Date   
Re: Narrow filter for CW #ubitxcw

Gordon Gibby
 

Too funny!


On Aug 16, 2019, at 09:10, Dale Hardin <joe.dale.hardin@...> wrote:

But, where will you mount the transceiver on the filter board?

Carrier suppression on uBITX v5 - -35 to -40 dB ok?

Rob French (KC4UPR)
 

For USB/LSB on the uBITX, what is a reasonable carrier suppression?  (and how is that properly measured, i.e. I assume it's carrier relative to peak?)

Background:  I should have left well enough alone, but... I've been using my uBITX for FT8 and PSK31, and had directly connected my uBITX mic input to my USB soundcard's headphone output, and my uBITX speaker output to my USB soundcard's mic input.  No special adapter circuits or anything.  Worked fine, bunch of good QSOs.  Fast forward, I was reading about interface circuits, and saw someone said that I MUST put a blocking capacitor between the respective inputs/outputs.  Well, I didn't do that.  Also read about someone saying that a few volts into the mic input could kill diodes in the balanced modulator, leading to carrier leak through.  So then I got paranoid and figured I should check my signal to make sure I hadn't done something like that.  Which brings us to now...

Test Setup:  uBITX v5 transmitting into a dummy load.  RTL-SDR dongle plugged into my PC, operating in direct mode.  "Tone generator": me whistling into the mic.  GQRX running on my PC to view the spectrum.  Just eyeballing the spectrum display.

Results:

(1) with background noise only ... noise floor ~ -75 to -80 dB on GQRX readout.  With PTT on, no tone, desired sideband ~ -75 to -70 db, carrier ~ -75 to -70 db (visibly distinct from desired sideband), opposite sideband absent.

(2) with a tone ... noise floor ~ -75 to -80 dB on GQRX readout.  With PTT on, "whistle" tone, desired sideband ~ -35 dB (peak), carrier seems to be unchanged (-70 to -75 or so), opposite sideband still absent (carrier kind of gets lost in the spectrum from my "whistle" at this point, but as I increase the volume from nothing, the carrier appears to be staying the same).

Does this all seem reasonable?  

Thanks!
-Rob

(PS - As an aside, I checked the DC bias on the USB sound card mic in and headphone out... mic in ~ 2V, which I assume it to drive electrets, and headphone out is 0V)

Re: Narrow filter for CW #ubitxcw

Dale Hardin
 

But, where will you mount the transceiver on the filter board?

Re: Narrow filter for CW #ubitxcw

Tom, wb6b
 

On Fri, Aug 16, 2019 at 04:13 AM, Gordon Gibby wrote:
Used toroids probably surplus from the phone company
Yes, those were popular back in the day for home-brew projects. Many folks built RTTY demodulators with them.

Tom, wb6b

Re: Narrow filter for CW #ubitxcw

Gordon Gibby
 

You can put in an op amp analog filter for very small outlay of cash.
I can remember building my first audio filter in the dark ages around 1973. Used toroids probably surplus from the phone company to build filters, and vacuum tubes to amplify the audio signals. Worked pretty good!!! Far far easier today.

Gordon

________________________________________
From: BITX20@groups.io <BITX20@groups.io> on behalf of _Dave_ K0MBT <davesters@...>
Sent: Friday, August 16, 2019 7:08 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw

Yes I was hoping to steal someones design and spend less than 10 dollars.

Have to agree that adding a 300 dollar filter to a radio that I bought used for 45 dollars is not going to happen.

Re: Narrow filter for CW #ubitxcw

_Dave_ K0MBT
 

Yes I was hoping to steal someones design and spend less than 10 dollars.

Have to agree that adding a 300 dollar filter to a radio that I bought used for 45 dollars is not going to happen.

Re: another stuck relay in TX mode #ubitx #bitx20

Peter LB0K
 

A stuck relay that releases on being tapped usually indicates that (some of) the contacts themselves are sticking together, presumably from arcing.

