Date   
Re: VK4PP uBitx LPF BANK add-on Board

MadRadioModder
 

No sooner did I say that some folks will be challenged to correct the spur issues with surgery and internal boards… and low and behold !… KE4MIQ posts a very simple outboard filter board… exactly what I was talking about.  It’s not for everyone but it’s gonna work for some!

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Timothy Fidler
Sent: Sunday, September 2, 2018 6:43 PM
To: BITX20@groups.io
Subject: Re: [BITX20] VK4PP uBitx LPF BANK add-on Board

 

MRModder it is not so much a a mess. If they realise they cannot safely add an amp and they spin the dice as far as a letter from the FCC/SMA then the sun rises each morning much the same.  The issues for them will be overtaxed components,  vias not fully plated through and needing a soldered in copper stub  and such like.  I guess they did nto figure on getting component removal and SMD soldering skills when they signed up. Bit like the Army or Marines. have to Man up  and tool up   :-))  Perhaps  A F could put something like that in his advertising Spiel .. So saith Don Draper... Perhaps not.

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

 


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

 

To:

<BITX20@groups.io>

Cc:

 

Sent:

Sun, 2 Sep 2018 08:07:13 -0500

Subject:

Re: [BITX20] VK4PP uBitx LPF BANK add-on Board

I suppose that does depend on a person’s skill at executing the myriad of expert opinions opined on this group.  I myself do this for a living so I’ve redesigned the entire radio.  That’s one end of the spectrum.  However there is the other end of the spectrum… the guy who may have just received his license and bought a uBITx thinking it was a nice cheap way to enter the world of HF that now has to deal with this (like some friends of mine).  They can either rely on the experts (self-proclaimed or otherwise) to bail them out of this mess or be given a very simple solution that is possible for them to execute.  “Hellish crude” in your own words for you… the only option for someone else.

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Timothy Fidler
Sent: Sunday, September 2, 2018 1:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] VK4PP uBitx LPF BANK add-on Board

 

All understood but it hellish crude for a radio which allegedly has push button RF operation selection.

 

Well it had it ....

 

Just too many design compromises made. If they had gone for 80 40/30 20 and Ten  mtrs   with four filters and a diode OR ..(given the limits ofthe Arduino ) all standard stuff ...the whole thing would never have happened. 

 

so it goes.

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

 


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

 

To:

<BITX20@groups.io>

Cc:

 

Sent:

Sun, 2 Sep 2018 01:06:02 -0500

Subject:

Re: [BITX20] VK4PP uBitx LPF BANK add-on Board

I just soldered female BCN connectors to the 4-pin DuPont connectors and plugged the DuPont connectors onto the filter(s)  I then use a double barrel male to connect the filter to the back of the radio.  It’s very simple.  I’m not currently at home or I could post a picture but I think you get the idea.  I suppose you could put this onto a small proto-board easily…or even use Kees board if you wanted to do something more official  This approach takes this whole spur removal well within the capabilities of even the person that barely knows which end of the soldering iron to hold.

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of mark bodlovich
Sent: Saturday, September 1, 2018 11:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] VK4PP uBitx LPF BANK add-on Board

 

Mad Radio Modder;
I'm interested in how you put the qrp labs filter board into the ubitx. I built one and have not put it in yet. Looking for good ideas. 
Thanks, Mark N7HWR

 

Virus-free. www.avg.com

 

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Sustained Transmit Power #firmware

Larry Plummer
 

I have ordered but not yet received a uBitX which I plan to use for 40 meters WSPR.  I have two questions:

1.  Is the simple crystal for the Si5351 sufficiently stable (at least after warm up) for digital modes?  I build WSPR transmitters using the Si5351a for timing but use a Fox TCXO module which costs less than $2.50 instead of a crystal.

2.  WSPR has long 1 minute 52 second key down transmit times.  I plan to transmit on alternate cycles, i.e 2 minutes transmit and 2 minutes recieve.  Will the uBitX support sustained output of 5 watts sith this duty cycle?

