Topics

uBitX assembled: bit of a challenge with alignment/bfo adj - Volume/switch knob fix

Dan D'Eon
 

Hello. Got my full kit (board v6.2 / firmware v6.1) the other day and assembled it this morning.Easy as pie.

I managed to puzzle out (I think) how to get into alignment: hold tuning knob in while powering up. The screen calibrate _everytime_ is annoying. Zerobeating is challenging because there is a second hetrodyne that becomes audible and climbs in frequency *just* as I'm approaching zerobeat. So far, when I tune WWV afterwards, the display read 10,000.05, and I've done it a number of times. Setting the BFO - what's that about? I used an audio spectrum analyzer as 1 post suggested, but - is that all there is to it?

Volume/switch knob: I dealt with that by grinding down about 3/32" of the knob from the radio side of the knob. This allows that setscrew to move further down the switch shaft and it gets much better purchase on the shaft.It just doesn't have the same flare now as the tuning knob.

Please ring in with suggestions.

Thanks and 73
--
Dan D'Eon
AG7GM

Reed N
 

Hi Dan,

If you're using the stock software, you should be able to press and hold (for a LONG time, like 10s) the button after powering the radio on, and it will go to a config menu. You can then change the oscillator and BFO cals at will, without having to do the screen cal.


Reed

Reed N
 

I suppose I should address the cal stuff too.

The main oscillator cal calibrates the frequency generator, which determines how correct all three of the clock outputs from the chip are. The BFO cal adjusts the offset of the second stage, relative to the first, and thus determines where the 45MHz mix ends up relative to the much steeper 11MHz crystal filter. Usually, you'll want the 45MHz to mix down such that the side band of interest falls within the filter's pass band, and the carrier and other side band are not. It's possible to adjust the BFO backwards, so that LSB and USB are reversed. If this happens, you can "undo" it by re-adjusting the BFO cal to the "other" good spot (there should be two places where signal comes through).

If you're finding that you're a bit off of the cals, then I definitely suggest doing iterative tweaks. Tune to 10MHz (or a known AM station), then go into the main cal and tweak it a bit. After doing that, go back and adjust the BFO. Then re-adjust the main cal. Back and forth until you're happy. Note that you'll want to write down the cals each time, since the stock software reverts the cal when you enter the menu (side note: my software doesn't have this problem)


Reed

Dan D'Eon
 

Reed, thanks so much. this was very helpful.
--
Dan D'Eon
AG7GM

Jeff Debes
 

I’m just going to find a smaller knob, It doen’t need to be as large as it is.



On May 28, 2020, at 10:55 AM, pulco.ant@... wrote:

Reed, thanks so much. this was very helpful.
--
Dan D'Eon
AG7GM

--
jeff.debes@...

Arv Evans
 

Dan

It seems that a number of new users of uBITX are not familiar with the "zero-beat" 
process, and not familiar with BFO offset relative to crystal filter bandwidth.  

If doing a zero-beat and your BFO is not properly aligned then the received signal 
will not be placed properly inside the filter passband.  This Allows the opposite 
sideband to be heard over top of the zero-beat.  

Technical info..... When setting the BFO frequency relative to received frequency, 
the BFO should be set approximately 12 db down one side of the crystal filter 
skirt.  Which skirt is determined by which sideband is going through the filter.
You have a DSB signal prior to the filter and setting the BFO 12 db down the 
filter skirt further reduces the unwanted sideband.  Doing this also rolls-off low
frequency audio tones to make your sideband signal more efficient.
The uBITX assembly instructions do include a block diagram that should make 
this easier to understand.  

Arv
_._


On Wed, May 27, 2020 at 10:14 PM <pulco.ant@...> wrote:
Hello. Got my full kit (board v6.2 / firmware v6.1) the other day and assembled it this morning.Easy as pie.

I managed to puzzle out (I think) how to get into alignment: hold tuning knob in while powering up. The screen calibrate _everytime_ is annoying. Zerobeating is challenging because there is a second hetrodyne that becomes audible and climbs in frequency *just* as I'm approaching zerobeat. So far, when I tune WWV afterwards, the display read 10,000.05, and I've done it a number of times. Setting the BFO - what's that about? I used an audio spectrum analyzer as 1 post suggested, but - is that all there is to it?

