Date   

RF out

Mike Short <ai4ns.mike@...>
 

I added an SMA connector instead of the existing connector. Should help with stray RF.
--
Mike
AI4NS


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

Ah, correction:

I saw somewhere that spurious emission OF UBITX is at the level of -45dB toward the fundamental frequency.

// hiro



2018/07/31 12:04、hirosmb <hirosmb@...>のメール:

Christopher,

I saw somewhere that spurious emission is at the level of -45dB toward the fundamental frequency.

However, Japan’s latest spurious regulation requires more than -50dB and so I started thinking about pi-match tuner or BPF.

This doesn’t mean that uBitx doesn’t suppress good enough spur but it just means that Japan’s regulation is a little tight, I suppose.

// hiro, JJ1FXF



2018/07/31 5:14、Christopher Miller <djmalak2k6@...>のメール:

Would they not just need band pass filters for whatever the desired band is? I kind of see where you might be able to suppress spurious emissions in a tuner, but why? My limited understanding is that the ubitx has filters for hf bands 20 meters and lower. Do they not provide enough suppression?  If not a filter should be pretty straight forward to construct. No?


CW keyer issues#ubitxcw

Mike Short <ai4ns.mike@...>
 

I am having issues with the keyer.  I will only use paddles for CW. Tip is dit, I connected the 2.2k to it. The middle contact is dah, connected the 10k to it. Other ends of the resistors are soldered together with the blue wire. The 4.7k is connected to the dit, and them to the green. What did I do wrong? I only get dahs, 
--
Mike
AI4NS


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

Christopher,

I saw somewhere that spurious emission is at the level of -45dB toward the fundamental frequency.

However, Japan’s latest spurious regulation requires more than -50dB and so I started thinking about pi-match tuner or BPF.

This doesn’t mean that uBitx doesn’t suppress good enough spur but it just means that Japan’s regulation is a little tight, I suppose.

// hiro, JJ1FXF



2018/07/31 5:14、Christopher Miller <djmalak2k6@...>のメール:

Would they not just need band pass filters for whatever the desired band is? I kind of see where you might be able to suppress spurious emissions in a tuner, but why? My limited understanding is that the ubitx has filters for hf bands 20 meters and lower. Do they not provide enough suppression?  If not a filter should be pretty straight forward to construct. No?


Re: End Fed antennas w/ uBITX #ubitx

ajparent1/KB1GMX <kb1gmx@...>
 

John,

Two ways.... peel away the goop and see.  the 1:1 is obvious.

The 1:9 if its really 1:9 put a 450ohm resistor (a 470 will do in a pinch) from the output terminal
to the coax ground with short leads.  The use an antenna analyser if its 1:9 then he reflected
SWR will be 1:1 or ver very close.

The inductance can only tell you the number of turns of the trifilar bundle.  To get that you need
the ferrite type and size and use one of the kits and parts calculators for that ferrite and do it by trial.
IF expect between 6 and 9 turns of the triple wires.

Did you look at the ERACHI End fed kit manual posted earlier today? it makes that 1:9 transformer.

Allison


Re: End Fed antennas w/ uBITX #ubitx

John Smith
 

Hi Allison, I have been looking at how 9:1 are wound and most of them look like the example you shared, except for one and it kinda matches what I have. I have a twisted trifilar 4 wraps transformer but it's smaller than the example I found at - https://myantennas.com/wp/product/91-unun/ I am including a picture, the one on the left is the new 9:1, and the right is the 1:1. And the inductance I didn't measure before is 197uH between posts on the 9:1. Is there an old school way to determine rf impedance with these measurements or does that require specific test equipment? Or am I fussing too much about something that's probably fine anyway? It's new territory.


Re: End Fed antennas w/ uBITX #ubitx

ajparent1/KB1GMX <kb1gmx@...>
 

Chuck,

Right on point.  You nicely summarized methods and process of antenna development
in an antenna engineering firm I worked for.

Use case, establish what you need the antenna to do.   Also try to not succumb
to excess added features.   The other side of that is no antenna need be forever,
so try different things to meet the need. That includes ways to easily to raise and
lower antennas.