Larry
W6LVP

Re: VK4PP uBitx LPF BANK add-on Board

Gordon Gibby
 

Nice setup !!
Gordon



On Sep 2, 2018, at 21:09, Kees T <windy10605@...> wrote:

Here is what all 4 uBITX LPFs look like as plug-ins. Note that the 6x LPF board is arranged to where you can cut off 1 or 2 of the LPF/BPF positions with no ill effect.

73 Kees K5BCQ<MVC_011S.JPG>

CW OPERATION

W2CTX
 

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: uBitx Unfiltered

Jim Tibbits
 

So trying this from another path.   Did some poking and looking at the Q90-Q97 path today ..Noticed that Q911 thru Q98 all have 100 ohms from the base of the transistor to ground (biasing network) The problem is you only end up with 1 volt on the base ..And with a threshold of 0.7 volts Vbe, that doesn't give much room for any work to be done ...changed them all to 220 ohm ...some better...
pa to filters transformer mounted.jpg
10 meters - 1.8 watts.jpg
20 meters - 10.24 watts.jpg
40 meters - 10.88 watts.jpg
80 meters - 9.52 watts.jpg
L8-L9 substitute mounted.jpg
Photos show the gain now ..I will change them out to 330 ohm tomorrow and re-align the bias settings for maximum flatness again . Test 80,40,20 and 10 on the SA ...Photos also show the mod I made to replace L8 and L9 ...Those units have DC current flowing through them and that messes with the inductance ..Schematic shows them as 60 uH ..I measured mine when I removed them ..24 uH..Checked inductance while flowing DC current through them and at 10 mA inductance decreased to 14 uH....As those flow minimum 100 mA, I doubt there was much inductance left ...As these are supposed to keep all the nasty RF out of the power supply. I think its little wonder all the spurs created ...The band test I ran showed 9.5 watts on 80,... 10.8 watts on 40,... 10.24 watts on 20 and only 1.8 watts on 10 .. Likely the stacked core "binocular" is contributing th that as it isn't one lump of ferrite ..Losses between the pieces ...


On Sun, Sep 2, 2018 at 10:16 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
On Sat, Sep 1, 2018 at 08:49 PM, jim wrote:

consider ..Ft of 2n3904 is about 250 Mhz ...If beta rolls off at 6db/octave, then =at 250 Mhz, beta = 1..125 Mhz beta 6db better  (3db doubles =beta 2, 3db doubles beta 4)..60 Mhz 12 db better (4 doubles  2,4,8,16)...30 Mhz 18 db better .(6 doubles 2,4,8,16,32,64)..
I finally found your text. You are writing inside the quoted section and the web version only shows a blue rectangle with three dots...  on an other wise blank page.  Be careful of the Emailer as its likely burying your answer as a the other guys quote.

Your supposition is however wrong.  For common emitter resistive feedback that is untrue.  The gain falloff is 6db octave
starting at some low frequency so by time you at 30mhz you have gone through a few octaves (3+ for 3-30 or -20db)
you are well down. Add feedback and you are way down as it does not decrease with frequency (in the ubitx case).
It is possible to have a feedback that decreases with frequency but you still run out down the gain.  Where does the
bend in the curve start?  Usually less that 3mhz and its downhill from there.  Also with wideband amsp the C-B feed
back capacitance and other parameters are not in that and they tend to be input and output impedance sensitive
as well as operating current influenced.

The usual calc for resisitive feedback the first parameter is FT/F=  for 3904 its about 300mhz/30 or a beta of 10.  With
that try to make a power amp stages of 18db, voltage gain maybe but not power.  Assume 50 ohm input and output,
but it doesn't happen even with 200 ohm output.  

That and the HFE as I've written many times before falls with increasing current over 10mA, its in the datasheet.  When
you combine that performance at even milliwatt power is a fail.  At 20Ma is on the down side and at 50mA its down
from the peak by 40%. That or unbounded optimism or a hot batch.  With no margin and a lot of luck how many out
of a thousand will perform well.

