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Re: Spectrum purity of uBITX and BIT40

 

?I notice that nobody mentions the best way to check an SSB outgoing signal.
?You need a good two tone audio signal generator. Along with a wide band scope, check that you see a good sine wave pattern.
?We had a setup for testing SSB CB Radios that did just this, so we could see how good the pattern was,
?The setup also checked an AM signal modulated with a single tone.
?You wanted a nice even sine wave. No flat topping, which meant over modulation, and modulation to a bit under where it would start to flat top
?this gave you the cleanest signal.
?Even on ham frequencies, you want the same results
?Make sure that the audio signals are a nice clean sine wave.
?Mixed with a nice clean signal on AM.
?I would say best to check the carrier on AM, as well as the audio sine waves for a nice clean sine wave.
?A square wave is not what you want to use for these tests.

?Wayne WA2YNE

On Sun, Dec 2, 2018 at 5:29 PM Mark McNabb <n7eku@...> wrote:

Hi Simon,

I don't think this is true.? What is true with homebrew, is that the device doesn't not have to be tested by the FCC; the spectral requirements are still the same, but it is up the the user to figure out how to meet them.? That is where the "test, training, education, etc." comes into play!

73,


Mark.
Re: uBITX - Limiting power output

 

Nice to point out that existing pot. I suggest leaving it there, lift one leg and try a second pot in series on front or rear panel to trim the output power. Just he careful to route coax around the board so it does not compromise the filters or provide other unwanted leakage, I think this is the greater challenge.

I used the 1208 until I zapped the preamp. Also mine was an early one with a poor quality circuit board, but it could be restored if I ever have use for it. yes I had also thought 2 watts to be optimal drive.

Curt
Re: 7277 Bitx >Bitx Today 12/2/18

 

I have had that same issue and would recommend 7180.

Evan
AC9TU
Re: uBITX - Limiting power output

 

You could add relays and pots to adjust power across bands.? I'm thinking about using the current system for 'max out' and a second layer for 'max 5W out' when feeding my WA2EBY.



Andy, KG5RKP


On Sun, Dec 2, 2018 at 06:50 PM, Charles French wrote:
Thanks for the feedback from all of you.
?
Allison, I wonder if that pot could be brought out to the front panel using some silver/teflon coax for the round trip without creating too many isues? Or is that just asking for trouble?
?
Thanks again!

On Dec 2, 2018, at 1:30 PM, Jim Sheldon <w0eb@...> wrote:
?
Don't know for sure. ?Christmas party this afternoon so be tomorrow before much else gets done.

On Dec 2, 2018, at 12:12 PM, AndyH <ahecker@...> wrote:

The stock ?BITX has a drive adjustment at RV1 - the pot that follows the first stage in the RF chain (Q90).? I've used mine to drive a WA2EBY amp on 40 meters and adjusting RV1 was all it took to drop the peaks to 5 W.??

Andy, KG5RKP?
Re: uBITX - Limiting power output

 

¿ªÔÆÌåÓý

Thanks for the feedback from all of you.

Allison, I wonder if that pot could be brought out to the front panel using some silver/teflon coax for the round trip without creating too many isues? Or is that just asking for trouble?

Thanks again!

On Dec 2, 2018, at 1:30 PM, Jim Sheldon <w0eb@...> wrote:

Don't know for sure. ?Christmas party this afternoon so be tomorrow before much else gets done.

On Dec 2, 2018, at 12:12 PM, AndyH <ahecker@...> wrote:

The stock ?BITX has a drive adjustment at RV1 - the pot that follows the first stage in the RF chain (Q90).? I've used mine to drive a WA2EBY amp on 40 meters and adjusting RV1 was all it took to drop the peaks to 5 W.??

Andy, KG5RKP?

Re: 7277 Bitx >Bitx Today 12/2/18

 

There is a strong broadcast signal on 7275 which is putting a fairly strong carrier on 7277.? Not good for weak signal work.?? Seems to me the calling frequency should be moved to someplace below 7200 and above 7175 to get away from the broadcast signals.? General class licensees can operate SSB starting on 7175.

Jim
W6yxy
Re: UbitX audio hiss but no rx

David Berkompas
 

I had the same problem.
(Well, at least I thought I did, turns out it was a PICNIC error).

Put the radio in CW mode, and find an AM station.

Hope that helps.

