Re: Ubitx v4 whining and swr check issue(?)

Bob Lunsford <nocrud222@...>

Hello. Here is my ham information and at the bottom, you can see
details of an End Fed Dipole that has worked for me. I have made
many of them but the way you place the coax is important. Check
it out:

Bob — KK5R


On Sun, 1/13/19, <budi.krisnawan@...> wrote:

Subject: [BITX20] Ubitx v4 whining and swr check issue(?)
Date: Sunday, January 13, 2019, 8:11 PM

Hi all, newbie here
Just got ubitx v4 last dec2018, installed and connected to
my endfed half wave thru 3:23 ratio balun (or un-un?).

Once i powered up i notice "whining" issue which
at 40m band it heard around 3-4khz (checked with spectroid)
which from another thread looks like this issue will be
fixed by replacing the nano board.

Once i calibrated it (to strong broadcast band) and set bfo
setting, i can hear local ham band properly, with addition
of the "whining".
Playing around the frequency dial, i notice that the whining
change (louder) when i dial down below 7.000.050. Means 7Mhz
and below had different whining sound compared to 7.000.050
and above

Well as my ordered nanos are on it's way, i set the cw
key to straight key, and use that to check my antena swr.
Antena was built with 20m long insulated wire(halfwave of
40m band), which theoretically should give me lower freq
than 7mhz. I checked with my swr meter (and ubitx cw) and
found that it dipped somewhere around 6.5mhz. Okay, i
shorten the wire and test again. Playing the frequency up
and down to find the new dip giving me surprise as when i
reach 7.000.050 and above it gave me very high swr.

I again check 7.000.000 and below. It gave me low enough swr
but when i dial 7000.050 and above the swr get very

This similar with my finding on the whining issue, that
7.000.050 number seem magical. This raise question :

Is ubitx limit the tx to be only on ham band?

If so, this may justify that below 7mhz i got low swr due to
"no" tx power applied, cmiiw.
I haven't check the firmware (v4.3) to see what happened
on 7.000.000 vs 7.000.050. If someone can give me hints,
that'd be welcomed.
Thanks for any help and sorry for my english.

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