Date   

Checking SWR with BITx40

Scott Skroch <sskroch@...>
 

My son purchased a BITx40 and we thought it would be a good idea to check the SWR of his home made antenna before transmitting too much.
 
The problem we have run into is that his BITx40 only puts out a fraction of a Watt of power (.016 W) unless we are speaking into the microphone.  We are not able to use our SWR bridge with the low power.
 
1. Is this normal for a BITX40?
 
2. Is there a standard way to increase the power to the antenna for these types of measurements?  (We could just set up a speaker next to the microphone to give consistent white noise input to the mic but this does not seem right.) 
 
 
Voltage measurements were taken with a multimeter on the output leads of a 50 Ohm dummy load.
1.05V without speaking into the microphone (1.05V)^2 / 50 Ohm *.707 = .016 W (RMS power)
18V Loudly speaking into the microphone (18V)^2 / 50 Ohm *.707 = 4.58 W (RMS power)
 
Thanks,
Scott


Re: uBITX v3 programming #arduino #ubitx

Chris Cancilla
 

Have to look at that on Saturday, this will be a busy week.

As for the standby, yes, it is receive actually.

On Sun, May 17, 2020, 9:22 PM Evan Hand <elhandjr@...> wrote:
Chris,

The only time that any of the 3 uBITX ( 6 PA transistors) that I have get warm is when running digital mode for an extended period of time.  I would check the bias setting of the finals.  The finals setup should be the same as the version 4 wireup instructions here: https://www.hfsignals.com/index.php/ubitx-wire-up/ and Tune-Up: https://www.hfsignals.com/index.php/ubitx-tuneup/

Note: ALL of my Raduino voltage regulators get HOT.  That is normal.  The regulator is on the board that is at right angles to the mainboard on the left side looking at the display.

After writing the above, I realize that you should explain what you mean by standby.  There is only transmit and receive as far as I know.

73
Evan
AC9TU


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: Test equipment recommendations

Curt
 

I suggest slowly figuring what you really need, watching for inexpensive club and merchant kits. A xtal oscillator makes a great signal generator or consider a pll signal generator from qrp labs or usr signals on the air. A qrp power meter is useful, but a diode detector and dvm can work also. Don't work too hard to find a used 100 mhz scope, one can be had cheaply if you are patient. Enjoy the journey.

Curt wb8yyy


Re: uBITX v3 programming #arduino #ubitx

Evan Hand
 

Chris,

The only time that any of the 3 uBITX ( 6 PA transistors) that I have get warm is when running digital mode for an extended period of time.  I would check the bias setting of the finals.  The finals setup should be the same as the version 4 wireup instructions here: https://www.hfsignals.com/index.php/ubitx-wire-up/ and Tune-Up: https://www.hfsignals.com/index.php/ubitx-tuneup/

Note: ALL of my Raduino voltage regulators get HOT.  That is normal.  The regulator is on the board that is at right angles to the mainboard on the left side looking at the display.

After writing the above, I realize that you should explain what you mean by standby.  There is only transmit and receive as far as I know.

73
Evan
AC9TU


Re: uBITX v3 programming #arduino #ubitx

Evan Hand
 

Glad that it worked for you.

73
Evan
AC9TU


Re: Test equipment recommendations

Robert D. Bowers
 

No.  I got it off of eBay.  I'd have to look it up (it's out in my shop).  It came from China as I remember.

I've got a couple of those $10-$15 Radio Shack multimeters - one out back, and one in the tool box in my van.  They'll do 90% of what you usually need one for (especially with probes like for RF snooping).  In my shop/home lab, I needed one with additional functions - like peak hold and digital output - which gets occasional use.  For more really complicated stuff I turn to my good digitizer scope.  IMO, a good meter is something that as you get more experienced, the more you'll appreciate the 'extras' - especially if you don't have access to the really good equipment.  Mine isn't the best unit available, but it's accurate and precise enough for what I do - and it has adequate safety stuff built in. 

I probably grab the meter about 80% of the time... my scopes come next (probably 10%), followed by the other equipment.