Dave - AI6K
Re: Spectrum purity of uBITX and BIT40

Mark McNabb
 

Hi Simon,

I don't think this is true.? What is true with homebrew, is that the device doesn't not have to be tested by the FCC; the spectral requirements are still the same, but it is up the the user to figure out how to meet them.? That is where the "test, training, education, etc." comes into play!

73,


Mark.
Re: Spectrum purity of uBITX and BIT40

 

Seem to hear that self build, home brew is more relax under fcc laws than mass production factroy machine, to allow progress in test, training, education, etc., in principle. ??

Still want to emit a as clean as possible signal, for common good

73 Simon


On Monday, December 3, 2018, Simon via Groups.Io <simonhk7=[email protected]> wrote:
If i buy a new one, is the good relay come with present version??

Or it is consider a user mod, that i need to buy my own good relay

73 Simon

On Monday, December 3, 2018, ajparent1/KB1GMX <kb1gmx@...> wrote:
Clark,

Its not solely the relays.? Its also the interaction of the pcb routing of the interconnects.
lower the C of the contacts or better routing and the problem disappears.

Since the bitx40 is monoband it has none of those issues and is much cleaner.

Allison

Re: Spectrum purity of uBITX and BIT40

 

If i buy a new one, is the good relay come with present version??

Or it is consider a user mod, that i need to buy my own good relay

73 Simon


On Monday, December 3, 2018, ajparent1/KB1GMX <kb1gmx@...> wrote:
Clark,

Its not solely the relays.? Its also the interaction of the pcb routing of the interconnects.
lower the C of the contacts or better routing and the problem disappears.

Since the bitx40 is monoband it has none of those issues and is much cleaner.

Allison

Re: uBitx Function Button ERROR

 

Rf pickup on adc can be observe by loading an adc read arduino program, on serial monitor. Use handheld 2m tx with ant near the push button and wiring

73 Simon


On Monday, December 3, 2018, Simon via Groups.Io <simonhk7=[email protected]> wrote:
Connect multiple thick ground wire from pcb , said rf plug, to multiple point of case, for each piece of casing metal plates. Contact between metal plate is not fully reliable, in strict sense.?

73 Simon

On Monday, December 3, 2018, Evan Hand <elhandjr@...> wrote:
I had the same issue with a metal case.? The interesting thing for me was that on a single band 20m dipole I did not have the issue.? When I connected to a tri band (40/20/10) I started having the problem, only on 20m.? Solved it with grounding of the coax shield and ferrite clip ons.

What type of antenna are?you using?

Evan
AC9TU???
Re: Is push pull hf amp has higher spectral purity

 

¿ªÔÆÌåÓý

Garbage in, garbage out.?


MRM

?


On Dec 2, 2018, at 3:40 PM, iz oos <and2oosiz2@...> wrote:

The push pull has the advantage to deeply attenuate the even harmonics, all versions of the ubitx were good in that, the issue was on odd harmonics, 3rd, 5th.... With push pull a less steeper low pass filter can be used. Especially the 'corner'? frequency can be chosen higher than it would be otherwise. A single low pass filter can also be used for a couple bands. So you save a lot in filtering and relays, it's more a matter of cost and convenience I believe. Monoband qrps are much easier, the ones I had assembled don't have a push pull final, just a normal amplifier and a low pass filter to remove any harmonics. Maybe even I could design a monoband transceiver...


Il 02/dic/2018 20:18, "Simon" <simonhk7@...> ha scritto:
Is push pull generally has higher spectral purity than single end transister ? ? Ubitx is push pull, bitx40 is single end.

I read comments stating that bitx40 has better spectural than ubitx, because it is single band, simpler circuit. Is it true for present batch, revision?? I meant, the comments could refer to many revisions over time. ?

How "bad" is the situation? It is not too far from fcc spec., right? There were quite a number of posting on spectural purity? Is the latest batch solved the issue now.?

73 Simon


--

¡­_. _._
Power for continuous digimode

 

As is kit without mod, How much power output is ubtx and btx40, for 100 percent continuous digimode?

Should i use a larger heat sink?

Can output higher with higher voltage and bigger heatsink, for 100 percent on duty cycle?

73 Simon
Re: uBitx Function Button ERROR

 

Connect multiple thick ground wire from pcb , said rf plug, to multiple point of case, for each piece of casing metal plates. Contact between metal plate is not fully reliable, in strict sense.?

