Date   

Opposite side band rejection ubitx V6

barry halterman
 

May I ask what  the opposite side band rejection typically is on the ubitx? Does 35db seem about right?
Barry
K3bo


Re: FS V6

John Veach <ke4d@...>
 

Sold. 


Re: RFI on 2 meters from uBitx

Evan Hand
 

I checked, and I do have the 2 meter signal of the SI5351 3rd harmonic.  It goes away on CW TX, confirming to me it is the LO Clock2 signal, as that is changed to the actual frequency on CW TX.

As Jay noted, it is quite strong.  My ubitx v4 has the relays replaced, and I have verified the harmonic reduction after the replacement.  It is in a metal case, however, I do not have a good ground in the shack, just a copper water pipe. If I use my hand as a temporary RF choke around the antenna coax, I can get a significant reduction in the signal strength on the Kenwood TM-D710G, the squelch will drop out.  Based on my simple test, ferrites on all lines into and out of the rig would be the answer.

Best guesses at this point.
73
Evan
AC9TU


Re: ANTUINO antenna analzer CERTAIN CLARIFICATIONS REG

R. Tyson
 

In response to the original post....

Calculating the length of a dipole from the formula is the first stage and gives you an approximate length. It is best to cut the dipole longer than the calculated length and then trim a bit off each end until you get it to resonance.

As others have mentioned, the antenna will be affected by it's suroundings and also any bending out of shape that may be done to get it to fit into the space available.

Mounting the dipole as an inverted  V  will also affect the resonant length and the feed point impedance. The height of the antenna above ground also affects these things.

So you have it up as a inverted  V  fan dipole which appears to be cut too short to resonate where you want it. Pity as it is easier to cut bits off than to add bits to lengthen them.

You need to add wire, allow extra so you can trim it back, you don't want to keep soldering extra bits on. Do this with both the 40 and 20 metre sections ( I think that's what you originally cut it for). As it's a fan dipole start with the longest, 40M, part and slowly trim each end back until your NanoVNA shows you have it resonant where you want it to be.
Once you have the longest section trimmed then do the same with the shorter 20 metre section. There will be some interaction between the 2 fan dipoles and you should trim the longest one and only then trim the shorter one. Then check where the resonance is on both bands again.... you may need some more slight trimming due to their interaction but
chances are it may be O.K. and the job's done.

If you check the SWR it should be below 2:1, it will probably be lower but it would be O.K at that level. 1:1 SWR is very nice but anything below 2:1 will get you on the air.

Reg                        G4NFR


Re: RFI on 2 meters from uBitx

Dale Parfitt
 

Hi Evan,

While there can be a good deal of math involved to optimize ferrite common mode choking impedance, it  so easy to do trial and error that for most cases we can forgo the math.

I had  a serious distortion issue when I was connecting my Drake TR-7 to my solid state SPE Expert HF amplifier. My K3 had always played beautifully with the SPE as had  a number of other boatanchor rigs- both vacuum tube and solid state. I tried ALC, no ALC, all sorts of fixes. The issue turned out to be common mode on the PTT line from the rig to the amplifier. Who would have thunk it.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:45 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI on 2 meters from uBitx

 

Dale's message prompted me to think of other cables that run near the Raduino.  By chance are you using CAT from the rig?   Snap a ferrite on it and any digital mode cables. 

Dale,
A good suggestion for the ferrites.  I already have them on my rigs because of RF feedback.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Evan Hand
 

Dale's message prompted me to think of other cables that run near the Raduino.  By chance are you using CAT from the rig?   Snap a ferrite on it and any digital mode cables. 

Dale,
A good suggestion for the ferrites.  I already have them on my rigs because of RF feedback.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Dale Parfitt
 

Regarding the 2M issue, you might also try disconnecting your HF antenna and see if the issue goes away. If it does, then some #43 snap on ferrites right where the antenna coax exits the BitX should help- same for the key, mic and power leads. Of course, if the rig is not in a metal cabinet then all bets are off.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI on 2 meters from uBitx

 

Jay,
Ensuring that it is installed in a metal case that is grounded is the only thing that I could see helping.  Are there any modifications installed?

What you are seeing is the 3rd harmonic of the Clock2 out of the SI5351 that is used in the first mixer to convert the incoming RF to the 45 MHz IF frequency.  That is not a mixing product.  It is the local oscillator for the conversion to 45 MHz IF.  Those signal traces are fairly short, so not much of an antenna.  Also, since it is on both transmit and receive, I doubt that the first mixer is damaged. 

I will see if one of my ubitx has the same issue.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Evan Hand
 

Ashhar Farhan and Raj,

The original email stated that it was there on both transmit and receive.  I think that should rule out the relays, any of the transmitter amplifier stages, and the antenna match.  I guess it is possible that a bad match could affect the 30 Mhz LPF at the input to the first IF,  Still, the double-balanced mixer should isolate the LO from the RF port.