The only real cure with these small sealed units is to replace with a maybe beefier alternative, and in the longer term try and check whether the relay is in fact being commanded to open before the transmission has ended completely. Or maybe the transmission is starting some milliseconds before the relay contacts close properly.
For serious VHF/UHF work this what sequencers for the antenne and power switching arrangements are for, to make sure that the antenna changeovers are made before the signal starts, or after it ends. Thus ensuring the relays, and PA units, aren't subjected to unnecessary stresses.

For testing, one can make continuity checks across the contacts while is in the 'stuck' state to be certain of the diagnosis. But very often any slight movement or vibration will cause the relay contacts to release.

Of cause there could be a dry joint somewhere so reflowing all joints to the relay and its driver is an important first step. And see if the sticking still occurs at lower levels of, say, 10W.

73 Peter. 

Re: V5.1 and Nextion 5”

Murray Wills (ZL2IQ)
 

Image
Image
Hi everyone

Installed a separate PS and updated the display software. Very pleased with the results.

I also have a higher output regulator coming so the step down PS is only temporary. That board will be useful for other projects.

Thanks for all the help

73. Murray ZL2IQ




On Tue, Aug 6, 2019 at 11:11 AM +1200, "David Posthuma" <davep@...> wrote:

I used a 4.3-inch Nextion screen with no problems.

David Posthuma
WD8PUO

 

From: bitx20@groups.io on behalf of Murray Wills (ZL2IQ) <murray@...>
Sent: Monday, August 5, 2019 6:27 PM
To: bitx20@groups.io
Subject: Re: [BITX20] V5.1 and Nextion 5”
 

Thank you Evan for the time you have taken to help me out.

73 Murray ZL2IQ

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Evan Hand
Sent: Monday, 5 August 2019 11:11 PM
To: BITX20@groups.io
Subject: Re: [BITX20] V5.1 and Nextion 5”

 

Murray,

What Mike is saying is that the 5" screen may be too much for the 7805 5 volt regulator in the Raduino that comes with the uBitx.  There are a number of options, everything from modifying the Raduino regulator circuit, to simply adding another 7805 5 volt dc regulator. 

Background:
The 13.8 volt power supply is much more than the uBitx needs.  The 13.8 volts is good for the finals, however the rest of the board prefers the specified 12 volts.  That is why there are two power connections on the uBitx board.  The 7805 5 volt regulator on the Raduino runs off of the uBitx board supply, not the finals supply.  As currently connected it needs to drop that 13.8 volts to 5 volts.  The difference is dissipated as heat by the regulator.  The amount of heat  depends on the current draw through it. The recommended power supply for the display by Nextion is 5 volts at 1 amp.  Much more than the stock Raduino setup can provide.  

Here is the Nextion spec sheet:
https://nextion.itead.cc/datasheets/nx8048k050/ 

Suggestion:
Based on the current requirements I would suggest that you add another, separate 5 volt power for the Nextion display. This can be based on a 7806 type of regulator like one that is in the Raduino, however it will need a dropping resistor, heat sink, and the appropriate filter capacitors to work.  Another option is to by an assembled 12 volt to 5 volt reducer.  The watch out here is that it could generate noise as most are pulsed based circuits.

Here is an example datasheet for the 7805.
  https://www.sparkfun.com/datasheets/Components/LM7805.pdf

See figure 1 on page 7.  It gives typical input and output capacitor values, though does not cover a dropping resistor. 

Since the input is relatively high compared to the minimum required, and the power dissipation is dependent on the voltage drop times the current (nominal 13.8 - 5 = 8.8 volts times the max current of 1 amp = 8.8 watts).  Much higher than the design dissipation even with a heat sink.  Adding a voltage dropping resistor to get the dissipation lower is suggested.  The minimum specified input voltage is 7 volts.  I would use 8 volts to account for any variations in the input supply.  That means we need to drop the 13.8 volts to 8 volts with a resistor at the current draw of the specified 1 amp.  For this I would use a 4 or 5 ohm power resistor rated for 4 or 5 watts respectively.  Since this is the DC part of the radio, wire wound works well. The actual value of resistor would be 5.8 ohms and 6 watts.  You can go lower in value, just means more heat to be dissipated by the regulator, but do not go higher as at some point the input voltage may drop below minimum.

