Re: Bitx40v3 CAT Control firmware?

Bill Cromwell

Hi =Vic=

It's much the same as VOX or semi-break-in or full QSK. It's a personal requirement driven by personal preferences. In my experience each and every ham is at least a little bit different from every other. Some of the differences are quite a contrast! I don't use CAT because none of my radios have ever cooperated with a computer but now I have one that will. I will eventually get around to trying it. Maybe I will discover that I can't live without CAT :) I tried FT-8 and rejected it out of hand. But I also tried CW and I still like it:) I even enjoy SSB and PSK-31 of all strange things. Have =you= tried CAT? If you did then you will be able to tell us why you do or do not like it:) The rest of us are on our recognizance.


Bill KU8H

On 08/05/2018 06:17 AM, Vic WA4THR via Groups.Io wrote:
Just curious why CAT control is seen as a requirement, When I started
with PSK31 I was using an older rig and the only connection to a
computer was via a SignaLink that provided audio in/out and PTT derived
from a VOX circuit in the SignaLink. Others keyed the rig with some
other output line from the computer off a serial port. Almost all the
digital modes (save RTTY) were on "fixed" frequencies with tuning done
by just varying the tones supplied/received in the audio passband of
that frequency. Logging was easy since the frequency never changed. So
what is the value of CAT control?

bark less - wag more

Re: Harmonic performance - SSB vs CW



If there are pin compatible Omron relays would it make sense to solder a set into a stock board that has been already characterized on a spectrum analyzer and see what effect the better relays have? It seems a reasonable expense for an experiment that may tell us things.


Re: uBITX: new build #ubitx

hirosmb <hirosmb@...>

Cool! I like it.

// hiro, JJ1FXF

2018/08/05 4:05、Jim Reagan <jimreagans@...>のメール:

Oops, the photo!!!

Re: Harmonic performance - SSB vs CW

James Lynes

For now kit up and offer an external filter add-on capable of handling the output of the finals being powered from up to 24v.

Fix the problem on a v5, v6,... board.


Re: One question only...


To the best of my knowledge, the Ubitx is legal if built stock without mods.  In particular ... mods boosting Mic gain on frequencies above 20 meters may cause spurs.  So even with mods, you've still got a legal 20, 40 and 80 meter radio.  Still one heck of a deal for the price.

Re: Harmonic performance - SSB vs CW


I discovered this problem early on and replaced the entire filter network with a QRP outboard network from another QRP radio I got off eBay (picture attached, also has other features for power and SWR and separate receive antenna port).  I use 1-of-N binary decoding like you suggest with a simple mod of the code.  I did this, though, primarily because I wanted to investigate using the uBITx on 160 and 6 meters too… but it cured spikes seen at other parts of the spectrum too. I may have the spectrum pictures from my Spec An somewhere that I can share. Using a daughter card is the way to go in my opinion because it allows experimentation beyond the 80-10 meter existing platform.  It could be made much better/ less power hungry with latching relays.


From: [] On Behalf Of Ashhar Farhan
Sent: Saturday, August 4, 2018 11:22 PM
Subject: Re: [BITX20] Harmonic performance - SSB vs CW


I have been following this thread, I have to add three things here :


1. Unike commercial products where no criticism is encouraged, ubitx is an open source radio, So, Warren, we all do want to hear and correct whatever goes wrong with this design. We all hope it gets bette with time. As Linus Travolds reminds us "Given enough eyeballs, all bugs are shallow".


2. The reason for the convoluted relay system is that we ran out of pins on the Arduino to directly switch the LPFs. Instead, we should use a 1-of-N decoders to drive the relays, increase the number of LPFs to six (from the current count of 4). Bad economics. It will also lead to a differently sized board as it will be difficult to fit two more relays AND decoder onto the same sized board. This will mean putting the people like Sunil out of business until they retool their boxes. 