Design/build/evaluate/modify process is a well known engineering procedure
to developing a functional product.  To that I add conceive and evaluate candidates
as that is where the process is process started.  Its research, look at antennas and 
try to understand what they can do in a specific case.   Not all candidates pass
muster but one may be the diamond.   Also failures can evolve to be the niche
solution rather than the general.

Simplicity, within the bounds of fitness for the design purpose.  
Always keep in mind the goal.   And if all else fails, KISS, then build it well.

All to often antennas are a target of magic thinking or outrageous claims. 
Substance is measurable, construction quality, material quality, applicability
and frugality.  The latter is not "is it cheap" but "is it a good value".


Allison


Re: Raduino Pill

W3JDR
 

I got some time to build up the power managememt, Si5351 and LCD sections. 
Updates are posted to:
www.w3jdr.com


Re: End Fed antennas w/ uBITX #ubitx

ajparent1/KB1GMX <kb1gmx@...>
 

Indeed it does for many people.

The test method is not as exhaustive as I'd expect but...  2450/800=3.mumble
as a SWR is low enough to be a measurement that can be used at the qualitative
level and with a compensating calculation would net quantitative evaluation.  I
suspect they wanted to run power through it as a lowly 2500 ohm 2 watt would
have done for simple testing.

Allison
 


Re: Spurious RF at beginning of CW transmission in the uBitx

ajparent1/KB1GMX <kb1gmx@...>
 

Bob, 

Good work.  There was an earlier fix that tackled the fact that there is no pulldown 
for the open contact its used two cross coupled 3904s to short the unpowered line RX+ or TX+.
The side effect there are enough big caps that do not discharge fast.

I believe the ubitx  fixes site has it, yes it does. Full description there...

https://ubitx.net/category/audio-pop-mod/page/2/


Re: hacking bitx40 for 20 metre #bitx40

mangrove@...
 

On top of changing the BPF and the LO, you may have to change the BFO frequency (depending on which new VFO range you pick) and move it to the other edge of the IF pass band filter since 20m ham SSB uses USB.

Thang AA6SV


Re: End Fed antennas w/ uBITX #ubitx

Warren Allgyer <allgyer@...>
 

Kickoff!

Read the review. Understand it is not an ARRL sanctioned review and was not done by their lab. Understand the efficiency measurement methodology was completely wrong. Other than that the review is fine. The antenna will make contacts.

WA8TOD


Re: Spurious RF at beginning of CW transmission in the uBitx

Arv Evans
 

On Mon, Jul 30, 2018 at 01:39 PM, <n1kw@...> wrote:
Bob N1KW

Every since the first BITX we have griped and complained about the 20 ms infamous "BITX Click"
that occurs in changing over from receive to transmit and from transmit to receive.  Earlier tests
indicated that it was somehow associated with hold-over voltage on capacitors between audio circuits
and the balanced modulator.  Is it possible that you have now found, and fixed, that long-standing
problem?

It appears that I have solved the problem! While analyzing the circuit further, I realized that the
large capacitor C52, which is charged during receive, would feed back through R52 and R18
keeping the receive path (Q10, 11, and 12) after the balanced modulator "hot" for a brief period.
When the transmit path is activated, the receive side of the circuit is going to remain on for some
period of time due to the time constants of C52 and its loads. It is understandable that if both
directions of the circuit are on, it could oscillate during that time!


To resolve the issue I simply added a diode in series with R52 (cathode toward C52) so that C52
can no longer back feed power to Q10, 11, and 12 upon initiation of transmit state. Now the transmitter
output looks perfectly clean on the spectrum analyzer at beginning if TX. Shorting the diode causes
the problem to show as before.


If this fixes that long-standing problem, then we all owe you a big THANK YOU

Arv K7HKL
_._


Re: BITX40 relay K1 AND q13

Nick VK4PP
 

HI Denis,

I do seem to remember this has come up before in the past, not sure what the outcome was, try a search, maybe something... I do like the idea of separating TX and RX even more...

73 Nick VK4PLN


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

You are right, Allison-san.

There should be a possibility of lower spurs on uBitx.

Thank you for letting me know it.

// hiro, JJ1FXF



2018/07/31 7:50、ajparent1/KB1GMX <kb1gmx@...>のメール:

Hiro san,

The NCO (form of synthesis) is very clean save for harmonics due to square waveform.