You will need to add a heat sink on the regulator.  This can be the case if it is aluminum, and you install the appropriate insulators for the mounting.  I would go with a separate heat sink similar to the one on the finals.

Another suggestion is to put a voltage drop between the 13.8 volt supply and the uBitx board.  This involves separating the red and brown power supply wires (per the supplied connector).   To that end I would recommend adding 2 4n4000 series diodes to drop the 13.8 volts to 12 volts to the RED wire.  4n4000 series diodes are rated for only 1 amp, so you will need to separate the finals supply and connect it directly to the 13.8 volt source.  If you do this modification as well, will need to go back and recalculate the voltage and resistor values for the Nextion display above.  I am using a 4 ohm 4 watt resistor in my setup, with the diodes to drop the voltage to the main uBitx board.

Please take the above with a grain of salt.  There may be errors, so verify.

Good luck with the build.

73
Evan
AC9TU

Re: Antuino support group opened -- early antuino question

Gerry Kavanagh
 

Different use case, IMO. I have a NanoVNA, and it's great for measuring passive devices' S11 & S21 parameters, but for signal measurement (spectral purity, power level) it is useless. This is why I ordered the Antuino.
/ Gerry

Re: Stuck relay

John Faivre
 

K1 is the Transmitt/Recieve relay. It was sticking in my v4
--
John Faivre WA9SGD

Re: another stuck relay in TX mode #ubitx #bitx20

John Faivre
 

I had the same issue. I replaced K1 with the axicom and it fixed it.i only run about 15 watts on 80 meters, but I was switching inductance on my ant tuner often while in transmit. I think that may have contributed to the proble, 
--
John Faivre WA9SGD

Re: Narrow filter for CW #ubitxcw

MadRadioModder
 

WOW! that Wolfwave filter cost upwards of $300 USD!!! My digital filter does everything it does and more (including a color display)... and was less than $50...

-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Richard Spohn
Sent: Thursday, August 15, 2019 1:56 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw

I believe this is where the Wolfwave comes in. It is a complete enclosure and GUI with the sotabeams DSP board at its core. A tad pricey but it does everything - including regenerating clean CW from a less-than-ideal signal. I fould it rather intriquing. - Rich WB2GXM

On 8/14/19, MadRadioModder <@MadRadioModder> wrote:
The sotabeams filters are exceedingly good technically. It's the
flexibility and user interface that's stinks. And, of course, it
can't be modified, even though the processor has plenty of resource
for additional computational things like a nice display to graphically
show you the filter contour.





From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of David
Posthuma
Sent: Wednesday, August 14, 2019 7:33 PM
To: bitx20@groups.io; bitx20@groups.io
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw



The sofa beams Audio DPS boards...there are several models...are stand
alone boards, no coach needed. Simply insert in your audio chain and
add power.
It
works great. Far better than I had hoped. They are worth the investment.



David Posthuma

WD8PUO



Get Outlook for iOS <https://aka.ms/o0ukef>



_____

From: bitx20@groups.io <mailto:bitx20@groups.io> on behalf of Tom,
wb6b <wb6b@... <mailto:wb6b@...> >
Sent: Wednesday, August 14, 2019 7:37 PM
To: bitx20@groups.io <mailto:bitx20@groups.io>
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw



On Tue, Aug 13, 2019 at 07:42 AM, MadRadioModder wrote:

I use my own coded version of this thing

That looks like a cool implementation. Is your audio bandpass filter
stand alone or is it an add-on to the Sotabeams filter board?

It sounds like it is a stand alone DSP filter and display.

Is the code on GitHub or somewhere?

Tom, wb6b





---
This email has been checked for viruses by AVG.
https://www.avg.com



--
…_. _._

Re: Narrow filter for CW #ubitxcw

Richard Spohn
 

I believe this is where the Wolfwave comes in. It is a complete
enclosure and GUI with the sotabeams DSP board at its core. A tad
pricey but it does everything - including regenerating clean CW from a
less-than-ideal signal. I fould it rather intriquing. - Rich WB2GXM

On 8/14/19, MadRadioModder <@MadRadioModder> wrote:
The sotabeams filters are exceedingly good technically. It's the
flexibility and user interface that's stinks. And, of course, it can't be
modified, even though the processor has plenty of resource for additional
computational things like a nice display to graphically show you the filter
contour.





