Date   

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


Re: uBitX SSB transmit oscillations on 20m only #ubitx

Bruce
 

No mods yet, Raj. I wanted to make it work without adding mods. I'll check K3. I'll also try a .001ufd capacitor across the mic jack once I find one in my collection.


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

Arv,

Thanks for your comment.

Yes, as Timothy said, I was completely confused that there would have been a gamma-match manual antenna tuner which could have been placed just after the RF output of rig.

All what I want is a manual antenna tuner which also works as a LPF, that is to say, a pi-match antenna tuner.

BR,

// hiro, JJ1FXF



2018/07/31 3:00、Arv Evans <arvid.evans@...>のメール:

There are a great many articles available on-line for Gama Match Antenna.
Do a Google search for "gamma match antenna" to see what is available. 

Arv  K7HKL
_._

On Mon, Jul 30, 2018 at 2:08 AM Timothy Fidler <engstr@...> wrote:
Hiro,  suggest you look at  ARRL antenna HB . You should be able to find some PDF on line .....copyright breach and all. (this was supposed to be a  PM But what the Heck)

Gamma match generally used only on 2m and above. ONe side of your coax goes directly to the driven ele dipole side A.

Other side goes to  a rod that lines away from the side b but  paralled to  it. THis can be a  solid rod or of the same round stock as the driven element.

There are two PE or PP plastic elements holding the rod away from the B side driven element.  The rod can be slid back and forth along the B element  to get the best possible coupling.

THe exact stand off  distance and rod length  are a black art .  You never try to test or tune up this stuff except at low power or reduced V on finals.

THe coupling into the B side is capacitive and inductive  and distributed.  Hence black art.  It is hellish unlikely you will get this to work with anything other than a Yagi antenna.

Do you have a 1:1 balun in line as in current balun. If you have harmonics in your transmitted signal this will help the issue of return down the outside of your coax  and that will help keep any harmonics forced into the antenna where since they are not resonant , will be somewhat suppressed.   Voltage baluns can be work of the devil and for VHF accept nothing less than type 61 material in the balun core. Above 150 Mhz you cannot even have type 61 because it is getting very lossy but only your tests with a FSMeter will show what the difference is.

cheers New member -
A and B sides are whatever you define them to be - as above.

 

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885, 
Telephone Whangarei   022  691 8405
e: Engstr@...



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

To:
<BITX20@groups.io>
Cc:

Sent:
Sun, 29 Jul 2018 23:57:39 -0700
Subject:
[BITX20] Gamma-matching antenna tuner


Hi, all.

 

I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japans new spurious regulation.

 

BPF will be fine but I need to make number of coils, right?

 

Then, can anyone point me out where I find some schematics of the Gamma-Matching tuner, or kit of it is very much appreciated.

 

Thanks in advance.

 

// hiro, JJ1FXF


Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

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: End Fed antennas w/ uBITX #ubitx

iz oos
 

Yes you may infer some things and guess and sometimes the type of the transformer. You can grossly guess also the material chemistry of the core. Suppose you have an unknown transformer and you read 50uH at the SO239 and 450uH between the antenna terminals. The ratio is 9:1, 50uH at the SO239 indicates the lowest frequency is around 160m and the core cannot be made of powdered iron. Most likely is ferrite. If you find that there is no dc short at the SO239 and you find around 50uH across the pin of the SO239 and one of the terminal and between the outer of the SO239 and the other terminal you have a 1:1 balun, i.e. a choke which will be fine for all the HF.

Now an annedocte. A friend of mine bought for 80 euro from a Ham, a monoband wire antenna with a black box but found difficult to tune. He didn't want to open the black box as he was afraid of breaking it, he paid a lot for it! Well, the inner of the SO239 was not shorted so I excluded it was a 9:1 transformer, I thought the black box contained a 1:1 choke, I mean a quite expensive one. But then I asked to measure the inductance between the inner of the SO239 and the wire and between the outer of the SO239 and the clamp. In both cases it was 0uH!!!..... He paid 80 euro for 20 meters of ordinary unipolar wire and an empty black box!!!!


Il 30/lug/2018 20:33, "John Smith via Groups.Io" <johnlinux77=yahoo.com@groups.io> ha scritto:
The inductance meter reads 97uH to antenna, and 38uH to ground. The first one I bought that looks like this model and is a 1:1 balun has shielded cable to the toroid and shrink wrapped magnet wire wrapped around it, and looks professional. The inductance readings on the 1:1 balun are 49 and 53uH. This 9:1 unun looks like the typical knock off crap made in the back of a Shenzhen market stall with white shmoo hiding the lies. Are these inductance readings something you expected to see, or way off?


Re: End Fed antennas w/ uBITX #ubitx

Jerry Gaffke
 

If you are into placing your radiation pattern exactly where you want it with a big yagi,
then a multiband wire antenna is not for you.  Agreed.

But many hams are putting up a wire dipole as best they can fit it on the lot
into what trees are available.  The radiation pattern is what it is. 
An EFHW at the fundamental can work about as well as the more typical dipole
with the same radiation pattern, and is easier to put up for mechanical reasons.
As a bonus, in my experience it can work very well as a multiband antenna as well.
The many lobes at the harmonics actually are not a negative, the dipole isn't 
efficient all directions either.   Most of us don't have a rotater for our 80m dipole. 
Fundamental or harmonics, I'm primarily concerned that it radiate efficiently.
If it happens to have a pipeline into Timbuktu and not LA, I'm fine with that.
If you don't like the direction it is pointed, try another band and it's a whole new ball game.

Trying to make an EFHW into an efficient multiband antenna can be tough.
That's why this thread now has 250+ posts.
Rather than kick off another storm of posts here, I'll just suggest you read
the EFHW-8010  review in the March 2016 edition of QST.
That review squares well with my experiences of that particular antenna.
       http://www.arrl.org/files/file/ProductReviewsForDeb/2016/pr032016.pdf

Jerry, KE7ER



On Mon, Jul 30, 2018 at 01:44 PM, Chuck, N1KGY wrote:
Agreed on both comments.  Pursuit of the "All Band Antenna" is the albatross around the neck of many newer hams, and many OMs as well.  The antenna with the least design compromises tend to cover only one band, i.e. a dipole or a (full sized) 1/4 wavelength vertical.   Can either of these antennas operate (present a reasonable VSWR, and thus 'take power') on other bands, i.e. the 3rd harmonic?  Certainly.  But if we don't examine the radiation pattern produced by said 'harmonic operation' then the utility of the antenna remains undefined, beyond the anecdotal declarations that such antennas "work" for that operator at his/her installation. 

Defining your Use Case is foundational to qualifying your results, and yet most hams  - whether they formally develop their antenna requirements at all - don't state what those requirements are.  E.G. NVIS and DX are, essentially, orthogonal propagation modes - an antenna well-suited to one of these modes is almost always a disappointment when examined with regard to it's utility for the other.  The ubiquitous failure by most hams to declare the use case(s) and/or other bounding parameters they are working under, makes antenna design and construction appear more like alchemy than science, but it doesn't have to be that way.