Date   
Re: My wish list for ver. 6 of ubitx

Curt
 

Iz

If I were Farhan - I would move on to other things!  Let's see what's in the future -

Given that we have thousands of v3, v4 and v5 around the globe -- I suggest that some merchant(s) kit 'the essentials.'  Its not like me not to comment (and think some) - here goes --

1) separate relays were used at the input and the output of the LPF, to be fully sure I exploit the filters at their potential;  -- I like the idea of separate relays.  I am blessed to be using such a board designed by a gracious list member -- now we just need someone to kit it for sale -- it works very well. 

2) add the possibility to add an RX preselector in the chain;  maybe my antennas are too small because I really don't need it.  okay I don't plan to use the rig in CQWW -- its fine 99% or more of the time. 

3) AGC.  I really like the simple VK3YE AGC - its working wonderful and requires NO changes in the board.  2 transistors - build it your favorite homebrew style - okay 2 key things to source - a LDR (aka photoresistor) and a bright LED.  the former from junkbox, the latter from some device that broke.  (I will confess I am still having trouble getting the ND6T to do anything in my rig -- trying to use it to feed S-meter.  it seems to work for everyone else - stay tuned to see what I may be missing)


4) RV1 externally adjustable - my no change to board here - just move it to the front or back panel.  now - do you or I have the wisdom to use it without a spectrum analyzer?  I am doubting it in my case! 

5) op-amp output for SDR receiver/panadapter.  me I would have said a SCAF audio filter.  but again, this is easy to add.  someone who never does CW might not need it at all, but I do use it some on SSB.  one could mount a simple board on its connector to host this.  Sunil may be taking notes! 

6) switchable RF finals and separate very low power output to drive V- U external transverters without the need of attenuators.   sure I thought about this!  well if a V6 would obsolete our rigs (I don't see this coming anytime soon!) -- we just need to cut away the PA's and build our own V/U machine.  perhaps when Farhan & friends launch their second satellite the V/U uBITX will land on planet earth. 

PS - I think we still lack much data on how much as been solved by v5.  honestly I think I prefer the narrower filter in v4 for SSB.  I can recount that trying some v5 changes in my v4 did not help much.  at the moment I am viewing my v4 as 'the glass more than half full' -- I am clean on all CW bands, and on SSB all the way up to including 17m. 

the uBITX remains a rig for the whole planet - the adventure does continue. 

73 Curt

CW key sticking with Nextion LCD

Joe Puma
 

I recently installed the 5” Nextion on uBitx Rig. I noticed that on the 10 meter band the CW key sticks when pressed and there is a noisy tone that goes along worn it. I guess this is RF getting in the line. If I disconnect LCD from power it goes away. I’ve been trying out .1 uf caps on things I seem to be having RAF issues with and it’s been fixing it with great success. So for the keyer I put a cap over the blue wire going to LCD and ground. It stopped the sticky CW key and I don’t hear the squealing RF in the signal.

Now on 18mhz when I key the CW keyer I hear some hiss when I unkey during that delay time which is 600ms. I also see other weird things that happens during that 600ms delay. When RF was getting in even though it didn’t make the key stick during that delay time, my power and swr goes up briefly. I can make the delay be 0 and be done with it. I only use the CW keyer to trigger my auto tuner so I don’t need the delay but that odd surge in power and swr makes my auto tuner retune after I let go of the CW keyer. It makes using it a tuner tigger useless.

Normally during that delay you dont see any signal but if there is RF in the chain it seems to discharge it back out onto the antenna port during that delay process. This causes the auto tuner to tune.

I’ve only noticed it with the 5” LCD installed.

Jow
KD2NFC

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

 

John,

Try a higher value for R104 like 100K preset or pot. The current the diodes need to conduct is very small IMHO.

Raj

At 09/04/2019, you wrote:
Thank you for the reply Dexter.

The strange thing is that the control voltage at the mixer swings from a virtually zero value (0.2mV DC on key up) and a full conduction value at 245mV DC on key down.