3. Another possibility is to split up the design into multiple boards. It makes sense for the solder happy hams, it is  nightmare for those who'd rather ragchew and chase dx than get under their race car's hood for months.


Given that there are non-technical considerations and a few thousands of ubitx already in use, we must be careful to not break backward compatibility of these radios. Any sugggestions?


- f


On Sun, Aug 5, 2018 at 8:45 AM, Gordon Gibby <ggibby@...> wrote:

Jerry wrote:

"Looks to me like a good part of the problem is board layout.
Each LPF is fed from a relay, then has a trace from the far side of the LPF
coming back right under the LPF to get back into the other set of relay.contacts."


The photo of a dpdt relay that I enclosed was just the only internal image I could find.   I haven't found one of the actual relays used.


Enclosed is a backlit photo to show theground plane --- which covers just about everything --- and the LONG return trace  from the other end of the filter.


I don't quite know how to "read" the rigol display that Warren put up, but since some of his bands hit the -43 dBm requirement of 97.307(d) (first part):  (d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission.​....


then I'm guessing that a few dB more isolation and more bands would "pass".    The return trace comes nicely close to lots of components!   The ground plane is available almost below everything.    drilling through and adding a tin metal shield between the return trace and the remainder of the circuit with a couple of solders to the ground plane might add some dB of isolationwithout having to tear into the relay.   It is probably advisable to run the "shield" tin metal right up to the relay in hopes of possibly even improving by a tiny bit the isolation there.   dunno.   brighter people than me, and those with the nice spectrum anallyzers (or Ashar) might have to figure this one out!





From: <> on behalf of Jerry Gaffke via Groups.Io <>
Sent: Saturday, August 4, 2018 10:07 PM
Subject: Re: [BITX20] Harmonic performance - SSB vs CW


Looks to me like a good part of the problem is board layout.
Each LPF is fed from a relay, then has a trace from the far side of the LPF
coming back right under the LPF to get back into the other set of relay.contacts.

One possible solution:
Rip out that return trace on each of the LPF's.
Add a set of straps at the far end of the LPF's to select one of them for connection to the antenna jack.

I haven't been following closely, has anyone reported any numbers on just how bad
these harmonics are during SSB ops?   


On Sat, Aug 4, 2018 at 06:28 PM, ajparent1/KB1GMX wrote:

Using two of the current ones would yield a very good result as on would be literally physically
on the other side of the filter for a good layout.




…_. _._

Re: One question only...

Jack, W8TEE


I kinda agree on one hand, and as much as I hated the code exam (Novice in 1954) and vowed I would never do CW again after I got my General (1955), but something changed after I retired. 1955-2009 was pretty much AM-SSB, but now I find I am really enjoying CW. That Farhan put both modes into the µBITX is one thing that attracted me from the outset, when I bought the BITX-40.

My goal was to provide an inexpensive means by which young hams on a lawn-mowing budget could get on the (HF) air. (Far too many get their Tech, buy an HT for 2M, and shortly thereafter drop out, and I understand that completely.) My first attempt to do something was the Forty-9er (QST, March, 2016). Alas, that was CW only and very few newcomers seem to be interested in CW, and that's a real step in the dumbed-down process. When I surveyed my club members, 87% said they wanted to learn CW. Yet, when I offered to teach a class, everyone's sock drawer suddenly needed rearranging.

That said, the µBITX still is a great avenue for someone to venture away from VHF/UHF into HF at a very reasonable cost. The stock µBITX is what I call a "semi-kit" and any licensed ham should be able to put a stock version together. Ian and a host of others have collaborated to add a touch-screen (Nextion) display, but still shoehorn it into a Nano. Jim Sheldon and his group have taken it a step further by adding additional features, too. Our JackAl board also extends what the µBITX can do. These extend the capability and functionality of the µBITX and make it a better rig...but you don't have to.