However there are three oscillators and mixers and the resulting combines can and do
create spurs.

Allison


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

“Not for a long time in prison” is a Good news, Iz. :)

Yes, I like 15m, too.

// hiro, JJ1FXF



2018/07/31 7:41、iz oos <and2oosiz2@...>のメール:

I don't think you will be imprisoned for a long time because of the spurs and the harmonics of the Ubitx unless, as Allison pointed out elsewhere, you use the ssb mode above 20Mhz.


Il 31/lug/2018 00:20, "hirosmb" <hirosmb@...> ha scritto:
Allison-san,

Thanks a lot for your info.

I am checking those presented URLs and a bit surprised with a huge filter using PC case. :)

In my understanding, because uBitx uses DDS and so is not likely to produce lower harmonics such as by frequency multiplier, but higher harmonics may occur in most cases.

Also I am afraid that the fixed BPF or LPF (such as until 30MHz) may not suppress the second harmonics (14MHz) when emitting 7MHz CW, but hoping that the pi-match antenna tuner may work for this case.

// hiro, JJ1FXF



2018/07/31 0:07、ajparent1/KB1GMX <kb1gmx@...>のメール:

Hiro san,

A pi type tuner is generally in the same form as Low pass filters.  As such it can help with harmonics
but lower frequency spurious outputs it will be less helpful.

What you likely want is a transmitting band pass filter then an antenna matcher after that.
Two sites that may be more helpful.  

https://www.n1nc.org/Filters/

http://orarc.net/RF-Filters-2.pdf

Allison


Re: Spurious RF at beginning of CW transmission in the uBitx

n1kw@...
 

Thanks Gordon! I have a simple solution in mind for the keying shape issue. I'll try it and, if it works, I will post it under a new thread.

73, Bob N1KW


Re: Gamma-matching antenna tuner

ajparent1/KB1GMX <kb1gmx@...>
 

Hiro san,

The NCO (form of synthesis) is very clean save for harmonics due to square waveform.

However there are three oscillators and mixers and the resulting combines can and do
create spurs.

Allison


Re: The dreaded LSB and USB swap problem again

 

Dan,

We are using KC8CEC's firmware 1.08 or above along with KC8CEC's uBitx Memory Manager to tweak the calibration settings. If you used the stock firmware to set your calibration you are probably out in no man's land. Mine was so far out I couldn't get control of it until upgraded the firmware and used the memory manager, then it's relatively easy once you figure out that the mystery Master Calibration number in the memory manager doesn't mean anything, you just keep changing it one way or the other from the the base settings until you get the results you want. Others have accomplished calibration by other means that i didn't understand, like the zero beat method which never worked for me. The calibration process is the weak link in the whole uBitx design, we keep adding all these awesome features to the firmware while the Cal process stays broken, IMO.

Joel
N6ALT


Re: Gamma-matching antenna tuner

iz oos
 

I don't think you will be imprisoned for a long time because of the spurs and the harmonics of the Ubitx unless, as Allison pointed out elsewhere, you use the ssb mode above 20Mhz.


Il 31/lug/2018 00:20, "hirosmb" <hirosmb@...> ha scritto:
Allison-san,

Thanks a lot for your info.

I am checking those presented URLs and a bit surprised with a huge filter using PC case. :)

In my understanding, because uBitx uses DDS and so is not likely to produce lower harmonics such as by frequency multiplier, but higher harmonics may occur in most cases.

Also I am afraid that the fixed BPF or LPF (such as until 30MHz) may not suppress the second harmonics (14MHz) when emitting 7MHz CW, but hoping that the pi-match antenna tuner may work for this case.

// hiro, JJ1FXF



2018/07/31 0:07、ajparent1/KB1GMX <kb1gmx@...>のメール:

Hiro san,

A pi type tuner is generally in the same form as Low pass filters.  As such it can help with harmonics
but lower frequency spurious outputs it will be less helpful.

What you likely want is a transmitting band pass filter then an antenna matcher after that.
Two sites that may be more helpful.  

https://www.n1nc.org/Filters/

http://orarc.net/RF-Filters-2.pdf

Allison