On 5/17/20 8:10 PM, Reed N wrote:
Hi Bob,

For home/hobby use, I have a Best DT-9205M. It's not a high quality multimeter, but it measures AC and DC voltage and current, resistance, and capacitance. It's good enough for order of magnitude capacitance (is this a 0.1uF, or 1uF?), and reasonable on DC voltage readings. It's unfused on the current input, so I never use it for high current systems - that's just asking for trouble. For high current stuff, I borrow the high quality multimeters (with all the bells and whistles, like min/max hold, counters, and such) from work, but I can't remember the last time I needed to do that. I don't think buying a quality (expensive) multimeter would be a bad idea, and you're absolutely right about them lasting a LONG time (with proper care), but also don't think that it's necessary to buy something like a Fluke 289, BK Precision 393, or 121GW straight out of the gate.

I whole-heartedly agree with you about reading and following your equipment's specs! That's what I was hoping to convey with the "know your tools' limitations" bit.

Do you have a link to whatever kit you bought for the HF upconversion?


Reed


Re: uBITX v3 programming #arduino #ubitx

Chris Cancilla
 

I saw Dave Cassler on YouTube set up the mic and PPT on a pen cap.  It does work.

One question y'all.
The heatsinked transistors towards the back get hot in standby?
Do I need to find a fan of some kind for them?

___________________________
 
--
 
   Christopher E. Cancilla

  •– –  ••••–  –•–•  •  –•–•

     W4CEC.com

        678-371-5031  SMS / Cell
 
 



On Sun, May 17, 2020 at 8:27 PM Rick Price <rickprice48@...> wrote:
Chris,
Good job! You would not believe how much trouble that little 4.7k resistor has caused over the last 3 years!  Glad it's all working now.
 
Rick
KN4AIE
 
 


From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Chris Cancilla
Sent: Sunday, May 17, 2020 8:22 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBITX v3 programming #arduino #ubitx

Actually, all I did was add the 4.7 km resistor between the yellow and blue wires on the Arduino cable ribbon and that put the voltage where it needed to be. Then I made sure that the push to talk button that came with the kit was jumpered between the yellow and red wires on the tuning knob. So now I have access to all the bands and all the frequencies.

On Sun, May 17, 2020, 7:47 PM Evan Hand <elhandjr@...> wrote:
I would clarify what Christopher is saying in that the PULLUP RESISTOR and 3.5 mm plug needs to be installed.  The key itself is optional.

73
Evan
AC9TU


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: uBITX v3 programming #arduino #ubitx

Rick Price
 

Chris,
Good job! You would not believe how much trouble that little 4.7k resistor has caused over the last 3 years!  Glad it's all working now.
 
Rick
KN4AIE
 
 



From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Chris Cancilla
Sent: Sunday, May 17, 2020 8:22 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBITX v3 programming #arduino #ubitx

Actually, all I did was add the 4.7 km resistor between the yellow and blue wires on the Arduino cable ribbon and that put the voltage where it needed to be. Then I made sure that the push to talk button that came with the kit was jumpered between the yellow and red wires on the tuning knob. So now I have access to all the bands and all the frequencies.

On Sun, May 17, 2020, 7:47 PM Evan Hand <elhandjr@...> wrote:
I would clarify what Christopher is saying in that the PULLUP RESISTOR and 3.5 mm plug needs to be installed.  The key itself is optional.

73
Evan
AC9TU


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: uBITX v3 programming #arduino #ubitx

Chris Cancilla
 

Actually, all I did was add the 4.7 km resistor between the yellow and blue wires on the Arduino cable ribbon and that put the voltage where it needed to be. Then I made sure that the push to talk button that came with the kit was jumpered between the yellow and red wires on the tuning knob. So now I have access to all the bands and all the frequencies.


On Sun, May 17, 2020, 7:47 PM Evan Hand <elhandjr@...> wrote:
I would clarify what Christopher is saying in that the PULLUP RESISTOR and 3.5 mm plug needs to be installed.  The key itself is optional.

73
Evan
AC9TU


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: uBITX v3 programming #arduino #ubitx

Chris Cancilla
 

Thanks Evan, this is exactly what I needed. Mine did not have all this information in it. Now I can change bands and function so life is good. All I need to do is hook up the microphone and pull my antenna out of the shed and I should be able to run a test, but it may not be till next weekend because I have to work this week even though I am working from home.


