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Re: need a new pc ??

 

omitting the word "new" is more accurate. I have purchased several refurbished Dell box PC's with great success. $300 is a great price to pay for this PC.
Re: End Fed antennas w/ uBITX #ubitx

Gordon Gibby
 

¿ªÔÆÌåÓý

Chuck, Alyson, and others: ?could I get a schematic of your parallel resonant tuning system? And could I get Alyson and or Warren to come yet on what permeability toroid is optimal?

Warren, I¡¯m not bright enough to know if your method of trying to figure out the results of the poor load is correct or not but it seems like a good first cut. ? ?

With a bunch of series/parallel resistors it should be easy to make a 2450 load, one could even do it with surface mount devices and have very little inductance I believe. ? ... ? 40 100,000 ?half watt resistors in parallel would give a really low inductance 20 W load.? ?Cost would probably be five dollars. ?No reason not to give it a try! ?

I dimly understood Alyson¡®s concerns about the back to back system, seems like it wouldn¡¯t be too hard to try it without the connection and with the connection and see if there¡¯s any difference. ?She knows way more than I ever willabout this kind of stuff

I¡¯m trying to see if I can work up the guts to put two of our off-center fed homebrew Balun ?systems back to back and figure out what our losses were! ?I¡¯m not sure I really want to know! ?

Gordon



On Aug 1, 2018, at 10:41, ajparent1/KB1GMX <kb1gmx@...> wrote:

Tim,

I did see that.? I appreciate that but I do have stock here thank you.

Allison

Re: End Fed antennas w/ uBITX #ubitx

 

I don't accept their .2db.? Also their process is only workable if they do the math to back out the?
mismatch loss.

Do I think their procedure is a good way to do it.? No.? Did that do the math to correct their data
for mismatch loss? No I see no mention or statement correcting for that.

If your argument is their test is wrongly done or has a incorrect conclusion then we do agree.

The process and procedures normally used to make that kind of measurement are likely
to disagree with their result and conclusions but will produce an accurate answer when
performed correctly.


Allison
Re: End Fed antennas w/ uBITX #ubitx

 

Tim,

I did see that.? I appreciate that but I do have stock here thank you.

Allison
Re: End Fed antennas w/ uBITX #ubitx

 

Chuck, I haven't yet built two 49:1 (one is not enough for the back to back test hi hi ), but I would use ferrites with permeability close to 800, not the powdered iron toroids like the red and the yellow you have selected (permeability is less than 10). I imagine that the inductance needed at 2500ohm needs to be very high. I might be wrong as I have not made yet one with such a high transformation radio, but I feel I am quite right, IMHO.


Il 01/ago/2018 15:56, "Chuck, N1KGY" <cwayers12@...> ha scritto:
On Wed, Aug 1, 2018 at 09:04 AM, Gordon Gibby wrote:

At any rate, it will be a huge improvement over what most of them had beforehand (NOTHING HF).? ?

I've gone this route also, Gordon.? I bought 4 uBitX units, with the intent that I will have several HF rigs for operating activities such as Field Day, and as HF rigs to loan to new hams.? For both of those use cases, a simple and efficient antenna is needed, and I've chosen to go with EFHWs using parallel-resonant matching units built around T82 toroidal inductors - T82-2 for the 40/30/20 meter units, and T82-6 for the 20/17/15/12/10 meter units.? I used magnet wire and mica compression 'trimmer' caps which I had NOS in my parts collection, so the total cost of each matching unit for me was? ~$10.? The enclosures turn out to be the most expensive part (~$2.75 each).

one year ago these hams?didn't know a resistor from a transistor.....

and that is a real WIN.
Re: experience with Sunil VU3SUA's enclosures #ubitx

 

Mine took about 6 weeks to get to Arizona, but it was worth the wait.? Good looking cabinet.? I agree with others that paint in the openings was heavy, but a little sanding with a Dremel tool took care of that.? Isn't that why you have those fun tools.? You need something to use them on!!? Also, I had to replace the on/off switch, but a trip to my local electronics supply store and $3.00 fixed that.? Besides, I found $40 worth of other stuff that I just couldn't pass up.