Am I missing something?
73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Ashhar Farhan
 

It could be lack of shielding on the two meter rig too. We have swept the output of ubitx, there are very very small spurs at 2 meters. Indeed, it would be a wonderful surprise to find the venerable IRF510 shaking a leg on 144 mhz.
I hope 80 meter antenna is well matched.

On Thu 18 Jun, 2020, 5:41 PM Raj vu2zap, <rajendrakumargg@...> wrote:
You could try replacing relays KT1/2/3 with Axicom RF relays, that should reduce this.
Check earlier posts for details.

Raj

At 18/06/2020, you wrote:
>I have been experiencing RFI on the 2 meter band when my V3 is tuned to the upper end of 75 meters. I had my uBitx tuned to the TN Phone net at 3.980 MHz and my 2 meter rig tuned to my local repeater at 146.91 MHz. The 2 meter rig showed full scale receive, with no audio. I checked with my hand held and it was full scale at least 50 feet from the uBitx. The RFI exists when the uBitx is in RX as well as TX. Seems like a 3rd harmonic of a mixing product; (45 MHz+3.98 MHz) X 3 = 146.94 MHz
>
>Any ideas where or how to add shielding or if a component needs to be replaced?
>
>Thanks,
>Jay
>WS4JM





Re: RFI on 2 meters from uBitx

Evan Hand
 

Jay,
Ensuring that it is installed in a metal case that is grounded is the only thing that I could see helping.  Are there any modifications installed?

What you are seeing is the 3rd harmonic of the Clock2 out of the SI5351 that is used in the first mixer to convert the incoming RF to the 45 MHz IF frequency.  That is not a mixing product.  It is the local oscillator for the conversion to 45 MHz IF.  Those signal traces are fairly short, so not much of an antenna.  Also, since it is on both transmit and receive, I doubt that the first mixer is damaged. 

I will see if one of my ubitx has the same issue.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

 

You could try replacing relays KT1/2/3 with Axicom RF relays, that should reduce this.
Check earlier posts for details.

Raj

At 18/06/2020, you wrote:
I have been experiencing RFI on the 2 meter band when my V3 is tuned to the upper end of 75 meters. I had my uBitx tuned to the TN Phone net at 3.980 MHz and my 2 meter rig tuned to my local repeater at 146.91 MHz. The 2 meter rig showed full scale receive, with no audio. I checked with my hand held and it was full scale at least 50 feet from the uBitx. The RFI exists when the uBitx is in RX as well as TX. Seems like a 3rd harmonic of a mixing product; (45 MHz+3.98 MHz) X 3 = 146.94 MHz

Any ideas where or how to add shielding or if a component needs to be replaced?

Thanks,
Jay
WS4JM


RFI on 2 meters from uBitx

Jay - WS4JM
 

I have been experiencing RFI on the 2 meter band when my V3 is tuned to the upper end of 75 meters. I had my uBitx tuned to the TN Phone net at 3.980 MHz and my 2 meter rig tuned to my local repeater at 146.91 MHz. The 2 meter rig showed full scale receive, with no audio. I checked with my hand held and it was full scale at least 50 feet from the uBitx. The RFI exists when the uBitx is in RX as well as TX. Seems like a 3rd harmonic of a mixing product; (45 MHz+3.98 MHz) X 3 = 146.94 MHz

Any ideas where or how to add shielding or if a component needs to be replaced?

Thanks,
Jay
WS4JM


Re: ANTUINO antenna analzer CERTAIN CLARIFICATIONS REG

 

For proper SWR readings your dipole must have a 1:1 Balun at the feed point.

The resonant length you have calculated is for plain metal (copper) wire.
Wire coated with plastic will not have the calculated length resonance.

My 40M dipole which intentionally uses plasic insulated wire is 28' on
either side. I could not accommodate 33ft..

Raj


At 17/06/2020, you wrote:

HI GOOD DAY TO ALL.

    I recently purchased an ANTUNINO Antenna Analyser.

   I used it to measure the SWR of my antenna system. I erected an inverted VEE antenna system  for  40 m and 20 m bands with a common single coaxial feeder. When  I measured the SWR , the ANTUINO shows the following values.

At    7.007MHZ     SWR is 1.9

At   14.554 MHZ  SWR is 1.8

     Subsequently using the plot function of the ANTUNINO I  measured  the frequencies at which  SWRs are lowest  and the values are as below.

At  15.822MHZ  SWR      is  1.0

At   8.600 MHZ   SWR    is  1.10

At   11.900 MHZ   SWR   is 1.10.

  As such  I cannot understand when the antenna system  has been installed with calculated resonant lengths of arms corresponding to  7 MHZ and 14 MHZ bands, the SWRs are low on some other irrelevant frequencies.  Is there any error /mistake in my observation.?