On Sun, May 17, 2020, 5:51 PM Evan Hand <elhandjr@...> wrote:
I do not know of a v3 manual.  Here is a v4 which should be close:
https://ubitx.net/download/ubitx-v4-mini-manual/

73
Evan
AC9TU


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: Test equipment recommendations

Reed N
 

Hi Bob,

For home/hobby use, I have a Best DT-9205M. It's not a high quality multimeter, but it measures AC and DC voltage and current, resistance, and capacitance. It's good enough for order of magnitude capacitance (is this a 0.1uF, or 1uF?), and reasonable on DC voltage readings. It's unfused on the current input, so I never use it for high current systems - that's just asking for trouble. For high current stuff, I borrow the high quality multimeters (with all the bells and whistles, like min/max hold, counters, and such) from work, but I can't remember the last time I needed to do that. I don't think buying a quality (expensive) multimeter would be a bad idea, and you're absolutely right about them lasting a LONG time (with proper care), but also don't think that it's necessary to buy something like a Fluke 289, BK Precision 393, or 121GW straight out of the gate.

I whole-heartedly agree with you about reading and following your equipment's specs! That's what I was hoping to convey with the "know your tools' limitations" bit.

Do you have a link to whatever kit you bought for the HF upconversion?


Reed


Re: uBITX v3 programming #arduino #ubitx

Evan Hand
 

I would clarify what Christopher is saying in that the PULLUP RESISTOR and 3.5 mm plug needs to be installed.  The key itself is optional.

73
Evan
AC9TU


Re: Test equipment recommendations

Robert D. Bowers
 

Laugh!!!   I suggested a good meter because the ones I was thinking about had other useful functions like cap testing and better tolerance of spikes (plus the safety features you mentioned).  To that I'd add that multimeters as a general rule don't like HF (guess how I know)!  Some have a frequency counter function built in - but the models I've seen with that were limited in bandwidth - and as I'd learned, that maximum frequency and AC voltage IS the limit. Another suggestion to add - remember the specs and try to avoid exceeding them!

I'd forgotten the general coverage receiver.  Thanks for bringing that up.

As far as SDR, you can buy a bare-bones upconverter now that works pretty well, for not that much money.  I've got one - board and components only, but it's sensitive, rather good at rejecting signals above 30mhz, and doesn't seem to radiate much when used. (So far I've not seen any ghost signals from the upconverter - and I do watch for them.)

Bob

On 5/17/20 6:20 PM, Reed N wrote:
There's already a lot of good recommendations here, but thought I'd add my 2 cents.


Re: uBITX v3 programming #arduino #ubitx

Chris Cancilla
 

The CW Key NEEDS to be installed even if not used.
Thanks
My instructions did not have that.

___________________________
 
--
 
   Christopher E. Cancilla

  •– –  ••••–  –•–•  •  –•–•

     W4CEC.com

        678-371-5031  SMS / Cell
 
 



On Sun, May 17, 2020 at 6:28 PM Rick Price <rickprice48@...> wrote:
Chris did you install the 4.75k resistor? Without it the radio may cycle or stay in CW mode  See page 4 of the mini manual.  Also function settings on page 16.  Hope this helps!
 
Rick
KN4AIE
 


From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Chris Cancilla
Sent: Sunday, May 17, 2020 5:48 PM
To: BITX20@groups.io
Subject: [BITX20] uBITX v3 programming #arduino #ubitx

Well, I got the uBITX v3 assembled.  Put power to it, and it worked.
But, I am not a CW kinda guy.
It comes up on the display with ONLY CW: 7.150.000
I cannot find any manual or guide for programming.

HELP!!

--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: Better mic for ver 6.1

AA9GG
 

On some runs of the Baofeng mics, the little hole in the case for the mic is in the wrong spot!  Open it up and drill the hole in the correct spot (you'll see it).  My mic went from crappy to sounding GREAT!

On Wed, May 13, 2020 at 9:30 PM Curt via groups.io <wb8yyy=yahoo.com@groups.io> wrote:
Les

My v4 did not come with an assembled mic, so I found a kenwood speaker mic and wired a new connector on it.

Possibly your mic element may be okay, but have lousy material over it. Maybe I read here that some have modified those microphones?  also evaluate your output power. First check your cw output level. Your voice won't reach that level since an ordinary power meter responds too slow. But needle should dance significantly off of zero when you are getting adequate drive. See if your mic is delivering adequate audio. It could even be padding over the element. You may need to experiment,  ordering a new mic may not necessarily solve it.