The 245mV value did not change significantly when I reduced the R105/R104 values so it seems to indicate that the mixer diodes are fully conducting on Key down as expected.

Also something I didn't mentioned before: when I disconnect the wire between T4(3,5), that is the clock #1 mixer, and R105 I get no unbalancing of the mixer and a very weak transmitted signal as expected on key-up (or key-down for that matter as it is disconnected).

So it is as if the clock #1 mixer would be much more sensitive to unbalancing than the clock #2 mixer.

Scratching my head on this one.

73, John

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

Ted
 

John,

RE:  "The 245mV value did not change significantly when I reduced the R105/R104 values....."

If you're looking for a power change via R104, you must increase that resistance value (from the stock 2.2k up to to 3k, 5k, 8k, etc) in order to decrease CW power output.  I've shorted R104 outright, and power remains at its full potential. Only by increasing value does anything move away from stock output there.

Just making sure that you're getting to where you meant to be on this.



Best regards,

Ted
K3RTA

Re: My wish list for ver. 6 of ubitx

Dennis Zabawa
 

Ver. 5 cleverly upgraded previous versions tackling most of the  issues. In any case I would move for a ver. 6 if:
1) separate relays were used at the input and the output of the LPF, to be fully sure I exploit the filters at their potential;
**** Definitely *****
2) add the possibility to add an RX preselector in the chain;
***** No *****
3) AGC
***** Definitely *****
4) RV1 externally adjustable
***** No *****
5) op-amp output for SDR receiver/panadapter
***** No *****
6) switchable RF finals and separate very low power output to drive V- U external transverters without the need of attenuators. 
***** NO *****
Of course I would not pretend to stay in the same price range.

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

John (vk2eta)
 

Thank you for the reply Dexter.

The strange thing is that the control voltage at the mixer swings from a virtually zero value (0.2mV DC on key up) and a full conduction value at 245mV DC on key down.

The 245mV value did not change significantly when I reduced the R105/R104 values so it seems to indicate that the mixer diodes are fully conducting on Key down as expected.

Also something I didn't mentioned before: when I disconnect the wire between T4(3,5), that is the clock #1 mixer, and R105 I get no unbalancing of the mixer and a very weak transmitted signal as expected on key-up (or key-down for that matter as it is disconnected).

So it is as if the clock #1 mixer would be much more sensitive to unbalancing than the clock #2 mixer.

Scratching my head on this one.

73, John

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

John (vk2eta)
 

Thank you Ted.

That may well be my final option.

I was hoping for a software controlled power level as I already do in with the SSB signal by using the gentle (relative to an audio passband) slope of the 45Mhz filter to flatten the power output over the 80m-10m range.

But I can live with say 2 watts for tuning at 80M and 1 watt at 10M. Still very usable and low enough to safeguard the finals during tuning.

73, John

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

Dexter N Muir
 

A possibility for the CW just changing amplitude: is the 'unbalancer' driven from an Arduino output? That could be going from low to high - either of which would unbalance. I'm not an Arduino expert, but could that output be configured to be "off=open"? The alternative would be a transistor in there to make it go either (the greater) to open.
73 de ZL2DEX

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

Ted
 

Here - let me suggest an alternative:

1. Cut trace on either side of  R104.
2. Add a 10k trim pot in series with R104.
3. Adjust new trimmer for desired CW carrier output.
4. Enjoy favourite cold beverage.

This works exceedingly well, unless by chance you're looking for a software answer so that "tune" RF is lower than operating RF.  This hardware solution works fine on v.3, 4, or 5.

Ted
K3RTA

Re: Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

John (vk2eta)
 

Sorry for the typo and bad sentence. The first question should read:

1. What can create this reduced difference between the unbalanced and balanced state of the clock #1 mixer?

73, John

Trial to control CW power (and reduce harmonics as a result) by unbalancing the 2nd mixer #ubitx

John (vk2eta)
 

After a week working on this mod I need help as I can't come up with a logical explanation as to what is happening.

