Date   
Re: K5BCQ uBITX Relay Switched LPF/BPF board

Kees T
 

You can also see, in the picture with the uBITX board, that the 2N3904's have already been pulled, waiting for the 2N2222A's ..............and other incremental improvements.  

73 Kees K5BCQ

Re: K5BCQ uBITX Relay Switched LPF/BPF board

Kees T
 

You can also  modify the existing filter for a faster roll-off which MAY catch enough of the 15m spur .....for instance. The plot labeled "1" is the original LPF, the other plot is the modified LPF.

73 Kees K5BCQ

Re: 80 Meters Harmonics Fix Proposal

Warren Allgyer <allgyer@...>
 

Got it Howard. And I agree with both the strategy and the necessary amount of improvement. On mine, a six dB improvement would make all bands legal for CW harmonics. That would be a nice solution for a CW only radio. Of course you must not use it on SSB for 20 meters and above but perhaps that is not your objective. Good work!

 

WA8TOD

Re: K5BCQ uBITX Relay Switched LPF/BPF board

MadRadioModder
 

Let’s do it…

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Kees T
Sent: Monday, September 3, 2018 3:26 PM
To: BITX20@groups.io
Subject: Re: [BITX20] K5BCQ uBITX Relay Switched LPF/BPF board

 

The QRP Labs LPF filters are rated at 10W according to Hans Summers, the BPF filters he sells are not, probably because of the series current the capacitors have to handle or larger inductors required. No reason you can't make up BPFs which CAN handle 10W. The filters you see in the pictures are blank boards I made up and you add what components you need to add, and design your own. Could come out with a different BPF filter layout if needed. With those little 1.5" x 0.5" boards you can get 16 per 100mm x 100mm panel .....that's 160 boards per 10 prototype panel order for only $2 plus $5? for scoring plus shipping.

73 Kees K5BCQ  


Virus-free. www.avg.com

--

…_. _._

Re: uBitx Unfiltered

ajparent1/KB1GMX <kb1gmx@...>
 

On Mon, Sep 3, 2018 at 07:25 AM, Michael Babineau wrote:
This got me thinking that for another $20 I could just order the QRP Labs 5W PA kit and build a separate 160m to 10m CW TX with raised cosine wave shaping.
I do mostly CW anyway so giving up SSB wouldn't be a big loss for me.
Why use linear amp with lower efficiency for CW?  Class C can be shaped for keying and offer much mroe power with far less consumed.  However binding the two ubitx to a QSX amp is not easy.

>>Has anyone else thought  of just designing  a separate  TX board  for use with the V3/V4 ubitx? I know that this sounds like giving up ... but in many ways this could be a simpler solution than attempting major surgery on the existing ubitx.

Basically to do that you need to build a replacement fo the rear half of the board.  The problem is fourfold.
No input filtering for the amplifier,
The amplifiers inability to product power at 10M
low pass filter layout (filters would work otherwise)
Board layout.

Allison
We want a magik pill to fix is all.

Re: K5BCQ uBITX Relay Switched LPF/BPF board

Guy WB7SZI
 

Forgive me if this is way over simplified. I’m not an RF designer, 
but couldn’t you manually just insert an appropriate LPF from your ant. connection to the antenna to reduce harmonics on that specific band? I agree that a six band LPF system would be great but I for one only use one or two bands most of the time. Is that doable? 
73,
Guy WB7SZI 

Re: K5BCQ uBITX Relay Switched LPF/BPF board

ajparent1/KB1GMX <kb1gmx@...>
 

Kees,

Before you remount K3 remove the audio switching path from it.  Many get 
feedback from that path.  Also it can be inserted form the bottom.

Also the big issue is all the spaghetti traces. The LPF are good as is, just
the switching is a fail and its all layout.  Too many intereleaved lines.  The real
trouble maker is that all RF in to the filter and out from the filter go by was
of KT1.

In the drawing 3.jpeg The red is new wires yellow are bad wires.
This was built with relays on bottom and works well for 80 through 17m.
KT3 switches antenna to filter outptu or through coax direct to KT1 pin12.
Coax is under board.

In drawing 1jpg  The enclosed in red are the troublesome areas.
Yellow bad, green is audio mod, black means cut!, blue is the spaghetti to be removed/altered

That parallel DC lead (tx relay power) is parallel to RF line from KT3... If it looks like a
directional coupler it works like one. Its why there is a ton of RF on the switched 
DC+ line during TX.  Very bad!

If you don't care for above 17M the fix is messy but easy once the
relays are out.  Use one relay per band from 80/40/20 and it works.
RF goes in via KT1 and out via KT3.  Also modify the relays power
path to avoid that parallel line.  

Allison

Re: uBitx Unfiltered

iz oos
 

Regarding ' Has anyone else thought of just designing a separate TX board for use with the V3/V4 ubitx?' I agree completely considering that many have a separate receiver already.