Moral of the story, be patient. His case is very well made and the extra parts are useful. I don't have to go looking in the junk box for a knob.?
Re: Spurious RF at beginning of CW transmission in the uBitx

 

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Dexter

On further examination the problem seems more insidious than just the single capacitor in the audio section.? Each bidlrectional amplifier has its owm small capacitor and apparently contributes to the problem.? It now looks like the TX ang RX power feed lines may need some conditioning.

Arv
_-_




Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------
From: Dexter N Muir <dexy@...>
Date: 7/31/18 5:45 PM (GMT-07:00)
Subject: Re: [BITX20] Spurious RF at beginning of CW transmission in the uBitx

So for BITX40 a diode in series with R111 blocks C11 from supplying Q16 as well. Now supply that diode direct from +12, no on/off of U1 and less current through K1 pin 3. R111 can then be either reduced (to 10) or eliminated/shorted.

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

 

¿ªÔÆÌåÓý

BTW:

in the original BITX20 these diodes were in eacht RX and TX path leading to the individual amplifiers.

Henning Weddig

DK5LV


Am 31.07.2018 um 11:25 schrieb n1kw@...:

Hi Arv,

I have not played with the radio much on SSB but suspect that is probably the cause for the "BITX Click". Simply adding a diode in series with R66 (cathode toward C64) should fix the problem.

It is important to note that the possibility of brief oscillation could occur in both the 12 and 45 MHz bidirectional IF amplifier stages because of the back feeding of power from C52 and C64 during RX-TX and TX-RX transitions. Diodes added in series with R52 and R66 should eliminate that possibility. The values of remaining bypass capacitors (0.1 uF) in the IF amplifiers and associated discharge paths should result in extremely short time constants and should not be an issue.

Cheers and 73,
Bob N1KW
Re: Spurious RF at beginning of CW transmission in the uBitx

 

So for BITX40 a diode in series with R111 blocks C11 from supplying Q16 as well. Now supply that diode direct from +12, no on/off of U1 and less current through K1 pin 3. R111 can then be either reduced (to 10) or eliminated/shorted.
Re: End Fed antennas w/ uBITX #ubitx

 

On Wed, Aug 1, 2018 at 09:04 AM, Gordon Gibby wrote:

At any rate, it will be a huge improvement over what most of them had beforehand (NOTHING HF).? ?

I've gone this route also, Gordon.? I bought 4 uBitX units, with the intent that I will have several HF rigs for operating activities such as Field Day, and as HF rigs to loan to new hams.? For both of those use cases, a simple and efficient antenna is needed, and I've chosen to go with EFHWs using parallel-resonant matching units built around T82 toroidal inductors - T82-2 for the 40/30/20 meter units, and T82-6 for the 20/17/15/12/10 meter units.? I used magnet wire and mica compression 'trimmer' caps which I had NOS in my parts collection, so the total cost of each matching unit for me was? ~$10.? The enclosures turn out to be the most expensive part (~$2.75 each).

one year ago these hams?didn't know a resistor from a transistor.....

and that is a real WIN.
Re: End Fed antennas w/ uBITX #ubitx

Warren Allgyer
 

Iz,

According to the email trail the 800 ohm load was selected because that was the maximum the test fixture could produce.?

The 6 dB figure comes from a simulation that I did in my lab. I calibrated the spectrum analyzer/tracking generator combination to 0 with a test cable assembly. I then shunted the S/A input with a 22 ohm resistor, resulting in about a 16 ohm load for the tracking generator. This reduced the displayed power level by 6.5 dB.

What the displayed value on the source RF meter in the test setup would be determined by the output characteristics of the RF source and the probe characteristics of the power meter, neither of which I have access to. I can be assured however that the reading would be wildly inaccurate.