Curt wb8yyy



--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com


Re: uBITX v3 programming #arduino #ubitx

Rick Price
 

Chris did you install the 4.75k resistor? Without it the radio may cycle or stay in CW mode  See page 4 of the mini manual.  Also function settings on page 16.  Hope this helps!
 
Rick
KN4AIE
 



From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Chris Cancilla
Sent: Sunday, May 17, 2020 5:48 PM
To: BITX20@groups.io
Subject: [BITX20] uBITX v3 programming #arduino #ubitx

Well, I got the uBITX v3 assembled.  Put power to it, and it worked.
But, I am not a CW kinda guy.
It comes up on the display with ONLY CW: 7.150.000
I cannot find any manual or guide for programming.

HELP!!

--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: CAT with a uBITX v3

AndyH
 

Peter,

   I'm using a V3 with CAT.  As others have said, the USB connection is the one on the Arduino Nano.  I'm using the KD8CEC firmware.  It works great with WSJT-X and Winlink/Winmoor.  I'm using this cable inside the cabinet to bring USB to the back:  https://www.adafruit.com/product/3318

   73, Andy, KG5RKP


On Sun, May 17, 2020 at 05:41 AM, Peter LB0K wrote:

Hallo, can someone help an elmer prepare for new questions.

This may well be a question answered many times before!
But it does no harm to ask again esp. as a search gave too many possible answers.

Where / how does one attach an external PC for CAT control. 

Either via a USB or an RS232 serial connection?

Peter


Re: Test equipment recommendations

Reed N
 

There's already a lot of good recommendations here, but thought I'd add my 2 cents.

I am in the fortunate position of having access to decent test equipment via my work when needed. However, I rarely actually take advantage of this, as for most hobby stuff, I can make due with the hobby grade stuff I have at home. One of the most important skills as a tinkerer is to learn how your tools work, so you can use them to their full potential, but perhaps more importantly, so that you know your tools' limitations and either work around them, or know when to buy better tools.

The Internet is an extremely valuable piece of "test equipment". If you look around here, or any of the other numerous radio forums, you'll find tons of examples of people describing basic symptoms, which others have already encountered, and can suggest fixes for, without ever using a physical diagnostic tool. However, the Internet by itself is also very limited in what it can test, so if you have an uncommon or non-obvious problem, it can't help much without additional test tools.

A cheap ($10-20USD) multimeter is by far the best testing per dollar investment. The one I have at home is known to be somewhat inaccurate, but has been good enough for diagnosing my hobby stuff for many years now. The continuity buzzer is probably the feature I use most anyway, to find shorts or opens where they shouldn't be. You can spend hundreds on a good multimeter, but do you REALLY need values accurate to 5 digits, or can you get by with 1-2 digits and a little error? You might need the accuracy if you're doing matching for a mixer, or precision resistor measurements, but most of the time I suspect not. The main thing to be careful with on the cheap end is high voltage or current, since many cheap models skimp on safety features like fuses. If you're working QRP or microcontroller electronics, this shouldn't be a big problem, but if you're working on high power rigs, then you'll want to make sure your multimeter has the proper fuses and isolation.

A SWR/power meter is useful for every-day operation. I have one built into my antenna matcher, and use it so much that I hardly think of it as test equipment, even though it obviously is. While an antenna analyzer can help you with SWR (discussed below), the forward power meter part lets you measure your actual output. Turns out SWR doesn't matter if your transmitter isn't actually outputting anything!

For general RF detection, an LED and a diode make for a super cheap indicator. Take a look at https://www.youtube.com/watch?v=V5SMF9p-4Q0 for example.

A dummy load is also piece test equipment I often take for granted. It's great for verifying transmitter stuff without actually broadcasting (appreciably), can be used in conjunction with a power meter to verify full power output without worrying about SWR, and if you have another radio, the leaked power on my dummies is often large enough to be detected by an adjacent receiver for further validation.

For radio use, it's a toss up for me if the next best investment is an oscilloscope, or a network/antenna analyzer. If you're planning on doing lots of antenna design or tweaking, then the analyzer would serve you better. If you're planning on spending more time working on rigs or other electronics, then the oscilloscope probably is the better choice. Of course, if you can afford both, then even better.

