Topics

BitX-40 mobile #bitx40 #ssb


Robert D. Bowers
 

I've finally gotten the noise problem with my BitX-40 down to where it's not too bad, and I think with some additional work, I can eliminate the little is left.

My setup:  BitX-40 with homemade bugcatcher antenna (total height about 7 ft, much more and I get clobbered by tree limbs), in a GMC Safari van (1996).  The audio runs into a JPS NIR-10 which provides DSP noise filtering, strong AGC, and greater audio.

When I first started, I was having a real fit with alternator whine AND very loud spark plug noise when the engine was running - making using my BitX-40 impossible except if I stopped and turned off the motor.

I found that I could eliminate most of the alternator whine with a big iron-core choke, but the ignition noise was horrendous.  It seemed to come in through the antenna, but I found out that wasn't the case - putting filtering on the coax did nothing.  The choke made some difference, suggesting that the noise was actually coming from elsewhere.

I couldn't find the source, so I decided to change from connecting to the harness for power, to going to the battery.  I set up and installed a power lead running from the battery connection on the external fusebox (which has a 3/8 copper cable running to the battery) - the lead had a strong noise filter built in, and I used some old RG58 coax to supply power (with a fuse and another choke at the battery).  While running this lead, however, I discovered that the cover for the motor was actually fiberglass, and for shielding they'd just put heavy aluminum foil on the inside.  I also found where they'd attached a grounding point, but they grounded the cover through the wiring harness - the actual ground was located (I think) at the internal fuse box, a couple of feet away or so.  I added a nice thick copper ground straight from the ground point to the frame of the van.

This eliminated the original problem, but a new one cropped up.  The alternator whine was back but only in the NIR-10 (although not very loud) - even with the radio turned off, the NIR-10 would pick up the alternator noise and a tiny bit of the spark plug noise whenever I connected it to the radio.  I added additional ground wires to the Bitx40, and so far have done just about everything I can think of.  I'm going to change the power wiring for the radio, so that both the filter and the BitX-40 run from the same connection, to see if I can completely eliminate the noise.

The points to take from this are:
(1) make sure ALL of the shielding is in place and properly bonded, with shortest possible paths to ground, if you want to eliminate ignition noise.  One crazy bad connection can really screw things up!  (Even if it was grounded, taking the ground from the wiring harness rather than from the nearest part of the frame was not a good idea!)
(2) You should tap the 12v at the battery, a nice very low impedance point - tapping in at the fuse box may introduce noise.
(3) Be aware of lead dress - it can be very important.
(4) Ground, ground, ground!!!  adding additional ground wires internally helped, but the biggest improvement came from adding the short (6 inch) piece of very thick copper wire from the frame (steel) to the grounding point on the engine cover.

I will add a final question.  The Raduino code is version 1.20, the tuning is via a 10 turn pot, and when you hit the endpoints of the pot, the Raduino starts counting up/down, changing the section of the spectrum covered by the pot.  I'd like to mod that so that I have to push a button to enable the band-section change.  I'd also like to have frequency lock.  I haven't found instructions for that Raduino and the code - how to manipulate it.  Where can I find instructions, and whose version might it be?

Thanks - and I hope these tips (and telling about my experiences) help someone!

Bob
N4FBZ


Vic WA4THR
 

Well done on the BitX40 mobile. I was, perhaps, lucky that only the alternator whine had to be handled in my case.

There is a hack on line for replacing the "end of rotation" frequency jumping with pushbuttons. Basically it adds resistors with pushbuttons to short them out to simulate that the max or min pot resistance has been reached. If you haven't done so already, upgrade to Allard's sketch. I think the latest for an unmodified BitX40 is 1.28 and with a very few simple and well illustrated additions such as a single resistor and lead to the raduino to detect when in transmit it allows A & B VFO selection, frequency scanning, VFO lock, etc. It also pretty much eliminates tuning clicks and allows you to adjust the span covered by the tuning pot.

You can get it at https://github.com/amunters/bitx40

Take a look at his well-written and illustrated notes where he shows what simple mods are needed for the specific features you want, but it runs fine with no mods at all.

=Vic=


Jerry Gaffke
 

One thing  Allard's sketch does that the stock code does not do
is avoid random jumps in frequency of 50hz due to noise in the signal from the tuning pot.
Gets old quick.  So once the rig is working, update to Allard's sketch.

Jerry


On Mon, Feb 11, 2019 at 02:50 AM, Vic WA4THR wrote:
Well done on the BitX40 mobile. I was, perhaps, lucky that only the alternator whine had to be handled in my case.