Volume/switch knob: I dealt with that by grinding down about 3/32" of the knob from the radio side of the knob. This allows that setscrew to move further down the switch shaft and it gets much better purchase on the shaft.It just doesn't have the same flare now as the tuning knob.

Please ring in with suggestions.

Thanks and 73
--
Dan D'Eon
AG7GM

Jeff Debes
 

Great explanation Arv! 
Thanks!


On May 28, 2020, at 1:55 PM, Arv Evans <arvid.evans@...> wrote:


Dan

It seems that a number of new users of uBITX are not familiar with the "zero-beat" 
process, and not familiar with BFO offset relative to crystal filter bandwidth.  

If doing a zero-beat and your BFO is not properly aligned then the received signal 
will not be placed properly inside the filter passband.  This Allows the opposite 
sideband to be heard over top of the zero-beat.  

Technical info..... When setting the BFO frequency relative to received frequency, 
the BFO should be set approximately 12 db down one side of the crystal filter 
skirt.  Which skirt is determined by which sideband is going through the filter.
You have a DSB signal prior to the filter and setting the BFO 12 db down the 
filter skirt further reduces the unwanted sideband.  Doing this also rolls-off low
frequency audio tones to make your sideband signal more efficient.
The uBITX assembly instructions do include a block diagram that should make 
this easier to understand.  

Arv
_._


On Wed, May 27, 2020 at 10:14 PM <pulco.ant@...> wrote:
Hello. Got my full kit (board v6.2 / firmware v6.1) the other day and assembled it this morning.Easy as pie.

I managed to puzzle out (I think) how to get into alignment: hold tuning knob in while powering up. The screen calibrate _everytime_ is annoying. Zerobeating is challenging because there is a second hetrodyne that becomes audible and climbs in frequency *just* as I'm approaching zerobeat. So far, when I tune WWV afterwards, the display read 10,000.05, and I've done it a number of times. Setting the BFO - what's that about? I used an audio spectrum analyzer as 1 post suggested, but - is that all there is to it?

Volume/switch knob: I dealt with that by grinding down about 3/32" of the knob from the radio side of the knob. This allows that setscrew to move further down the switch shaft and it gets much better purchase on the shaft.It just doesn't have the same flare now as the tuning knob.

Please ring in with suggestions.

Thanks and 73
--
Dan D'Eon
AG7GM


--
jeff.debes@...

Ashhar Farhan
 

It seems to me that almost every one jumps into calibration. 
Dont Do That!
It comes precalibrated. But once you have fiddled with it the config menu, then you are in the weeds if you dont know your way around zero-beating.
I have no idea where this myth about calibrating had come from. Probably it is time to include a large printed warning with the kit.
- f

On Thu 28 May, 2020, 11:28 PM Jeff Debes, <jeff.debes@...> wrote:
Great explanation Arv! 
Thanks!


On May 28, 2020, at 1:55 PM, Arv Evans <arvid.evans@...> wrote:


Dan

It seems that a number of new users of uBITX are not familiar with the "zero-beat" 
process, and not familiar with BFO offset relative to crystal filter bandwidth.  

If doing a zero-beat and your BFO is not properly aligned then the received signal 
will not be placed properly inside the filter passband.  This Allows the opposite 
sideband to be heard over top of the zero-beat.  

Technical info..... When setting the BFO frequency relative to received frequency, 
the BFO should be set approximately 12 db down one side of the crystal filter 
skirt.  Which skirt is determined by which sideband is going through the filter.
You have a DSB signal prior to the filter and setting the BFO 12 db down the 
filter skirt further reduces the unwanted sideband.  Doing this also rolls-off low
frequency audio tones to make your sideband signal more efficient.
The uBITX assembly instructions do include a block diagram that should make 
this easier to understand.  

Arv
_._


On Wed, May 27, 2020 at 10:14 PM <pulco.ant@...> wrote:
Hello. Got my full kit (board v6.2 / firmware v6.1) the other day and assembled it this morning.Easy as pie.

