper bands. Seems like a lot of work for very little gain. (pun?) Not sure if any uBITX is perfect that way. Have made continental contacts on the approx 3 watts that my v3 has on 15m Worked all over europe on the 5w on 20. Made one contact ssb phone to Australia on 20m  over 8000 miles.

Have 90 DX countries with the uBITX The upper bands have been terrible so use 20-40-80 about 90% of the time.

Have made an air core 7 element 160 filter and hope to make more contacts on 160m this winter.
Raduino bracket and Ham_Made_Keys

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