73 Simon


On Monday, December 3, 2018, Evan Hand <elhandjr@...> wrote:
I had the same issue with a metal case.? The interesting thing for me was that on a single band 20m dipole I did not have the issue.? When I connected to a tri band (40/20/10) I started having the problem, only on 20m.? Solved it with grounding of the coax shield and ferrite clip ons.

What type of antenna are?you using?

Evan
AC9TU???
Re: uBITX - Limiting power output

 

Charles French,

just back down RV1 on the bitx.? or better yet start at 0 (FYI its counter-clockwise to max not min
as its backward) and run it up till the 1208 gives full power using CW.? Since the bitx does not?
have alc it has no issues with spiking power.

FYI I have the 1208 and depending on what values were installed the internal attenuator could
be 5W or lower. Too much power and you fry the mixer diodes.

Mine was optimum with about 2W and I'd get about 11W SSB out with a 13.8V supply.
The driving radio was HB 20M and used it for years that way.? Now it serves standby
in case the main radio (TT 6n2) gets ill.

Allison
Re: Is push pull hf amp has higher spectral purity

 

So, for current version that if i buy today, is it basically true that the overall story is?

1. btx40 is just meeting fcc spec, i believe is 50dBc for lower freq,

2. Ubtx is just a bit short, but not too far

73 Simon


On Monday, December 3, 2018, ajparent1/KB1GMX <kb1gmx@...> wrote:
Simon,?

The structure of the amp is not the sole element of the question.? I have a single ended that beats the push-pull
of the ubitx by miles.? I also have a QSX amp that is push pull and is very clean.? In the end its not if A or B
but how well the design was executed.

Right now the V4 ubitx solves no issues over the V3 save for now it does not use the TDA2822 audio amplifier chip.

Allison

Re: uBitx Function Button ERROR

 

I had the same issue with a metal case.? The interesting thing for me was that on a single band 20m dipole I did not have the issue.? When I connected to a tri band (40/20/10) I started having the problem, only on 20m.? Solved it with grounding of the coax shield and ferrite clip ons.

What type of antenna are?you using?

Evan
AC9TU???
Re: uBitx Function Button ERROR

 

Is there a publicly published circuit diagram for the push button and tuning knobs, connect to p1 of radioduno, that marked as a0 to a?, analogue input.

Some switch use adc, switch resistor, so each push button produce different voltage. Hence, one line for many switch. As in dfrobot arduino lcd and switch plug in,widely used.

Chip input line can pick up rf and rectify it as analogue voltage. Put 0.1uF on the adc line normally work, if it use the adc design as above. Tie the switch wiring away from rf final pa area. In extreme case, use screen cable and copper fold wrapping, as in one of my work case.? Since the kit use normal cable, likely tie it away ftom rf pa is enough

73 Simon


On Monday, December 3, 2018, iz oos <and2oosiz2@...> wrote:

Ground loop somewhere? Is it connected with other stuff except the antenna?


Il 02/dic/2018 20:31, "Daniel" <gonewiththeego@...> ha scritto:
Hello everyone! I have a case from an old 2m transceiver and I decided to use it for my uBitx. Everything is fitting well, I am proud of what I accomplished. I have a big, BIG problem. Whenever I push to talk and I start talking into the microphone, the function menu is appearing for I don't know what reason. Only when I speak!? I have checked the wiring for a hundred of times, still no mistake. It's actually the same wiring I used in the old plastic case which worked flawless. This one is a metal case. I also soldered the antenna coax to the output of the uBitx because I suspected it has something to do with some RF leaking or so, I don't know. For the record, I would like to point that when I keep my hand on the output plug, the menu function is not appearing. I twisted all the wires, in separate pairs, audio and digital, still the same. I would strongly appreciate ANY kind of information because right now I'm out of solutions for this. Maybe only erasing the menu function from the firmware, but this is Kalashnikov. Thanks!

Re: Is push pull hf amp has higher spectral purity

 

Simon,?

The structure of the amp is not the sole element of the question.? I have a single ended that beats the push-pull
of the ubitx by miles.? I also have a QSX amp that is push pull and is very clean.? In the end its not if A or B
but how well the design was executed.

Right now the V4 ubitx solves no issues over the V3 save for now it does not use the TDA2822 audio amplifier chip.

Allison
Re: Spectrum purity of uBITX and BIT40

 

Clark,

Its not solely the relays.? Its also the interaction of the pcb routing of the interconnects.
lower the C of the contacts or better routing and the problem disappears.

Since the bitx40 is monoband it has none of those issues and is much cleaner.

Allison
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