Reality is that the 3904s in enough units to be a valid confirm are not performing.  Dial in RF1 for 11W at 80M
the driver output is easily a half watt.  By 30mhz you are down 11db to maybe 45mw.  Where'd the gain go?

Same for the 45mhz amp.  In isolation at 10mhz its 18.9 db, at 45mhz its 13db for 50 ohm in and out as that is
what the filter matching network expects and the mixers.  Also around 15mhz the IF amp is showing noticeable
and increasing phase shift when that hits a high enough number instability is seen save for the projected path
is not enough gain at that point..  Now we add the darlington pair effects sine they are running at .99999 (alpha)
their voltage gain is essentailly one but power gain is the result of high input impedance (limited to the prior stage)
and output impedance or about 4 (6db) so the IF amp has an apparent gain even with the poor showing of the 
3904 of some gain just due to the output power gain of the compounded emitter follower.

Yes you can get 3904 to oscillate at 450mhz too.  Doesn't mean anything as not all do.  But then I got a uV201
to oscillate at UHF once.
 
Allison

Re: CW OPERATION

Jim Sheldon
 

The explanation is absolutely correct.  

To all programmers of CW for the uBITX.  You do NOT offset the transmitter by the sidetone frequency!  When you press the key, the uBITX must transmit exactly on the display frequency and the RECEIVER must be offset from that frequency by the value of the sidetone.  Watch the video that W2CTX posted the link to and it explains how it should work.

Jim Sheldon, W0EB
CW operator for over 50 years.

On Sep 2, 2018, at 9:01 PM, W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: CW OPERATION

Jim Tibbits
 

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: CW OPERATION

Gordon Gibby
 

Yeah but the point is it’s the receiver that should offset. Not the transmitter


On Sep 2, 2018, at 22:31, Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: CW OPERATION

Gordon Gibby
 

You can do it the other way around, with the transmitter upset, but then you have to be absolutely certain that the user knows that their transmissions are offset from the dial number.

That’s not terrible, that’s exactly what happens when you’re doing upper or lower sideband, and certainly when you’re doing pseudo CW by injecting an pure audio sinewave signal into a single side band system.  FLDIGI will do that, and you can even rig it so your computer shows your correct transmitting frequency


On Sep 2, 2018, at 22:31, Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: CW OPERATION

Jim Tibbits
 

absolutely

Jim

On Sun, Sep 2, 2018 at 7:33 PM Gordon Gibby <ggibby@...> wrote:
Yeah but the point is it’s the receiver that should offset. Not the transmitter


On Sep 2, 2018, at 22:31, Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: CW OPERATION

W2CTX
 

Did you watch the video?


rOn

On September 3, 2018 at 6:36 AM Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX < w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

 

 

Re: CW OPERATION

Jim Sheldon
 

Yes and it was reasonably well done but oversimplified a bit.

On Sep 2, 2018, at 9:36 PM, W2CTX <w2ctx@...> wrote:

Did you watch the video?


rOn

On September 3, 2018 at 6:36 AM Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX < w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

 

 

Re: VK4PP uBitx LPF BANK add-on Board

W0PWE
 

Kees - With 6 filters is the plan as follows?
LPF1 = 80M
LPF2 = 40M and 30M
LPF3 = 20M and 17M
LPF4 = 15M
LPF5 = 12M
LPF6 = 10M

Re: CW OPERATION

Jim Sheldon
 

I don't like to be overly critical, but I've been hinting for months now.  I am now openly stating that KD8CEC's software has it wrong and it's been wrong from the beginning.  I call on Ian Lee to clean up his code and get it right before he adds any more junk to his programs.

