Date   
Re: Harmonics and Relay Replacement

Nick VK4PP
 

Hi All.

Just wondering, With the new LPF board I'm working on, how do people feel about having the ND6T agc integrated on the board as well?

I think there is enough space to fit it in there and still maintain the same footprint of the existing LPF section.

Thoughts?
73 Nick VK4PP

Ubitx v4 whining and swr check issue(?)

BK
 

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 high. 

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.

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

_Dave_ K0MBT
 

I got a used ubitxv4 that had that sort of a whine. Turns out the BFO was off about 2k. Go through the setup and start with the standard bfo freq of 11.9965mc, then adjust from there.

Maybe you have the same problem.

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:

https://hamcall.net/call?callsign=kk5r

Bob — KK5R

--------------------------------------------

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

Subject: [BITX20] Ubitx v4 whining and swr check issue(?)
To: BITX20@groups.io
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
high. 

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.

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

Evan Hand
 

The stock software for the uBitx does cut the VFO so that there is not any RF out.  There is a check on the VFO setting below 7.000,000.1 to shut it down on transmit.  I have not checked on where the band change to the next lower band, however it does turn back on at some point.  I am not at a terminal where I can review the code to let you know the exact frequency.

73
Evan
AC9TU

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

BK
 

This whining is always there even if i disconnect the antenna so i believe this is not corelate to bfo (and yes i have set the bfo properly).

When i touch around the ubitx board, nothing i touch changes the sound, but when i touch 25mhz crystal pin it does change the sound of the whining. Other than that is by moving the frequency to 7mhz and below. Anyhow thanks for the reply. Today i installed cec firmware v1.08, and do the same test around 7mhz. The same symptoms still there:
-7mhz and below makes my swr low and thw whining sound increase in volume (and or in freq)
-7.000.050 and above make my swr very high. 
I think i need an oscilloscope to see more of what happened. 

Re: Tracing receive signal for low signal

Dave Space
 


I am going to declare the audio pre-amp a success.  To compare I generated a signal off my signal generator into the air  (no direct connection) and listened for the lowest level I could hear it on my Yaesu which was 20mv out on my generator as barely audible and 40mv audible.  I then connected the ubitx to the same antenna and tested and it is now on par with the Yaesu in terms of at least level of hearing a faint signal and pretty close on a strong signal. (it might even be slightly better on the uBitx now)

Thanks everyone especially Evan and Jim for all of the ideas to get to there.  I do kind of wish we figured out why the board is anemic but I'm good with taking a win :)

I'm trying to decide if I want to tackle the transmit issue (I think I heard it transmit off frequency slightly like 3khz low or something) next or try to add an AGC. (I'm thinking worst case if I can ever get software to load on the Radiuno I can rewrite the software to transmit at a slightly off frequency to compensate for the transmit problem - My day job is in the software development area :) )

Re: uBix - transmit clicking when Mic inserted

Gary Anderson
 

From the HF signals schematic and wire-up diagram (original V3 sourced in ~Feb/March 2018), it doesn't look like the designer anticipated that the Mic/PTT plug would be plugged-in after uBITX power-up.
I think this is where Raj is going when he suggests swapping PTT and Mic wires (on both the uBITX and your mic)

The original supplied V3 wire-up has:
Tip = "Mic" = 4.7K ohm resistor to TX (12V when in TX mode)
Ring = PTT = internal Nano pull-up to 5V
Sleeve = GND

When you plug in a TRS plug to the jack supplied in the kit, the Sleeve to Ring (jack side) can easily short if it is off on angle.
The internal springs in the jack help get the plug off angle  (at least on mine)
A short between PTT and GND puts the uBITX in TX mode.

As you continue to push in the plug, you short Tip to Ring on the jack. (You can see this through the clear plastic window on the jack)
For a brief moment if your uBITX went into TX mode, a second operating condition fault scenario:  4.7K Ohm pull-up to 12V on the Nano. 
Now you are depending on the ESD protection diodes internally to the Nano to protect from Electrical Over Stress.

Swapping Mic and PTT positions would seem to be more robust (I have not fully vetted this solution.)
You would still have the above Tip to Ring fault mode if you accidentally unplugged the while the uBITX was in TX mode.
(so not 100% robust, but that is much less likely to happen often enough to be of much concern, and if the Nano goes 'bad'; you have a clue)

Regards,
Gary




Re: Tracing receive signal for low signal

Evan Hand
 

You are welcome, though it the transmitter is off by 3khz, that is an indication that the calibration is off, and the 3khz off would put it outside of the 2.5khz bandpass for the 12mhz filter.  I would start with calibrating the VFO (clock#2) to be on freq. with CW key.  Then go back and verify the BFO.

Off calibarion is a know issue with the uBitx v4. When not calibrated, the sensitivity is very low.  Get it calibrated, and the receiver is as sensitive as most 10x the cost commercial rigs (that is the case with my v4 uBitix compared to my Icom IC-7300).  The Icom has more features to help with selectivity (and a host of others), however it is not much better at pure sensitivity of the signal over the noise floor.

73
Evan
AC9TU

Re: Tracing receive signal for low signal

Dave Space
 

Thanks again.  Question wouldn't calibration impact both receive and transmit?  In this case receive seems spot (same frequency matches on Yaesu and ubitx and can zero beat on tone) on but I think transmit was off.  BFO frequency seemed good on receive.  I'll need to retest to be sure. 

uBitx worked, shut off, now no audio

Nick
 

Hello, all!