Il 03/set/2018 16:26, "Michael Babineau" <mbabineau.ve3wmb@...> ha scritto:
W.r.t the current discussions on ubitx transmitter woes ... the route forward that I chose was to order LPFs plus the relay board from QRP Labs. My thoughts were to use a 2nd Arduino Nano clone configured as an I2C slave to allow the Raduino to communicate with the LPF board over I2C. This would require some very minor code changes to send band change info to the new filter board.

This solution would give me clean CW TX from 160m through 10m but does nothing to address the spur problem on the higher bands when using SSB nor the more recent concerns about other IMD. 

This got me thinking that for another $20 I could just order the QRP Labs 5W PA kit and build a separate 160m to 10m CW TX with raised cosine wave shaping.
I do mostly CW anyway so giving up SSB wouldn't be a big loss for me.

So now I am considering the option of just using my ubitx as an HF receiver. The RX works quite well so if I just forget the TX, at a little over $100 for my v3 ubitx is was still a great deal IMHO. 

Has anyone else thought  of just designing  a separate  TX board  for use with the V3/V4 ubitx? I know that this sounds like giving up ... but in many ways this could be a simpler solution than attempting major surgery on the existing ubitx.

I have yet to package my ubitx in a permanent enclosure so for now I am going to put it aside and wait a month or two to see if there is a better option.

Cheers 
Michael VE3WMB 




Re: 80 Meters Harmonics Fix Proposal

Howard Fidel
 

Warren:
I'm peeling the onion, slowly. I thought the problematic band was 15 Meters for SSB?

Gordon:
I don't understand what you are asking me. I provided the simulation file for the 80 meter filter. I haven't touched the other bands yet, I was hoping someone would also try the mod and confirm 80 meter CW is now OK.

Howard


On 9/3/2018 5:05 PM, Warren Allgyer wrote:

Got it Howard. And I agree with both the strategy and the necessary amount of improvement. On mine, a six dB improvement would make all bands legal for CW harmonics. That would be a nice solution for a CW only radio. Of course you must not use it on SSB for 20 meters and above but perhaps that is not your objective. Good work!

 

WA8TOD


Re: K5BCQ uBITX Relay Switched LPF/BPF board

ajparent1/KB1GMX <kb1gmx@...>
 

Now if one does all that and really wants 20 and up spurs and all....

Simple add an inline (between radio and antenna jack) 28mhz low pass filter.
and leave it there.  If it well made it will be invisible (low loss) and at worst
it catches harmonics like the old school TVI filter.  It does not fix the spur
Issue.

So the deal for the relays then is:
           
KT1 selects 20m filter via TXA
KT2 selects 40m filter via TXB
KT3 selects 80m filter Via TXC
none selected is straight through
and the external always inline 28mhz LPF is doing the work.

 **
 * Select the tx harmonic filters
*/  
void setTXFilters(unsigned long freq){
  
  if (freq >= 20000000L){ 
    digitalWrite(TX_LPF_A, 0);
    digitalWrite(TX_LPF_B, 0);  // 10m straight through
    digitalWrite(TX_LPF_C, 0);
  }
  else if (freq >= 14000000L){ 
    digitalWrite(TX_LPF_A, 1);
    digitalWrite(TX_LPF_B, 0);  // 20M
    digitalWrite(TX_LPF_C, 0);
  }
  else if (freq >= 7000000L){  
    digitalWrite(TX_LPF_A, 0);
    digitalWrite(TX_LPF_B, 1);  // 40m
    digitalWrite(TX_LPF_C, 0);    
  }
  else {
    digitalWrite(TX_LPF_A, 0);
    digitalWrite(TX_LPF_B, 0);  // 80m
    digitalWrite(TX_LPF_C, 1);    
  }
}

Re: 80 Meters Harmonics Fix Proposal

ajparent1/KB1GMX <kb1gmx@...>
 

 peeling the onion, slowly. I thought the problematic band was 15 Meters for SSB? 

No its basically 20mhz and up as in all 15/12/10 for SSB.

Allison

Re: UBITX TX level diagramme

Lawrence Galea
 

Thanks Allison
Regards

On Mon, Sep 3, 2018 at 7:41 PM ajparent1/KB1GMX <kb1gmx@...> wrote:
Lawrence G.,

I tried a few things along that path.  made matters worse and that was also tried with
external level 7 mixer and level 17 external mixers.   It was then a rock fell on me
and I realized the output of the 45mhz amp with the TX producing power was filthy.
Add a filter module it got better but by then I had so many outboard modules
its was almost a breadboard radio.  Everything is talking to everything by sneak
paths.  