From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of David
Posthuma
Sent: Wednesday, August 14, 2019 7:33 PM
To: bitx20@groups.io; bitx20@groups.io
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw



The sofa beams Audio DPS boards...there are several models...are stand
alone
boards, no coach needed. Simply insert in your audio chain and add power.
It
works great. Far better than I had hoped. They are worth the investment.



David Posthuma

WD8PUO



Get Outlook for iOS <https://aka.ms/o0ukef>



_____

From: bitx20@groups.io <mailto:bitx20@groups.io> on behalf of Tom, wb6b
<wb6b@... <mailto:wb6b@...> >
Sent: Wednesday, August 14, 2019 7:37 PM
To: bitx20@groups.io <mailto:bitx20@groups.io>
Subject: Re: [BITX20] Narrow filter for CW #ubitxcw



On Tue, Aug 13, 2019 at 07:42 AM, MadRadioModder wrote:

I use my own coded version of this thing

That looks like a cool implementation. Is your audio bandpass filter stand
alone or is it an add-on to the Sotabeams filter board?

It sounds like it is a stand alone DSP filter and display.

Is the code on GitHub or somewhere?

Tom, wb6b





---
This email has been checked for viruses by AVG.
https://www.avg.com



Re: another stuck relay in TX mode #ubitx #bitx20

Curt
 

Don

28 watts on 80m?  most of us are around 10 watts - could be an inaccurate power meter - or if you really are doing 20-some watts you could be over-driving badly. 

notice I am suspicious that relay itself may be still okay ....

you might have some RF getting into raduino that is locking it on transmit.  at the same time, its not wise to make this much RF with the ubitx - you could be jamming all kinds of fellow hams - for not much benefit on FT8.  if it does not lock up when doing SSB voice - another clue it may merely be too much drive into the PA. 

much better to solve it with an adjustment than to take the ubitx into unnecessary surgery! 

Curt

Re: another stuck relay in TX mode #ubitx #bitx20

Sam Tedesco
 

I have a bunch. I can mail you a couple.

Re: Calibration success #ubitx #calibration

kc0wox Leeper
 

I'm glad you found the answer. I looked at the schematic trying to make a suggestion on what to check but I have no experience with the ubitx. There has been quite a few Cobra mikes used over the last 10 years or so. http://golddredgervideo.com/kc0wox/cobramike.htm The main thing to watch is not to overdrive the bitx mike input.
Leonard

Re: Narrow filter for CW #ubitxcw

Dennis Zabawa
 

Go here for schematic and Arduino sketch: Filter

Re: Stuck relay

Gordon Gibby
 

Those relays are only rated for two amps @ a not very high voltage; Contacts will eventually wear out on any relay.  

You can probably find a slightly beefier relay, use it instead, and add a transistor buffer for the relay coil current if required


On Aug 15, 2019, at 05:30, KB2HSH <john.marranca@...> wrote:

I have a V3 uBITX that was stuck in TX last night...until I opened the rig up and tapped on the relays to "correct" the problem temporarily. Does anyone know which relay is to blame, and what the replacement is for it? Until this, it had been perfect for more than a year and a half. 



John KB2HSH 

Stuck relay

KB2HSH
 

I have a V3 uBITX that was stuck in TX last night...until I opened the rig up and tapped on the relays to "correct" the problem temporarily. Does anyone know which relay is to blame, and what the replacement is for it? Until this, it had been perfect for more than a year and a half. 



John KB2HSH 

Re: Antuino support group opened -- early antuino question

kh6sky
 

I don't think anyone has mentioned the nanoVNA.  These go from 50 kHz up to 900 MHz, color touch screen, built with rechargable battery and PC sw.  They cost less than 70 USD.  Look at https://groups.io/g/nanovna-users/

It is strong competition I am afraid for the antuino,  Though I will probably still get an antuino because it will no doubt be the learning and experimentation platform that the BitX radios have become.