WA8TOD
Re: End Fed antennas w/ uBITX #ubitx

 

We need an update in QST!? Was the 800ohm load selected to test the off-frequency characteristics of the 49:1 transformer? Il the load becomes 16ohm because of the transformer, the mismatch loss should be 2db, why you say over 6db?


Il 01/ago/2018 15:18, "Russ Hines" <russ@...> ha scritto:
Noticing this thread is taking on the epic proportions of a similar thread involving baluns on another forum some years ago.? It resulted in this paper:



Gentleman and lady, write a paper.
Russ Hines
JMS & Associates, Inc.
SBE CSRE
WB8ZCC
--
Reply to: russ@...
On 8/1/2018 9:04 AM, Gordon Gibby wrote:

?Do you know why they didn't use 49*50 ohms as their termination?? ?


I didn't read the email trail (sorry, just not enough time in this world) but it seems like you could make a dummmy load for that if necessary.? ?


What I have gleaned out of all this argumentation back-and-forth is that these things can have single-digit losses if working into a resonant piece of wire.? ?And that using a tuner is preferable. [I always work for lowest losses personally.]? Some of our newer hams locally are very limited in their "radio assets".? ?We'll be building uBitx's beginning in a bout 3 weeks.? We have already built 11 knockoffs of the Buckmaster off-center fed antenna and I hope to high heaven we built baluns etc with single-digit losses!!? ?At any rate, it will be a huge improvement over what most of them had beforehand (NOTHING HF).? ? Their skills are growing and I've learned a lot from all the discussions of various "issues" on this forum.? ?


After we get the "stock units" working, hopefully with v4 factory software and setting the oscillator numbers precisely in the code itself, we will begin on some of the most important improvements, which I haven't had time to get to quite yet....one year ago these hams?didn't know a resistor from a transistor.....


cheers,


gordon



From: [email protected] <[email protected]> on behalf of Warren Allgyer <allgyer@...>
Sent: Wednesday, August 1, 2018 8:53 AM
To: [email protected]
Subject: Re: [BITX20] End Fed antennas w/ uBITX
?

I have been asked by private message what it is about the QST Review test methodology that I found invalid. I constructed this explanation of their test in response and I would like to share it with the group.

The testers used a setup that is used by the ARRL Lab to test the loss of Antenna Tuners. When testing an Antenna Tuner the tuner itself converts whatever load is presented by the "Load Box" back to 50 ohms as a termination for the RF Source. The inline HP RF Power Meter is working in its natural 50 ohm domain and should be accurate within the specification of the meter.

When testing a 49:1 transformer however, there is no way to adjust the termination to 50 ohms. So, with an 800 ohm load selected in the load box as the authors specify in the email trail, the RF Source and the source power meter are operating in a 16 ohm environment. What the actual power out of the source is, and what power is indicated on the source power meter with a 16 ohm load, are determined by the characteristics of each box. It most certainly cannot be assumed to be 10 watts. The error in this step can easily be over 6 dB.

When the test therefore shows the transformer to have a loss of 0.2 dB, the actual loss could be as much as 6.2 dB.

The two transformer back to back test that I have documented does not suffer from a load mis-match and is therefore a far more appropriate way to do this measurement.
Re: End Fed antennas w/ uBITX #ubitx

Warren Allgyer
 

Gordon, your summary is spot on.

The appropriate termination value for the 49:1 transformer would be 2450 ohms in order to present a 50 ohm load to the source. The load box used in the ARRL lab would only go as high as 800 ohms. So, in addition to the inaccuracy caused by the mis-termination of the RF Source, the transformer was also operating at a mismatch of 3:1, which would introduce an additional distortion of the results.

WA8TOD
Re: SI5351 quadrature VFO

 

Hello Miguel,
I have seen the video on you tube and you have done a remarkable job.
I am unable to find the sketch on the above link
Can you please share the link to me on my email VU3RQX@...