There is a hack on line for replacing the "end of rotation" frequency jumping with pushbuttons. Basically it adds resistors with pushbuttons to short them out to simulate that the max or min pot resistance has been reached. If you haven't done so already, upgrade to Allard's sketch. I think the latest for an unmodified BitX40 is 1.28 and with a very few simple and well illustrated additions such as a single resistor and lead to the raduino to detect when in transmit it allows A & B VFO selection, frequency scanning, VFO lock, etc. It also pretty much eliminates tuning clicks and allows you to adjust the span covered by the tuning pot.

You can get it at https://github.com/amunters/bitx40

Take a look at his well-written and illustrated notes where he shows what simple mods are needed for the specific features you want, but it runs fine with no mods at all.

=Vic=


Robert D. Bowers
 

Fall back plan -  I have very little time - I'm trying to come up something for when I'm driving (for me, dead time) that will help me to relax - and I like to chat with people.  I spent precious time getting this far... and need to get the thing going so I can actually talk with people instead of fighting with hardware.  That worries me... what do you mean?  I do NOT want to have to spend more time trying to diagnose some obscure problem (like I did with the ignition noise)!

(Before people start the "you gotta learn something!!!" line, I'm a doctoral candidate and I have to spend almost ALL of my time LEARNING.  I need RELAXATION time - and for me, troubleshooting and fixing are NOT relaxing at all!  {Building and creating, on the other hand, IS!})

I've had this BitX for several months - it was a gift, because I've always wanted a mobile 40m and never could afford one (even a BitX is out of my price range - and I have to scrounge parts if I want to try to build anything).  Unless the newest version of the board is actually at least a year old, I doubt I have that version.

Yeah... I did forget to mention the transmatch.  While I'd rather have a "T" match as IMO it would be more likely to efficiently transform the impedance to 50 ohms without a lot of losses, all of the variable caps I have are of the grounded rotor style, and I don't have the proper insulators and so on to use them. 

I built a small Pi section matcher (with variable caps and variable coil).  It does work, but I do think I'm having a problem with loss of signal.  If I could find a large toroid I have ("buried somewhere") that is good for HF, I'd make a matching transformer to take care of the mismatch at SSB frequencies I plan to use (those for qrp or BitX - I don't like fighting with alligators!).  The largest toroid I have of the right type is rated at something like 5 watts maximum.  I hoped to go to Orlando this year and find a more appropriate toroid, but... when you're broke even gas and entry fee is a problem.

Do you know how to identify whose version this is... and where I might find a simple instruction set?  I can calibrate (calibration button), and I think it will do other things, but haven't experimented much with that.  The instruction set I've found was for version 1.28.

On 2/11/19 1:30 AM, engstr@... wrote:
Bob 


https://github.com/afarhan/bitx40   is one of the Many !  versions of the software.  They can all be found by google searches with Github and Bitx40 in the string.

There are the Allard modifications to look at .   There are two versions , the bare one and the one requiring some rewiring (latter gives you indep VFO and CIO )

You have to have a fall back plan if you try to do a download to the Raduino and it locks half way.  A word to the wise .

THere  is no known implementation supporting an encoder for this machine  which is prolly what you were hoping for.

You did not mention how you did the matching into such a small antenna for  40 m ??

Beware the Bitx40s as being delivered a the moment do not agree with the schematic - as of a few weeks ago. The changes I know of  are in the modulator area.


regards,


Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885, 
Telephone Whangarei   022  691 8405
e: Engstr@...



----- Original Message -----

To:
<BITX20@groups.io>
Cc:

Sent:
Sun, 10 Feb 2019 21:11:54 -0800
Subject:
[BITX20] BitX-40 mobile #bitx40 #ssb


I've finally gotten the noise problem with my BitX-40 down to where it's not too bad, and I think with some additional work, I can eliminate the little is left.

My setup:  BitX-40 with homemade bugcatcher antenna (total height about 7 ft, much more and I get clobbered by tree limbs), in a GMC Safari van (1996).  The audio runs into a JPS NIR-10 which provides DSP noise filtering, strong AGC, and greater audio.

When I first started, I was having a real fit with alternator whine AND very loud spark plug noise when the engine was running - making using my BitX-40 impossible except if I stopped and turned off the motor.

I found that I could eliminate most of the alternator whine with a big iron-core choke, but the ignition noise was horrendous.  It seemed to come in through the antenna, but I found out that wasn't the case - putting filtering on the coax did nothing.  The choke made some difference, suggesting that the noise was actually coming from elsewhere.