For oscilloscopes, as mentioned by others, the key is to have enough bandwidth for the signals you actually care about. The DSO138 you mentioned isn't necessarily a bad choice, as long as all of your signals of interest are in the audio frequencies, or are slow-ish digital (like Arduino stuff usually is). It's low price is attractive, but it's actually significantly more expensive in Hz per dollar than the "real" entry level oscilloscopes out there (200kHz/$10 for the cheapest DSO138 kit I see = 20kHz/$1, vs e.g. Hantek 2C42's 40MHz/$104 = 385kHz/$1), and is not at all competitive in performance. I have a XMEGA-based 200kHz (2MSPS) oscilloscope that I bought a number of years back, and it definitely has helped me solve problems that my multimeter just can't. Having even a 200kHz time domain can be incredibly useful, so if you have a tight budget, something like the DSO138 could be worth while. However, for analyzing RF, you'll need an oscilloscope that has a much larger analog bandwidth. The uBiTX IF goes up to 75MHz (officially, more if you ask the Si55351 to :P), so if you plan to work on the uBiTX's RF chain at all frequencies, you should consider buying a scope capable of ~75MHz analog bandwidth. As Robert mentioned, DSOs are sometimes advertised with their sampling frequency, rather than analog bandwidth. Shannon/Nyquist tells us we need at least 2x sampling for a given frequency, so you'd need an absolute minimum of 150MSPS to get 75MHz analog bandwidth measurements, but realistically you should aim for higher samples per second so that you can actually see the shape of the wave. Analog oscilloscopes don't have discrete samples, so as Ashhar pointed out, you can use them at higher frequencies - they'll just measure lower amplitudes than actually are present past their designated bandwidth. I would agree with Bill, and advise against purchasing anything on eBay that's not listed as being in working condition with pictures of sample traces, unless you're ready to spend time diagnosing and fixing it yourself, which will be particularly difficult if you don't already have a working oscilloscope. Randy's suggestion of looking at hamfests is a good one.

For the antenna analyzer, the NanoVNA you mentioned is a great tool for the money. It's capable of all the stuff the more expensive units are (e.g. MFJ's SWR-584C, or RigExpert offerings), but the NanoVNA has a bit steeper of a learning curve than those more expensive options too. K7TRF wrote up a nice short comparison recently over at https://forums.qrz.com/index.php?threads/antenna-analyzer-so-many-choices.689265/#post-5335185 . One thing to watch out for with the NanoVNA specifically is all of the clones. I'd strongly recommend buying directly from one of the NanoVNA's developer's links (such as hugen79 or flyoob
) to ensure you get one that doesn't take any shortcuts, and directly benefits the parties responsible for the tool development.

Once you have most of the equipment above, an SDR would probably be my next recommendation. The normal RTL dongles won't work at HF (though you can find some RTL dongles with HF upconverters built in), but there are a good number of options in the ~$100USD range. There are tons of things you can do with SDR, but as a test tool specifically for the uBiTX, I've found it most useful for calibration of the oscillator, and verification of signal output in various modes. They can also work as a windowed spectrum analyzer, useful for finding unwanted harmonics or spurs, or measure relative power output.


Reed


Re: uBITX v3 programming #arduino #ubitx

Jim WB2LHP in MI <jmarco1955@...>
 

You should also be able to change modes via the menu...

Virus-free. www.avg.com


On Sun, May 17, 2020 at 5:47 PM Chris Cancilla <Chriscancilla@...> wrote:
Well, I got the uBITX v3 assembled.  Put power to it, and it worked.
But, I am not a CW kinda guy.
It comes up on the display with ONLY CW: 7.150.000
I cannot find any manual or guide for programming.

HELP!!

--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC


Re: uBITX v3 programming #arduino #ubitx

Jim WB2LHP in MI <jmarco1955@...>
 

Try cycling the PTT line and see if it switches to LSB or USB...

Virus-free. www.avg.com


On Sun, May 17, 2020 at 5:47 PM Chris Cancilla <Chriscancilla@...> wrote:
Well, I got the uBITX v3 assembled.  Put power to it, and it worked.
But, I am not a CW kinda guy.
It comes up on the display with ONLY CW: 7.150.000
I cannot find any manual or guide for programming.

HELP!!

--

__________________________
Chris Cancilla, W4CEC
Raleigh, NC