73

VU3RQX
Re: End Fed antennas w/ uBITX #ubitx

 

¿ªÔÆÌåÓý

Noticing this thread is taking on the epic proportions of a similar thread involving baluns on another forum some years ago.? It resulted in this paper:



Gentleman and lady, write a paper.
Russ Hines
JMS & Associates, Inc.
SBE CSRE
WB8ZCC
--
Reply to: russ@...
On 8/1/2018 9:04 AM, Gordon Gibby wrote:

?Do you know why they didn't use 49*50 ohms as their termination?? ?


I didn't read the email trail (sorry, just not enough time in this world) but it seems like you could make a dummmy load for that if necessary.? ?


What I have gleaned out of all this argumentation back-and-forth is that these things can have single-digit losses if working into a resonant piece of wire.? ?And that using a tuner is preferable. [I always work for lowest losses personally.]? Some of our newer hams locally are very limited in their "radio assets".? ?We'll be building uBitx's beginning in a bout 3 weeks.? We have already built 11 knockoffs of the Buckmaster off-center fed antenna and I hope to high heaven we built baluns etc with single-digit losses!!? ?At any rate, it will be a huge improvement over what most of them had beforehand (NOTHING HF).? ? Their skills are growing and I've learned a lot from all the discussions of various "issues" on this forum.? ?


After we get the "stock units" working, hopefully with v4 factory software and setting the oscillator numbers precisely in the code itself, we will begin on some of the most important improvements, which I haven't had time to get to quite yet....one year ago these hams?didn't know a resistor from a transistor.....


cheers,


gordon



From: [email protected] <[email protected]> on behalf of Warren Allgyer <allgyer@...>
Sent: Wednesday, August 1, 2018 8:53 AM
To: [email protected]
Subject: Re: [BITX20] End Fed antennas w/ uBITX
?

I have been asked by private message what it is about the QST Review test methodology that I found invalid. I constructed this explanation of their test in response and I would like to share it with the group.

The testers used a setup that is used by the ARRL Lab to test the loss of Antenna Tuners. When testing an Antenna Tuner the tuner itself converts whatever load is presented by the "Load Box" back to 50 ohms as a termination for the RF Source. The inline HP RF Power Meter is working in its natural 50 ohm domain and should be accurate within the specification of the meter.

When testing a 49:1 transformer however, there is no way to adjust the termination to 50 ohms. So, with an 800 ohm load selected in the load box as the authors specify in the email trail, the RF Source and the source power meter are operating in a 16 ohm environment. What the actual power out of the source is, and what power is indicated on the source power meter with a 16 ohm load, are determined by the characteristics of each box. It most certainly cannot be assumed to be 10 watts. The error in this step can easily be over 6 dB.

When the test therefore shows the transformer to have a loss of 0.2 dB, the actual loss could be as much as 6.2 dB.

The two transformer back to back test that I have documented does not suffer from a load mis-match and is therefore a far more appropriate way to do this measurement.
Re: End Fed antennas w/ uBITX #ubitx

Gordon Gibby
 

¿ªÔÆÌåÓý

?Do you know why they didn't use 49*50 ohms as their termination?? ?


I didn't read the email trail (sorry, just not enough time in this world) but it seems like you could make a dummmy load for that if necessary.? ?


What I have gleaned out of all this argumentation back-and-forth is that these things can have single-digit losses if working into a resonant piece of wire.? ?And that using a tuner is preferable. [I always work for lowest losses personally.]? Some of our newer hams locally are very limited in their "radio assets".? ?We'll be building uBitx's beginning in a bout 3 weeks.? We have already built 11 knockoffs of the Buckmaster off-center fed antenna and I hope to high heaven we built baluns etc with single-digit losses!!? ?At any rate, it will be a huge improvement over what most of them had beforehand (NOTHING HF).? ? Their skills are growing and I've learned a lot from all the discussions of various "issues" on this forum.? ?


After we get the "stock units" working, hopefully with v4 factory software and setting the oscillator numbers precisely in the code itself, we will begin on some of the most important improvements, which I haven't had time to get to quite yet....one year ago these hams?didn't know a resistor from a transistor.....


cheers,


gordon



From: [email protected] <[email protected]> on behalf of Warren Allgyer <allgyer@...>
Sent: Wednesday, August 1, 2018 8:53 AM
To: [email protected]
Subject: Re: [BITX20] End Fed antennas w/ uBITX
?