The point is, the µBITX is a great entry-level rig for someone on a limited budget or as a second rig for portable work. However, it is also capable of being a learning device, too. Anyone who reads the posts here and explores is going to be a more effective user of the µBITX. That's a good thing.

At your next club meeting, look around. Mine's getting a little long in the tooth and, frankly, I don't have an effective plan to change that. Clearly, we need young blood in this hobby and, if cost is any barrier to entry, the µBITX can be our ally, provided we "sell it" correctly. It's a semi-kit that almost anyone can put together, use, and learn from, and that should be how we view it.

Jack, W8TEE

On Sunday, August 5, 2018, 3:15:54 AM EDT, Christopher Miller <djmalak2k6@...> wrote:

What I get out of this is sad. I was one of the last hams in the US to actually have to learn Morse code to be able to have HF privileges. 

To me it seems the hobby is so dumbed down that if you expect to buy an unfinished kit and want to treat it like a Kenwood you probably are in over your head.

This from my understanding was grown out of a desire to in fact provide people in places and economic situations to be able to use hf. 

Find a spectrum analyzer or a person who can if you want to build your own rig. 


Re: Harmonic performance - SSB vs CW


Yes… Si5351 should be on the main board.


From: [] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Sunday, August 5, 2018 12:00 AM
Subject: Re: [BITX20] Harmonic performance - SSB vs CW


Going forward, I for one would be fine with plug-in LPF's on a rig in this price range.
Should have some way for the Raduino to sense what board is installed.

Those that want electronic switching could add some optional mezzanine board that plugs 
into that same socket, an i2c bus controlling all the relays.

If you remove the relays we have now, might be possible to use those holes
to convert current boards to this scheme.
But hacking current boards to have straps at the output side of the four
bandpass filters is easier, and solves both the trace problem
and the issue of isolation through the relays.

Allison has been recommending band specific filters in place of the 30mhz low pass filter
in front of the first mixer.   But I like how simple the rig is now, and would look first for reasons
not to raise the 45mhz IF frequency some.  Alternately, just call it quits at 20 meters.

Need something better than 2n3904's in many positions.
Perhaps an extra driver stage.
Si5351 should drive the mixers harder.
Si5351 might want to be on the main board.

Jerry, KE7ER



…_. _._

Re: One question only...

Gordon Gibby <ggibby@...>

Low pass filters $4.60 ea if necessary ( I have one to use a bitx40 on 80) 

Likely some simple series tuned  filter would add enough additional dB all by itself.  Variable cap, single section , tune most bands with one circuit.    This is ham radio....


On Aug 5, 2018, at 09:20, "davedt1e@..." <davedt1e@...> wrote:

To the best of my knowledge, the Ubitx is legal if built stock without mods.  In particular ... mods boosting Mic gain on frequencies above 20 meters may cause spurs.  So even with mods, you've still got a legal 20, 40 and 80 meter radio.  Still one heck of a deal for the price.


terry hughes

Can i use a dynamic mike with 400 ohms measures resistance with the ubitx or the bitx40

i have not ordered yet - i am trying to make up my mind which one to buy


ubitx menu

terry hughes

Is there a document describing the ubitx menu structure


Humble suggestion future Ubitx versions #ubitx


I offer this suggestion for what it's worth, and with full knowledge that I barely know what I'm talking about.

It seems that the issue of spurs above 20 meters has been a source of endless discussion and confusion...not to mention a great deal of headache for those trying to troubleshoot.

I understand that Farhan wanted to keep this kit at around a hundred bucks.  But I would suggest biting the proverbial bullet and filtering for 10 meters.  Perhaps add a smidge of Mic gain as well, and calling it done.  So the price creeps up near 200 bucks.  That is still within the grasp of the kid mowing lawns...or the humble poor scooter mechanic like me ;-)

Market it for 10 20 40 and 80 meters and it's still by far the most incredible deal to ever hit the ham radio world.