I managed to puzzle out (I think) how to get into alignment: hold tuning knob in while powering up. The screen calibrate _everytime_ is annoying. Zerobeating is challenging because there is a second hetrodyne that becomes audible and climbs in frequency *just* as I'm approaching zerobeat. So far, when I tune WWV afterwards, the display read 10,000.05, and I've done it a number of times. Setting the BFO - what's that about? I used an audio spectrum analyzer as 1 post suggested, but - is that all there is to it?

Volume/switch knob: I dealt with that by grinding down about 3/32" of the knob from the radio side of the knob. This allows that setscrew to move further down the switch shaft and it gets much better purchase on the shaft.It just doesn't have the same flare now as the tuning knob.

Please ring in with suggestions.

Thanks and 73
--
Dan D'Eon
AG7GM


--
jeff.debes@...

Evan Hand
 

I agree that many will jump into the calibration process before needed.  I would add to the waring to MAKE SURE IT WORKS AS DELIVERED BEFORE MODIFICATIONS!  This includes the calibration steps. 

We have seen a number of issues on the board that are solved with BFO adjustments, not calibrating.  As you have stated, recalibration of the system frequency is rarely needed.  BFO adjustments more so, in my opinion, and personal experience.

I have built 3 kits, 2 v4, and one v5.  For the second version 4, I went right into a mod without first making sure that it worked.  I ultimately went back to the as-delivered state, got it working (I had some cold solder joints), and then started the modification.  I would have saved a lot of headaches if I had followed my own advice.

FWIW, and YMMV
73
Evan
AC9TU

R. Tyson
 

I got a version 5 late last year. Put it into a case of my own choosing. Fired it up, checked it out and went on to make QSO's with it. Never did need to alter the tuning - it just worked as was. Added a CW filter and it is a great rig.

Why complicate it if you don't need to ? Use it and admire it.

Reg                   G4NFR

k7ks1@...
 

Thanks, great info gentlemen.   When I received my V6, I got no audio or power out using the microphone on SSB and was quite concerned.   I took the advice of several of you and did the BFO adjustment and only after doing that, did SSB give me  power out.   So it may arrive Precalibrated, but mine did not work properly until I calibrated it.      thanks again gents.

Alan   K7KS

Alex Netherton
 

Alls I can say is - wish I had had the same experience. Got m ine for Christmas, have only managed receive so far. Got disgusted in Feb somewhere and stored it before i threw it against a brick wass to "fix" it. Will likely get it back out and see if I can get the BFO and receive notch dialed in. THEN, I will work on bias.
Honestly, I wish I had bought a cheap Chinese rig and just put it on the air.
73 de W5ALX

On 6/23/2020 1:31:55 PM, R. Tyson via groups.io <tysons2@...> wrote:

I got a version 5 late last year. Put it into a case of my own choosing. Fired it up, checked it out and went on to make QSO's with it. Never did need to alter the tuning - it just worked as was. Added a CW filter and it is a great rig.

Why complicate it if you don't need to ? Use it and admire it.

Reg                   G4NFR

Bob Lunsford
 

For me, the problem with a "cheap Chinese rig" is that you have a problem finding schematics for them and I was afraid of using on for a couple of years or so , finding it souring on me and then discovering the "fix" was to buy a new one. I have no proof that the Chinese rigs, like the ones sold by MFJ (the G90 and 5105), have built in obsolescence and don't think they do since a lot of Chinese hams are buying them. And they do have attractive specs. BUT, you learn quickly that if you are budget oriented at all, the V6 is much more rewarding considering what you get for it with price a high priority in the decision.

I like the looks of the full-kited V6 and do enjoy QRP without all the bells and whistles like I did with the HW-7s and -8s. The fact that the V6 can receive AM and SW broadcast stations (zero beating) also is a draw for me.

If/when I win the lottery, it will then that I will take another look at the Chinese offerings.

Bob — KK5R

On Tuesday, June 23, 2020, 3:26:56 PM EDT, Alex Netherton via groups.io <w5alx@...> wrote:


Alls I can say is - wish I had had the same experience. Got m ine for Christmas, have only managed receive so far. Got disgusted in Feb somewhere and stored it before i threw it against a brick wass to "fix" it. Will likely get it back out and see if I can get the BFO and receive notch dialed in. THEN, I will work on bias.
Honestly, I wish I had bought a cheap Chinese rig and just put it on the air.
73 de W5ALX

On 6/23/2020 1:31:55 PM, R. Tyson via groups.io <tysons2@...> wrote:

I got a version 5 late last year. Put it into a case of my own choosing. Fired it up, checked it out and went on to make QSO's with it. Never did need to alter the tuning - it just worked as was. Added a CW filter and it is a great rig.