 

My uBitx is a V3. It has a few mods and works well, good receive sensitivity, Tx power within range. Previous mods which could be of interest for this question: Allison’s 2N2222A as pre-driver, drivers and BFR106 as Q90, Axicom relays, Raj L5/L7 replacement with designated SMT inductors.

This mod summary: in a stock uBitx, on CW key-down, the mixer fed by clock #2 is unbalanced (the output of the Arduino CW-KEY is set high).

The mod is to move the unbalancing from clock #2 mixer to clock #1 mixer, then adjust the software to generate a 45Mhz(+ or -) on clock #1 and a (45Mhz + Tx target freq) on clock #2.
The TX frequency is generated as a beat between the 45Mhz and the (45Mhz + Tx freq) in the clock #2 mixer. CW power control is done using the slope of the 45Mhz filter to reduce the amplitude of the 45Mhz signal.

Prime personal objective: control CW power level (for my integrated auto-tuner).

Side benefit: Reduce the level of harmonics present in CW mode as we currently feed a square wave directly at the transmitting frequency. With this mod the 45Mhz filter will filter the clock #1 harmonics, and the beat of the harmonics of clock #2 and clock #1 should be well above the L1-L4/C200-C204 filter. This is particularly of value for the 80,40-10M band where the harmonics in CW mode are more of an issue. The drawback is that we may now have spurs in a similar manner as SSB signal, although the first mixer is not used in this case.

 

This is not my idea and was mentioned before by Jerry Gaffke and others (E.g. https://groups.io/g/BITX20/topic/16656657#45805)

 

Details of the mod:

 

1. Disconnect (cut trace) from R105 to the common connection of C10, R27 and T2 (3,5).

2. Connect via a wire the disconnected side of R105 to the common connection of T4 (3,5), C211.

I passed the wire under the board by drilling two small holes next the two connection points to ensure minimal pick-up of RF.

 

3. Change the software to, when in TX CW mode, disable clock #0, generate a clock #1 at “SECOND_OSC_USB” - “usbCarrier” = 45Mhz (+ or -) and clock #2 at (that same 45Mhz signal + target Tx frequency).

 

Results:

 

I get a signal on a control receiver at the expected frequency, so the software logic seems to be ok.

 

But two problems:

 

a) I get like a permanent unbalancing of clock #1 mixer. The difference between key up and key down is only about 3dB.

 

b) It generates a much lower power level: example at 40M it delivers 12W in CW mode in stock configuration, I get 1W with this mod on key-down (and 1/2W on key up). At 10M I only get 100mW and 200mW (Key up/ key down respectively) which is too low for my auto-tune.

 

Further tests:

 

I checked the voltages on the common connection of now R105, T4 (3,5), C211 and I get 0.2mV DC on key-up and 245mV DC on key down which I believe is consistent with the diodes forward bias. This should have the mixer go from a well balanced state to a well unbalanced state.

 

I checked that by moving the 45Mhz clock #1 signal around the peak of the 45Mhz crystal filter I would get a variation in output power and would get a peak where expected and it worked as such. The further from the filter peak, the lower the output CW power.

 

I tried to reduce the values of R104 and R105 by 1/3. This reduced the power on key-up and on key-down by about the same ratio, so not a win either on the unbalance issue.

 

I checked that the first mixer was not left “floating” and that this could create a problem. I added a 1.2Kohms resistor from T2(3,5) to ground. It made no difference when I injected clock #2 at the TX frequency. I would get a very low signal on the control receiver, proving that the mixer of clock #2 is balanced with and without that resistance.

 

Questions:

 

1. what can create this reduce difference between balanced and balanced clock #1 mixer?

 

2. Do we expect that a same level clock #1 signal that the one generated by clock #2, passing through the 45Mhz filter then amplified by Q20,Q21,Q22 stage would be of a lower level than the clock #2 signal coming through the first mixer? As far as I remember the conversion losses of a ring mixer is around 5 to 6 dB. Here we have a difference of around 10dB so something else is at play I suspect.

 

Ideas welcomed.

 

Thanks and best 73, John (VK2ETA)

 

Re: ubitx spurs?

 

I'm afraid it was already set to the half way mark.
Is there something particular I should be looking for?