I couldn't find the source, so I decided to change from connecting to the harness for power, to going to the battery.  I set up and installed a power lead running from the battery connection on the external fusebox (which has a 3/8 copper cable running to the battery) - the lead had a strong noise filter built in, and I used some old RG58 coax to supply power (with a fuse and another choke at the battery).  While running this lead, however, I discovered that the cover for the motor was actually fiberglass, and for shielding they'd just put heavy aluminum foil on the inside.  I also found where they'd attached a grounding point, but they grounded the cover through the wiring harness - the actual ground was located (I think) at the internal fuse box, a couple of feet away or so.  I added a nice thick copper ground straight from the ground point to the frame of the van.

This eliminated the original problem, but a new one cropped up.  The alternator whine was back but only in the NIR-10 (although not very loud) - even with the radio turned off, the NIR-10 would pick up the alternator noise and a tiny bit of the spark plug noise whenever I connected it to the radio.  I added additional ground wires to the Bitx40, and so far have done just about everything I can think of.  I'm going to change the power wiring for the radio, so that both the filter and the BitX-40 run from the same connection, to see if I can completely eliminate the noise.

The points to take from this are:
(1) make sure ALL of the shielding is in place and properly bonded, with shortest possible paths to ground, if you want to eliminate ignition noise.  One crazy bad connection can really screw things up!  (Even if it was grounded, taking the ground from the wiring harness rather than from the nearest part of the frame was not a good idea!)
(2) You should tap the 12v at the battery, a nice very low impedance point - tapping in at the fuse box may introduce noise.
(3) Be aware of lead dress - it can be very important.
(4) Ground, ground, ground!!!  adding additional ground wires internally helped, but the biggest improvement came from adding the short (6 inch) piece of very thick copper wire from the frame (steel) to the grounding point on the engine cover.

I will add a final question.  The Raduino code is version 1.20, the tuning is via a 10 turn pot, and when you hit the endpoints of the pot, the Raduino starts counting up/down, changing the section of the spectrum covered by the pot.  I'd like to mod that so that I have to push a button to enable the band-section change.  I'd also like to have frequency lock.  I haven't found instructions for that Raduino and the code - how to manipulate it.  Where can I find instructions, and whose version might it be?

Thanks - and I hope these tips (and telling about my experiences) help someone!

Bob
N4FBZ


Robert D. Bowers
 

Thanks for the tip!  That's a great idea and eliminates the biggest issue I deal with in the radio... do you have a link to where I could find the information for that mod?  (That's a mod worth doing right away.)  I ran across and performed a mod to increase SSB sensitivity (removing c91 and c92) which made a big difference.  Most of the other mods... not ones I consider worth doing.

I may not change the version... the only thing I'd like to have is dial lock but can live without it.  All the other bells and whistles - not needed or even wanted.  The tuning clicks don't bother me, and I don't do CW (neurological issues make it unreliable).  The external filter I picked up a few years ago (for $5, although it needed a simple repair) handles AGC just fine plus adds DSP noise filtering. 

I rather hold to the KISS adage!

Bob

On 2/11/19 5:50 AM, Vic WA4THR via Groups.Io wrote:
Well done on the BitX40 mobile. I was, perhaps, lucky that only the alternator whine had to be handled in my case.

There is a hack on line for replacing the "end of rotation" frequency jumping with pushbuttons. Basically it adds resistors with pushbuttons to short them out to simulate that the max or min pot resistance has been reached. If you haven't done so already, upgrade to Allard's sketch. I think the latest for an unmodified BitX40 is 1.28 and with a very few simple and well illustrated additions such as a single resistor and lead to the raduino to detect when in transmit it allows A & B VFO selection, frequency scanning, VFO lock, etc. It also pretty much eliminates tuning clicks and allows you to adjust the span covered by the tuning pot.

You can get it at https://github.com/amunters/bitx40

Take a look at his well-written and illustrated notes where he shows what simple mods are needed for the specific features you want, but it runs fine with no mods at all.

=Vic=


James Lynes
 

Bob:

As Vic said take a look at Allard's code. I use v1.26.

With a ten turn pot you can set the TUNING_POT_SPAN to 300 to tune the whole band without jumping. Also set MIN_FREQ to 7000000UL, MAX_FREQ to 7300000UL, and START_FREQ to 7200000UL(or a freq of your choice).