   . I appreciate, any one, kindly through some light on the above and give some tips on adjusting the system to achieve minimum SWRs in 7 and 14 MHZ (preferably on 7075 MHZ and 14.175 MHZ.

   Thanks a lot in advance

                                                                          With 73

                                                                           MUTHU 

                                                                           VU2LMN

                                                                         +919443114779


Re: bitx v6 is here

 

It helps if you leave commented part of post that you are referring to.

I think you are referring to QST, all magazines I have subscription to are
only available in PDF and not print currently.

Raj

At 17/06/2020, you wrote:
Over the last few months I've been searching for this title to no avail. Has the publication been canceled?


Re: ANTUINO antenna analzer CERTAIN CLARIFICATIONS REG

 

Hi Laksh,

The formula is not meant to be perfect - it only gives approximations.  If we all lived in outerspace, with nothing near our antennas, use of a formula could be quite reliable, however our antennas are near many objects which affect resonance and the value of R at resonance. 

A dipole at resonance and fed in the middle, has final value of R between about 50-100 ohm depending on height above the ground.

Resonance also change with height above ground -- the closer to ground, the more the antenna needs to be shortened.

Other metal objects nearby affect these too.

Since you have a fan dipole I think, then how close the two wires are to eachother can make a difference and aslo might lead to strange resonances.

The coax lead needs to be brought out midway between the arms -- if it gets near to one side or the other then the coax shield is more likely to become part of the antenna.

73,

Mark


Re: Nextion Display on uBITX #ubitx #nextion

rpremooak@...
 

Which board number are you using for the 2.8" display,

I am using NX3224k0028_011 I have tried multiple .TFT which all say they are incompatible.  Anyone know of another option.  I pulled them from

v1.092 – 3.5″ Enhanced
https://ubitx.net/download/3-5%e2%80%b3-enhanced-nextion-screen-files-tft-for-loading-on-micro-sd-kn4ud/

I tried the basic and the enhanced file and even went up to the 3.5" file


Re: selling my V6

Bob Lunsford
 

Thanks for letting me know.

It did work but from the other VU-ham's video, I thought it had to be tuned. Now I learn too late that I should have left it alone.

I used WWV at 10 and 5 MHz ans then used WTAM at 1100 KHz as reference signals to zero beat. Got it very close but now I have the same signal on USB as on LSB. I'm giving up.

I even tried the locate screen in the menu but still same sig on USB as on LSB.

I no longer have as much patience as I had when younger. Maybe it will be a good deal for someone with more patience.

Bob — KK5R
nocrud222@...

On Wednesday, June 17, 2020, 3:58:16 PM EDT, Ashhar Farhan <farhanbox@...> wrote:


The BFO is pretuned from the factory. you don't HAVE to do it. This is a myth. It works out of the box for almost everyone. Many think that they need to do it and they mess it up. It will take you about 20 minutes to assemble it. Try it on air before giving it up.
- Farhan

On Thu, Jun 18, 2020 at 1:11 AM Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:
I am selling my full kit V6. I do not have a way tyo do the BFO tuning, etc. Included will be the V6, microphone, complete kit box, etc. (all items I received with the kit).

It is nice and receives OK but the tune-up is what I cannot do. Wish it could be done but I do not have Cromium or a computer that will do the microphone to HF Sigs thing.

It will be sold for $200 stateside. If anyone is interested, email me at:


Bob — KK5R


Re: selling my V6

Ashhar Farhan
 

The BFO is pretuned from the factory. you don't HAVE to do it. This is a myth. It works out of the box for almost everyone. Many think that they need to do it and they mess it up. It will take you about 20 minutes to assemble it. Try it on air before giving it up.
- Farhan

On Thu, Jun 18, 2020 at 1:11 AM Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> wrote:
I am selling my full kit V6. I do not have a way tyo do the BFO tuning, etc. Included will be the V6, microphone, complete kit box, etc. (all items I received with the kit).

It is nice and receives OK but the tune-up is what I cannot do. Wish it could be done but I do not have Cromium or a computer that will do the microphone to HF Sigs thing.

It will be sold for $200 stateside. If anyone is interested, email me at:


Bob — KK5R


Re: selling my V6

Bob Lunsford
 

I am selling my full kit V6. I do not have a way tyo do the BFO tuning, etc. Included will be the V6, microphone, complete kit box, etc. (all items I received with the kit).

It is nice and receives OK but the tune-up is what I cannot do. Wish it could be done but I do not have Cromium or a computer that will do the microphone to HF Sigs thing.

It will be sold for $200 stateside. If anyone is interested, email me at:

nocrud222@...

Bob — KK5R


5 & 12 VDC cooling fans for the V6 in particular. From past experience with these fans I have found that they can be a little noisy when moving air over a closely mounted surface. To quiet these things down I install a silicon rectifier diode in series with one of the leads The approx. .7v drop will usually slow it down so that it'l be less annoying.

JJ Kowal <arsk0wal@...>