Why complicate it if you don't need to ? Use it and admire it.

Reg                   G4NFR

Stephen KO4CVU
 

Alex,
If you haven't already, make a "perfect pitch" with the Baofeng microphone. (That's when you throw it and it goes straight to the bottom of the trash can without touching the sides.) Buy a CB microphone with a built-in preamplifier. It made a big improvement on my SSB phone output, but I have not been able to achieve the power output that  Ashhar says he can get (see his post #48203.)
Stephen

Richard West
 

Well Bob,

I have a defective G1M doorstop in the box. It had experienced a catastrophic power event, among other manufacturing problems. Mailed it back to China, only to get the same radio on the doorstep just as broken as when it was shipped USPS for $85.00. Been there, done that, but not again. Spent more time in transit than in the shack.
There is a UBITx V4 of mine that is physically in bits and pieces in the junk box zipped into a ziplock bag. Became so frustrated with all the time, effort, energy, and money spent it became a job, not a hobby. It never worked right, even though help was requested, and received. 

Still think of the countless, fruitless hours spent on that unit with many regrets. Have moved on to an HW-8, with the HWA-7-1, or use the TS-440SAT with power dialed down to 10 watts with satisfaction. 

The equipment we use is like anything else, we make informed decisions, and then make choices.

73,
Wes/KH2EE

Gordon Gibby
 

Different strokes for different folks!
This is just not your cup of tea 
Find something different, MoveOn and enjoy yourself.   


On Jun 23, 2020, at 16:12, Stephen KO4CVU <goinfishin1952@...> wrote:

Alex,
If you haven't already, make a "perfect pitch" with the Baofeng microphone. (That's when you throw it and it goes straight to the bottom of the trash can without touching the sides.) Buy a CB microphone with a built-in preamplifier. It made a big improvement on my SSB phone output, but I have not been able to achieve the power output that  Ashhar says he can get (see his post #48203.)
Stephen

MVS Negi
 

I assembled my V6 rig. Works fine but the freq indicated is off the actual freq. How do I correct this? Pressing the Tuning Encoder knob does nothing to the menu...
Need advice !
Mahendra

On Wed, Jun 24, 2020 at 6:43 AM Gordon Gibby <docvacuumtubes@...> wrote:
Different strokes for different folks!
This is just not your cup of tea 
Find something different, MoveOn and enjoy yourself.   


On Jun 23, 2020, at 16:12, Stephen KO4CVU <goinfishin1952@...> wrote:

Alex,
If you haven't already, make a "perfect pitch" with the Baofeng microphone. (That's when you throw it and it goes straight to the bottom of the trash can without touching the sides.) Buy a CB microphone with a built-in preamplifier. It made a big improvement on my SSB phone output, but I have not been able to achieve the power output that  Ashhar says he can get (see his post #48203.)
Stephen

Reed N
 

Mahendra,

With the stock software, you need to press and HOLD for ~10 seconds before the menu will come up. Then you can adjust your oscillator cal to zero beat.


Reed

MVS Negi
 

I tried that, nothing happens...Checked with my friends on the Air, I find the freq out by different amount on different Bands. It is disconcerting. The receiver is pretty good though. 
Thanks

On Wed, Jun 24, 2020 at 1:04 PM Reed N <greenkid336600+groupsio@...> wrote:
Mahendra,

With the stock software, you need to press and HOLD for ~10 seconds before the menu will come up. Then you can adjust your oscillator cal to zero beat.


Reed

Evan Hand
 

Please review the following video before you do the calibration.  As is stated in this thread, it is very easy to get it wrong, and then can be difficult to get it back to working.

Since you have determined that it is off frequency, here is how Ashhar Farhan suggests recalibrating:
https://www.youtube.com/watch?v=t6LGXhS4_O8

73
Evan
AC9TU