At this point I'm having enough fun taking measurements and
improving things as I go along.

Thanks,

John
W1JDS


On 4/8/2019 8:46 PM, Ashhar Farhan wrote:
you should setup the RV1 properly. Set it to half-way mark.
- f

On Tue, Apr 9, 2019 at 8:50 AM iz oos <and2oosiz2@...> wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

Re: ubitx spurs?

 

Thanks, I'll look into that.

John
W1JDS

On 4/8/2019 8:20 PM, iz oos wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).



Re: ubitx spurs?

 

I did post some CW data a few weeks back as I swapped out the relays and inductors.
Some of the data is suspect given unexpectedly high power readings.  If you can read an
Excel file I can send the whole thing to you directly.  In general all was good after
the mods except for 80m where the first harmonic after the fundamental as off by 6 dB.
I've only checked 10,20,30,40,80m in CW.

I am using an Agilent 33220A function generator.  I'll see if I can drive it up to similar
power levels Friday night aka "My Time".  I'll try to cover all bands next time.




On 4/8/2019 12:59 PM, Curt via Groups.Io wrote:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

My wish list for ver. 6 of ubitx

iz oos
 

Ver. 5 cleverly upgraded previous versions tackling most of the  issues. In any case I would move for a ver. 6 if:
1) separate relays were used at the input and the output of the LPF, to be fully sure I exploit the filters at their potential;
2) add the possibility to add an RX preselector in the chain;
3) AGC
4) RV1 externally adjustable
5) op-amp output for SDR receiver/panadapter
6) switchable RF finals and separate very low power output to drive V- U external transverters without the need of attenuators.
Of course I would not pretend to stay in the same price range.

Re: uBitx V5 Audio improvement

Jerry Gaffke
 

For LM386 gain that is flat across 300 to 2300 Hz 
and is more than 26dB (no cap) but less than 46dB (10uF cap),
this is done by adding a resistor in series with that 10uF cap.

Re: uBitx V5 Audio improvement

 

Farhan,

For ear buds you should put a 100 ohms or so in series with the speaker output line. That will prevent blowing ears and ear buds!

Raj

At 09/04/2019, you wrote:
LM386 distortion really increases with increased gain. gain is not sensitivity. a better idea might be to bypass pin 7 to ground with the 10 uf.
either way, keep experimenting. I tried an external TDA2030 audio amp connected directly from the volume control. It can blow your ears if you are using earbuds, but it was really cool for speaker listening.

Re: ubitx spurs?

iz oos
 

I meant before the 45mhz mixer. Being the LPF exactly the same and in the same position found in ver5 of the ubitx


Il 09/apr/2019 05:20, "iz oos via Groups.Io" <and2oosiz2=gmail.com@groups.io> ha scritto:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt

Re: Space

Kelly Mabry
 

Indeed, it was my cross circuiting to B....   ...fascinating!

Re: ubitx spurs?

Ashhar Farhan
 

you should setup the RV1 properly. Set it to half-way mark.
- f

On Tue, Apr 9, 2019 at 8:50 AM iz oos <and2oosiz2@...> wrote:

John, you made an excellent job with the relay replacement and the two inductors mod, for the higher bands you might also consider to add the LPF Farhan filter before the 45mhz filter. I have done it with two small (green-white) toroids (12turns to get exactly the required inductance) and a cap. It is rather easy to install (Manhattan style).


Il 08/apr/2019 22:00, "Curt via Groups.Io" <wb8yyy=yahoo.com@groups.io> ha scritto:
John

visibility appreciated.  it should behave like most v4's.  here is what I suggest --

take some CW data.  as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.  in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.  (we all realize we don't have ALC in the stock design).  many of us have issues on the 3 highest bands especially. 

if you have harmonic issues - one cure is using a daughter board with relays to replace  one side of the filters - it is working nicely in each ubitx that has tried this solution.  others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding. 

I am confident the harmonic spurs are very fixable.  I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB. 

yes good idea to have some before deciding on your display and a matching case. 

Curt