Re: v5 Alive! (plus my advice, and thanks)

Laurence Oberman

Hello Curt

My V5 seems "mostly" improved over V4. I will try run some captures
for you this weekend.
My V4 since yanking the finals and pre-drivers is pretty clean at C84
and that is before I put it into the final filter section.
The weird heating spurs on 20m is gone, but I see a harmonic from 40m
at 28Mhz < 6DB down.
The final filter and relays may clean that up.
I am going to capture all of that and share it as its the signal that
will go into the circuit Allison shared prior to the QRP kits 10w


On Tue, Apr 2, 2019 at 3:31 PM Curt via Groups.Io
<> wrote:

Indeed nice progress on a nice rig ! Enjoy the ride.

I have seen very little spur data on v5, and I am seeing it to support curing my v4. Does anyone have especially SSB data on v5, although I am also interested in CW. I am skeptical that v5 is entirely air-worthy in most countries on all bands without some data.

Harmonics. Many v4 units have issues particularly on 40 and 30 meters, mine is harmonic compliant in stock form on other bands. I had heard one v5 having harmonic issues on 80 meters - it has a different arrangement of the relays. Two via solutions known to improve harmonics -- replace the relays with a superior part, or add a separate set of relays on a daughter board. Mine uses the later solution. This is the easier spur problem to fix.

Non-harmonic spurs. Generally showing up in SSB operation that uses the inverse of the receive path. Problems in v4 are generally above 20m, I imagine same for v5 - the degree is ?? Mine is dreadful on 12m - there I see the most spurs. A mixer product, a second pass through of the mixer, and leakage from clocks and the transmitted RF. As reported by N3SB, it can get interesting when efforts to cure SSB spurs impact the CW path (in our case only on 40m). I am especially interested in seeing more data - at least 2 hams claim to have completely cured their rigs in this regard -- the solution set some combination of a second narrow 45 MHz crystal filter, the better relays and replacing L5/L7 with shielded inductors. I think there is a bit more to learn here - Raj has cured his rig but I am wondering about the reproducibility of his cures across thousands of uBITX.

On 10m SSB I have only one non-compliant spur - its way below 28 MHz. But I imagine my triband yagi will radiate it well. 12m SSB is dreadful.

73 Curt

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