I understand that this kit is for experimenters and consider myself amongst them, albeit as a beginner.  But the sheer popularity of it has inevitability drawn a lot of beginners who just want to get on air.  That's not a bad thing so it might just be easier to satisfy that niche as well.

Loving my v3 ubitx and almost ready to take my general exam.  Thanks to Farhan and all the other contributors.

Re: One question only...

ajparent1/KB1GMX <kb1gmx@...>


There is no FCC approval process for kits and home brew.  It is the Amateur radio operator
to assure its compliance.  

There is enough question as to do all or some not meet the numbers to say the sample size
for those known to have issues is small enough to be an uncertain.


Re: Harmonic performance - SSB vs CW

ajparent1/KB1GMX <kb1gmx@...>


Any of those I'd use at RF will not fit the board.  At over 5$ each its someone elses choice.

I along with several other have found the layout of the board to be problematic.  So 
just replacing relays is not a simple fix. 

Sarcasm alert:
If I say the problem is systemic will there be a posting to replace the "systemic"
with something better?  ;)


Re: One question only...

Lawrence Macionski <am_fm_radio@...>

Hi All-
Since very few of us have spectrum analyzers, there are ways to reasonably verify you're transmit signal will slip under the "illegal" problem. My first and last OO notice came in 1966 - I was driving my 6V6 single tube CW transmitter tuned via a #47 pilot lamp and received a notice my 2nd harmonic was being heard 90 miles away. (7154 x 2= 14308) I found tuning my pi-network, I could easily reduce a lot of 2nd harmonics just by backing off a few watts. I wound up homebrewing an antenna tuner and all my problems were gone.. A telephone, a buddy and his receiver 2 miles away confirmed it. An antenna tuner at the transmitter is good for harmonic suppression.

Don't forget that wattmeter.. even with a dummy load will show all kinds of power output - clean or dirty...Remember that Backing down a few watts, will never be heard on the other end of a QSO and can render a cleaner signal. If your going to strive for more power strive for a clean signal as well..

Re: Harmonic performance - SSB vs CW

ajparent1/KB1GMX <kb1gmx@...>

Better filters, external, with larger toroids can't hurt.  Your results would be worth seeing.

For those that want to try it... what filter and is there a reliable vendor?


Re: Harmonic performance - SSB vs CW

ajparent1/KB1GMX <kb1gmx@...>


Its that capacitance and also common mode via the magnetic frame that compromises the filter.

The best combo for inexpensive relays is input bus, switching, filters, switching, output bus.
The idea is separate relays at opposing ends of the filters.  The relays can be 5V or 6V units
wired in series.  I've done this before and with a good ground plane it easily exceeds the need.

However it need to be done twice.  At the input of the amplifier its an easy task to eliminate
a large amount of unwanted stuff.    Its easy to have wide tuning RX but limited bands TX
that is clean then.  If we do not put square waves and wide band spurs into the amp it
helps the IMD and reduces what we get out.

Two things helpful to the unequipped is a simple SWR detector and a RF out detector.
that and a few built in measuring points.  Adding protection to input on the NANO would
prevent some pain seen. as well as relocating the 4.7K to the Raduino board.


Re: any tips for debugging RFI issue? #ubitx-help

ajparent1/KB1GMX <kb1gmx@...>


Putting the wire in what is likely an aluminum gutter made it longer and likely not a bad thing.
Any metal you have available can be helpful!


Re: any tips for debugging RFI issue? #ubitx-help

Diane Bruce

On Sun, Aug 05, 2018 at 07:43:28AM -0700, ajparent1/KB1GMX wrote:

Putting the wire in what is likely an aluminum gutter made it longer and likely not a bad thing.
Just make sure the eavestrough is well bonded. Oxides are wonderful

Any metal you have available can be helpful!


- db@... db@...

Re: One question only...

Doug W

Since we're on the topic of FCC regulations, while I have never seen an official statistic, I would venture to guess well over 90% of US hams violate 97.313(a) every single time they transmit.