Allison
We need only one magik part.

uBITX40 filtered

Lev
 

Dear all,


I'm thinking about the adding low pass filters to the output of all
oscillators. The goal is to filter the square wave of the clock generator. I came up with this mixer solution. Using a JFET mixer is just my other experiment.

Question is if this circuit would clean the output signal?

Also, I'm thinking about modifying the IF amplifiers to be tuned.

Any ideas?



73s de HA5OGL

--
Levente Kovacs
Senior Electronic Engineer

W: http://levente.logonex.eu

Re: UBITX TX level diagramme

Glenn
 

Allison, is this the drawing (pdf) referred to?   Attached .BMP copy could be amended with MS Paint.



glenn

Re: K5BCQ uBITX Relay Switched LPF/BPF board

Kees T
 

Close.......

What I am doing on the 4x board (the one compatible with the existing uBITX) design point is:
#1) it fits in the space I cleared on the uBITX board picture,
#2) it selects 3 of the relay sets with the TxA, TXB, and TxC uBITX drivers for 80/60m, 40/30m, 20/17/(15)m,
#3) if any one of those 3 drivers is picked it selects the TXD driver (on the 4x board) which is driven by a 3 input diode dot-OR from the TXA,TXB, TXC inputs. The TxD driver has the 4th 10/12m filter on  the NC contacts so you don't have to have 1 LPF relay energized at all times and may not require K3 if it's the highest band LPF, like on the present uBITX. .....haven't decided yet). 
#4 yes, disabling audio M1/M2 with the same RF relay is strange.

73 Kees K5BCQ

Grounding shematic for a Metal Chassis, which is the right way to wire up?

sdr freak
 

Hello again HAM's !

I have an really important question for all HAM's here, who have their Ubitx in a metal housing or have the knowledge about the grounding options for this way i looking for..

It's like..I want to have my Ubitx in an aluminium chassis and ground everything to this like i see in athread here in forum(i hope its ok to post the pics here), perfect showing what i mean and what i search to understand this correct wire up, look here please:

https://groups.io/g/BITX20/attachment/44890/2/IMG_4811.JPG

https://groups.io/g/BITX20/attachment/44890/3/IMG_4812.JPG

https://groups.io/g/BITX20/attachment/44890/8/IMG_4817.JPG


this is my problem, and i see enough metal cased ubitx's but only few pics with this grounding.. and this is what i look for but i don't understand this whit the logic of the wire up v1.9 in this forum, look here:

https://groups.io/g/BITX20/photo/49276/0

also i want ask for a picture to wiring the grounding when use a metal chassis, because i doesn't unterstand the wire up shematic(v1.7;v1.8,v1.9) here in forum. because in all this wire up shematic, i read that it's the best to use metal chassis and but be careful of 'ground loops' and then the 'sleeves are grounded'...
so that is really dificult for me to understand this shematic what does it mean whit Ground Loops and so on..

and now i don't know what is the 'wire up shematic for metal chassis' and which cable should have to stay at the place when i wish to build a nice grounded ubitx, like a chassis which is grounded + have a grounding-screw at the backside plate to ground the whole ubitx at the main ground in my home, for any secure and on the other side a have a nice grounded chassis where all the things have their ground like 'mic/ptt-jack , keyer-jack , audio-jack, ,the encoder-button, the turning resistor for nf voulume,  possibly additional switches, antenna conection,..

ok i think you can be understand what i mean, i look for all things in the ubitx they are have ground connect, few things directly  to the raduino or the main board, and the raduino and the board + display are also this things which i doesn't understand to ground this when use metal chassis and i look for my idea to make all grounding to a main chassis-ground-screw..

Can anybody help me there, so that i don't make mistakes who destroy anthing in the ubitx..? Is there possibly anyone who have a ubitx in metall case and can say what he does in this obstacle. please don't laughing at me ...
(i'm really read for weeks and its not like a have not search for, but i'm really confused with this 'Grounding Chassis and make it Right' so now i must hope for all help of anybody who is know i feel whit this problem like ''why i'm don't understand..why? is it like,..humm..sh*t why does i find no way in this alone..'' .. it's like a war in me and feels like there is no way to get smarter.. but i would love to get this smartness, to understand this things mostly complete at my self alone.. but sometimes it shouldn't be..)

ok i don't make it any larger - i hope for help thanks!!

Best regards Fabian !

Re: 80 Meters Harmonics Fix Proposal

Howard Fidel
 

Yes, I stand corrected, but Warren said 20 meters, not 20 MHz.

On 9/3/2018 5:35 PM, ajparent1/KB1GMX wrote:
 peeling the onion, slowly. I thought the problematic band was 15 Meters for SSB? 

No its basically 20mhz and up as in all 15/12/10 for SSB.

Allison


Stone Soup

Warren Allgyer <allgyer@...>
 

Folks

I refer you to a famous story. It comes in many variations and this is just one: http://www.dltk-teach.com/fables/stonesoup/mtale.htm

I am the last person to discourage experimentation.... it is what I do, both for a living and for fun. But this is getting ridiculous.