I finished the assembly of my uBitx and case. I turned it on and it seemed to be working. I did not have an antenna attached so was only hearing noise, but It would only stay on for about ten seconds before it would shut off. This happened several times; I thought it might have been because I had no microphone or key attached. Once, as I was adjusting the tuner, the unit shut itself off but this time when I cycled the power and turned it back on, the audio was completely gone. I have checked for loose connections but can't find anything wrong. It appears to power up fine, the tuner and menu functions are working, the only problem is zero audio on both the speaker and the headphone. Interestingly, now that I have no audio the radio is not shutting of anymore.

I'm hoping someone will have some insight as to why the unit shut off repeatedly and now stays on but is is deaf. Any help will be appreciated!!!

Nick
W3VN

Re: #bitx40 BITX40 Winlink configuration #bitx40

rick
 

I'm attempting the same thing.  Would be grateful if you'd elaborate on the signal conditioning circuit.
Thanks!

rick

Re: si5351 crosstalk #radiuno

Glenn
 

This is a fairly old thread but I recently did some testing on my own version Si5351 board with buffer chips on each output, which maybe of interest.   I only tested 2 outputs, 0 and 2, for cross-talk as I had a VFO/BFO Raduino style board set-up to test. Frequencies of ~10.7MHz and 17.8MHz so can only comment on this setup. There maybe differences at other frequencies etc.

My Si5351 PCB is based on the Adafruit style and Sch with same pin-out, and the comparison was between the Adafruit and my buffered version. The buffered outputs were fed thru a 47R resistor and 100nF cap to the SA in the buffered board.  And only via a 100nF cap in the Adafruit version. ie Raduino style. Each of the 74LVC1G04GW buffer chips was supplied with Vcc via it's own ferrite bead and 100nF cap to ground, filter. (not visible, as on bottom of the PCB)

Typical cross-talk of the Adafruit board was around -50dB from output 0 to 2 or output 2 to 0. Output levels into the SA at fundamental, approx. +4dBm.

My buffered version was better by around 8-10dB for cross-talk and output at fundamental increased to approx. +8-9dBm.

Glenn vk3pe




On Sat, Sep 22, 2018 at 07:43 PM, <lynatmts@...> wrote:
Hey Glenn, So what were the results of adding the buffer stages? 
Thanks

Lyn
--
"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat."

Re: Mini PA für my uBITX #ubitx

DC3MS
 

Bob, i deeply respect long time hams sharing their vast knowledge with new-to-ham Operators,
but i really didnt expect this discussion to start.
Sure its not necessary, nor is it necessary that i recap an Heathkit SB101, SB610, SB620 and build
an extra Hamdesk in the basement to set the line up together with the just acquired SB200.
If i would do my antenna and CW work right, all i needed would be pixie monobanders for each band.
I am not complaining about objections regarding signal quality - i think that is pretty important.

Re: Mini PA für my uBITX #ubitx

Bob Lunsford <nocrud222@...>
 

Mark, I'm in the process of getting a BITX40 (waiting for
shipping notification and tracking number) and those
old Heathkit days are moving into hazy history and a
desire to never revisit them. The only thing I have now
is an HW-2036 2M for monitoring 52S mostly and a
RS HTX-252. I live in a 2M depressed area.

I've build nearly everything Heath had. Had an HW-104
and an SB-104 but the FT-450AT I had made them look
like WW1 submarines. I even had a Drake TR7 which
was to me the Cadillac of HF radios but the 450 was
much better for me. All that is gone now. Moving into
the HF Signals arena.

These Ubitx/TITX40 radios are great. It's a new kind
of technology to me with the Raduino. The UbitX is
surprisingly good on reception and this means from
500KHz to 30MHz.

Big question is, when will the V5 board be available?

Bob — KK5R

--------------------------------------------

On Mon, 1/14/19, DC3MS <mark.schraven@...> wrote:

Subject: Re: [BITX20] Mini PA für my uBITX #ubitx
To: BITX20@groups.io
Date: Monday, January 14, 2019, 1:23 AM

Bob,
i deeply respect long time hams sharing their vast knowledge
with new-to-ham Operators,
but i really
didnt expect this discussion to start.
Sure
its not necessary,
nor is it necessary
that i recap an Heathkit SB101, SB610, SB620 and build
an extra Hamdesk in the basement to set the
line up together with the just acquired SB200.
If i would do my antenna and CW work right, all
i needed would be pixie monobanders for each band.
I am not complaining about objections regarding
signal quality - i think that is pretty
important.

Re: ND6T AGC Troubleshooting

DJ2AG
 

Hi Rich,

thanks for the diagram. Will give it at try.

Armin, DJ2AG

Re: Mini PA für my uBITX #ubitx

DC3MS
 

See - thats what i really like ham radio for. There is no technical or practical reason to spend month on getting the 50 years old HK equipment back in shape - except me finding it fascinating.

I could buy some up to date transceiver for the Money (or even half of it) , but thats just not my kind of fun. I always wanted a Heathkit. Even if its only because of its looks :) 

I also like the uBitx because of the Arduino, which is something i use on a regular basis. 

Just wanted to use a Nano to control a linear and try the i2c connection and a nextion.

No show-off. No really need. But i for sure see a difference in range on 40/80m running FT8 on my homemade HF2V vertical. And it was fun to put together.

Re: Tracing receive signal for low signal

Evan Hand
 

As I understand it, the VFO is not changed UNLESS you have the RIT set.  I should have asked you to verify that first.

73
Evan
AC9TU

Re: uBitx worked, shut off, now no audio

Vic WA4THR
 

Which version of the uBitX? If it is a v.3 board most likely the audio amplifier chip (begins with WX) has failed, a common issue. If it is a late version of that board the chip will be in a socket and easily replaced with a better one.

=Vic=

QCX

Dave Dixon
 

LOKKING FOR A QCX TRANSCEIVER.
band not important.
must be in the uk...