I have been asked by private message what it is about the QST Review test methodology that I found invalid. I constructed this explanation of their test in response and I would like to share it with the group.

The testers used a setup that is used by the ARRL Lab to test the loss of Antenna Tuners. When testing an Antenna Tuner the tuner itself converts whatever load is presented by the "Load Box" back to 50 ohms as a termination for the RF Source. The inline HP RF Power Meter is working in its natural 50 ohm domain and should be accurate within the specification of the meter.

When testing a 49:1 transformer however, there is no way to adjust the termination to 50 ohms. So, with an 800 ohm load selected in the load box as the authors specify in the email trail, the RF Source and the source power meter are operating in a 16 ohm environment. What the actual power out of the source is, and what power is indicated on the source power meter with a 16 ohm load, are determined by the characteristics of each box. It most certainly cannot be assumed to be 10 watts. The error in this step can easily be over 6 dB.

When the test therefore shows the transformer to have a loss of 0.2 dB, the actual loss could be as much as 6.2 dB.

The two transformer back to back test that I have documented does not suffer from a load mis-match and is therefore a far more appropriate way to do this measurement.
Re: End Fed antennas w/ uBITX #ubitx

Warren Allgyer
 

I have been asked by private message what it is about the QST Review test methodology that I found invalid. I constructed this explanation of their test in response and I would like to share it with the group.

The testers used a setup that is used by the ARRL Lab to test the loss of Antenna Tuners. When testing an Antenna Tuner the tuner itself converts whatever load is presented by the "Load Box" back to 50 ohms as a termination for the RF Source. The inline HP RF Power Meter is working in its natural 50 ohm domain and should be accurate within the specification of the meter.

When testing a 49:1 transformer however, there is no way to adjust the termination to 50 ohms. So, with an 800 ohm load selected in the load box as the authors specify in the email trail, the RF Source and the source power meter are operating in a 16 ohm environment. What the actual power out of the source is, and what power is indicated on the source power meter with a 16 ohm load, are determined by the characteristics of each box. It most certainly cannot be assumed to be 10 watts. The error in this step can easily be over 6 dB.

When the test therefore shows the transformer to have a loss of 0.2 dB, the actual loss could be as much as 6.2 dB.

The two transformer back to back test that I have documented does not suffer from a load mis-match and is therefore a far more appropriate way to do this measurement.

QST Test Methodology.pdf
QST Test Methodology.pdf

New uBITX Raduinos for sale #ubitx

 

I have 2 brand new, unused Raduinos from V4 kits of mine that I will never use.? These are the later Raduinos that have the NANO mounted on the backside to keep it from interfering with the display.

They are still wrapped in the original bubble wrap and will include the original display. They are available for $40 each shipped in the US.? International shipping costs $14 to $15 USD and would have to be added for shipping to anyone outside the US.

Interested,? please reply direct to me, not the group to minimize clutter (there's been too much of that lately).? My email address is good on my website (www.w0eb.com) there are links there to email me but it is (use standard email format) w0eb [at] cox dot net.

Jim Sheldon, W0EB
Re: Anyone with a Raduino for the uBITX version3 for sale?

 

Hi, Dennis,

Do you have a link for the VF4PLN board?

73,

Paul K2AYZ
Re: Spurious RF at beginning of CW transmission in the uBitx

 

This issue of carrier leak on PTT caused by DC flow through the product detector
seems to be absent in uBitx.

Raj

At 31-07-18, you wrote:

Raj had a nice simple fix for the carrier burst on the Bitx40,
might be applicable to the uBitx:?
??? /g/BITX20/message/33707
??? /g/BITX20/message/33742

As I recall, there were a half dozen other fixes that worked.
We've already mentioned delays in software as Allard has done for the Bitx40.
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