We have here a platform that literally does nothing well. Nothing. Its only claims to fame are 1) It is inexpensive and 2) it is software configurable. The uBitx is a horrible transmitter, perhaps a worse receiver, bereft of simple operating niceties like AGC, ALC, preselection filtering, etc. As it comes out of the box it is illegal for air operations in most countries in the world. Its receiver has no front end, no filtering, miserly overall gain, and lousy audio. The transmitter cannot be put on the air legally and maintained without thousands of dollars of lab grade test equipment. Even as a core SSB generator it is 1960's technology executed badly.

And all of that would not be so bad if it were not for the fact that it IS put on the air, in the vast majority of cases, without the necessary lab equipment and testing simply because it does a lot of bands very inexpensively. This is the Twinkie offered to a starving child, the shipping container begging to become a multimillion dollar condominium,  the tricycle with dreams of winning the Indy 500. All possible..... but all ultimately futile for all but a persistent, doggedly stubborn few. And the others who try will simply add to the noise and junk that has become HF around the world.

Even the narrative that this represents employment for needy women in a third world country.... even that does not justify foisting this on amateur radio operators around the world. Producing garbage does not lift a segment out of poverty..... it just makes more garbage. It is very, very disappointing to see the hobby I have loved for 50 years be reduced to this.

If there was ever an electronic analogue for "Stone Soup", it is uBitx.

WA8TOD

Re: 80 Meters Harmonics Fix Proposal

jim
 


On Monday, September 3, 2018, 11:51:11 AM PDT, Warren Allgyer <allgyer@...> wrote:


Howard

When I measured 80 meter harmonics the particularly troublesome ones were 5th at 18 MHz and 7th at 25 MHz. In both cases the attenuation of the stock uBitx at those frequencies was limited by the layout of the board and by the coupling of relays sharing both filter input and output in the same frame. In such cases the characteristics of the filters, both existing and any modifications are immaterial. The attenuation of the stock filter supplied is more than adequate. But the harmonics bypass the filter and go via I/O coupling straight to the output. Please measure the 5th and 7th harmonics on CW. I think you will find you have not done much to improve the stock situation.

WA8TOD

Just a fyi ...see the picture of the 80 meter output from my unit ...after doing the L7,L8 mod and the output transformer mod .
A whole bunch of the cruft flying around in this radio is due to L7 and L8 having DC current flowing through them ...This DC biases the ferrite (shifting the BH curve who knows where) lowering the inductance and allowing RF everywhere ..

Put a proper inductor on the IRF510's that is NOT affected by DC current flowing through it and see what you get

Jim
_._,_._,_


Re: Stone Soup

Jerry Gaffke
 

Warren,

The uBitx is just fine as a QRP 80/40/20 SSB transceiver once the LPF's are cleaned up. 
Or as a good general coverage receiver.
Or as a testbed to learn about radios and arduino programming.
Good luck finding anything better for the price.

Perhaps you should find yourself some other forum to haunt.

Jerry, KE7ER



On Mon, Sep 3, 2018 at 05:37 PM, Warren Allgyer wrote:

Folks

I refer you to a famous story. It comes in many variations and this is just one: http://www.dltk-teach.com/fables/stonesoup/mtale.htm

I am the last person to discourage experimentation.... it is what I do, both for a living and for fun. But this is getting ridiculous.

We have here a platform that literally does nothing well. Nothing. Its only claims to fame are 1) It is inexpensive and 2) it is software configurable. The uBitx is a horrible transmitter, perhaps a worse receiver, bereft of simple operating niceties like AGC, ALC, preselection filtering, etc. As it comes out of the box it is illegal for air operations in most countries in the world. Its receiver has no front end, no filtering, miserly overall gain, and lousy audio. The transmitter cannot be put on the air legally and maintained without thousands of dollars of lab grade test equipment. Even as a core SSB generator it is 1960's technology executed badly.

And all of that would not be so bad if it were not for the fact that it IS put on the air, in the vast majority of cases, without the necessary lab equipment and testing simply because it does a lot of bands very inexpensively. This is the Twinkie offered to a starving child, the shipping container begging to become a multimillion dollar condominium,  the tricycle with dreams of winning the Indy 500. All possible..... but all ultimately futile for all but a persistent, doggedly stubborn few. And the others who try will simply add to the noise and junk that has become HF around the world.

Even the narrative that this represents employment for needy women in a third world country.... even that does not justify foisting this on amateur radio operators around the world. Producing garbage does not lift a segment out of poverty..... it just makes more garbage. It is very, very disappointing to see the hobby I have loved for 50 years be reduced to this.

If there was ever an electronic analogue for "Stone Soup", it is uBitx.

WA8TOD