James


Ted
 

On Mon, Feb 11, 2019 at 01:07 PM, Robert D. Bowers wrote:
the only thing I'd like to have is dial lock but can live without it. 

Hey, Bob.

Regarding a dial lock, my first build of a uBitx used one of these successfully. While I used a spare from work (which went to equipment we no longer have in service), this price seems reasonable on a student budget. There will be a little "cllick" and a trace of resistance each revolution, the physical item inside the knob responsible for that can be "removed" without loss of the brake action of that external tab. 

One way to install this is to put a trace of JB-Quick along the bottom rim of the knob base, fit over your POT shaft, and fix the set screw. Come back in 8 minutes and trim away the overflow of the adhesive while in plastic-stage with a flat razor, let stand another 10 minutes to harden fully and you'll have a nicely-functioning knob whose position you can easily lock down while driving.

While I like a nice, heavy knob with a finger indentation for across-the-band spinning of a tuner, the ability to avoid inadvertently QSY while driving is also very much appreciated! The uBitx required an additional SPST next to this, for function control though I don't think your Biix-40 needs that, does it? For my build, moving to a TFT display removed my desire for a locking knob but if I had a Bitx-40, I'd likely still be using this. 

Best of luck with it,

Ted
K3RTA

P.S. - Regarding torroids, I wound a 9:1 torroid to feed an experimental, top-of-fence hidden QRP antenna made with magnet wire. I think it was a T-50-2 (about 13-14mm across) and it's been loaded up with 30-40 watts of FT-8 and almost 100w of SSB.  It may be lossy at those levels but the wood fence hasn't lit up on fire, yet. Maybe the windings glow at night, I don't know.. I'll have to put the weather camera in that direction and see what happens when I load it up on 160  :o


Allard PE1NWL
 

On Mon, Feb 11, 2019 at 01:07 PM, Robert D. Bowers wrote:
the only thing I'd like to have is dial lock but can live without it.
Bob, software version v28.1 provides "dial lock" functionality.

73 Allard PE1NWL


Jerry Gaffke
 

A dial lock would be trivial to add to any of the firmware versions,
assuming you can find an IO pin to put a switch on.
Unfortunately, there aren't enough of them as it is.

Alternately, it might be sufficient to adjust the firmware such that tuning is locked
whenever the transmitter is used.  Subsequent unlock only occurs when the encoder
is moved a quarter turn or so, at which point the rig starts tuning normally again.
Tuning should not immediately jump off a quarter turn away, but instead slowly
start moving from where it had been locked.
This would not be quite so trivial as adding the switch, but easy enough.

A third possibility would be a double pole switch that shorts the encoder's two signal lines
to ground.   Ideally, the firmware that handles the encoder would be adjusted to only advance
the frequency on a rising edge from the encoder, avoiding false counts due to contact bounce.

Jerry, KE7ER


On Mon, Feb 11, 2019 at 01:07 PM, Robert D. Bowers wrote:
the only thing I'd like to have is dial lock but can live without it. 


Jerry Gaffke
 

That third possibility of disabling the encoder with a switch is not so good,
as it would prevent the use of RIT to adjust the receiver while locking the transmitter.


On Tue, Feb 12, 2019 at 06:12 AM, Jerry Gaffke wrote:
A third possibility would be a double pole switch that shorts the encoder's two signal lines
to ground.   Ideally, the firmware that handles the encoder would be adjusted to only advance
the frequency on a rising edge from the encoder, avoiding false counts due to contact bounce.


Vic WA4THR
 

The mod for improving the "galloping VFO' is described here:
https://dcasler.com/2017/03/17/bitx-40-fix-for-galloping-vfo/

Again, I really recommend uploading Allard's sketch, too. It really improves the operation of the BitX40 even if you just upload it and make no hardware changes at all.

=Vic=


Robert D. Bowers
 

Thanks!  That solves the (more or less) final issue I have with the radio that I'd take the time to deal with - exactly what I needed and wanted to know! 

I don't think I'm going to change the firmware, at least until I have a better grip on why people have warned to have a 'backup plan' - and that would be at least a year away as my 'school stuff' takes precedence.


On 2/12/19 10:00 AM, Vic WA4THR via Groups.Io wrote:

The mod for improving the "galloping VFO' is described here:
https://dcasler.com/2017/03/17/bitx-40-fix-for-galloping-vfo/

Again, I really recommend uploading Allard's sketch, too. It really improves the operation of the BitX40 even if you just upload it and make no hardware changes at all.

=Vic=