Jim, W0EB

On Sep 2, 2018, at 9:33 PM, Gordon Gibby <ggibby@...> wrote:

Yeah but the point is it’s the receiver that should offset. Not the transmitter


On Sep 2, 2018, at 22:31, Jim Tibbits <ab7vf1@...> wrote:

Gotta offset,  can't hear em on the carrier

On Sun, Sep 2, 2018 at 7:01 PM W2CTX <w2ctx@...> wrote:

Found this video explaining CW Zero-beating.  So based on this explanation the following is illustrated

for 7.040.000:    Dial displays 07.040.000, you transmit on 07.040.000, and the receive is offset by the

sidetone value.


Of course this is based on the video being correct.


https://www.youtube.com/watch?v=CrC7JmNw1eY


rOb

Re: Perspex Case

kevintg51@...
 

Wow that looks sooooo good. Great work
Cheers
Kevin VK2KTG

Re: VK4PP uBitx LPF BANK add-on Board

Nick VK4PP
 

Ok, just adding a bit in here from my side:
Relay 1-3 are triggered using the existing 3904s onboard.
Relay 4 is a drived via a new 3904 and an extra digital I/O.
Firmware changes will be needed regardless as its one output on at a time per filter.

Added 100uh smd inductors for RF filtering.
If you all like it so far. I will make 10, and happy to post to a few of you with test equipment at no cost, please contact me if you want one.




73 Nick VK4PP

Re: CW OPERATION

Jerry Gaffke
 

Ian's software is the most popular update available for the uBitx.
He has added a lot of functionality to the rig and that is to be applauded.
It's taken months of free time for him to bring it to this level.
Could well be that Ian doesn't use CW much, and CW is not a priority for him.

Getting an iambic keyer to feel right is best done by a serious CW operator.
I'd think Jim Sheldon would be an excellent candidate.

Jerry, KE7ER


On Sun, Sep 2, 2018 at 08:00 PM, Jim Sheldon wrote:
I don't like to be overly critical, but I've been hinting for months now.  I am now openly stating that KD8CEC's software has it wrong and it's been wrong from the beginning.  I call on Ian Lee to clean up his code and get it right before he adds any more junk to his programs.
 
Jim, W0EB

Re: VK4PP uBitx LPF BANK add-on Board

Nick VK4PP
 

The ideas is to use exiting LPFs as is, with the option to add a fifth if you so chose, 160m... or better 10m....

But mainly better lay out and separate relays...
I will provide a code snip-it for replacing the section in the original/KD8CEC FW for use with this board.

Kees, I am happy to combine efforts/butt out if you feel having 2 board options will confuse things, please contact me if you want to chat about this off-line...

73 Nick VK4PP

Re: CW OPERATION

Tom, wb6b
 

This issue come up over and over. The factory software has (or at least originally had) the same issue. A comprise would be for the display to switch to the TX frequency when you key the transmitter with the CW key. At least people would get some feedback to know that is happening. I think Ian responded in a previous thread on this issue with a setting in his uBITX memory manager that would at least do the display the frequency on transmit. It may be in the CEC documentation, but I don't remember what it was.

If you try to set your receive CW tone to the same as the sidetone when you send CW, that will get you close. Better would be for the functionality to be included for everything to work how the video explains it. Adding a true zero beat function might involve a hardware change, or injecting the sidetone audio at a lower volume, during receive, with an added  button.

Tom, wb6b

Re: Sustained Transmit Power #firmware

Tom, wb6b
 

I ran a WSPR beacon with my uBITX for several weeks. I found that it was rare for the TX frequency to drift during a transmit cycle. And only a HZ if it did.

I ran a fan on the heatsinks and the heatsink temperature was warm but not hot.  I ran a 20% TX/RX duty cycle. But 50/50 may not be much different. 

It was tricky to get the PPM adjustment right in the WSJT-X WSPR software. The big source of confusion was I could not get the PPM adjustment to converge on the desired frequency. That turned out to be, when using the CAT interface from WSJT-X to the uBITX, the uBITX would only step in the same step size as programmed for tuning with the frequency dial. Setting the frequency step to the minimum step size fixed that issue.

Tom, wb6b