Date   
Re: ubitx raduino issue/AKA the radio doesn't receive

Gordon Gibby
 

you can use any waterfall (e.g. FLDGI, or even packet sound card software) to do the same.


On Tue, Nov 12, 2019 at 2:45 PM Evan Hand <elhandjr@...> wrote:
zl1rd,

Most likely the problem is the BFO adjustment.  We would need more information on which model and what equipment you would have for testing.

I personally have found a free Audio Spectrum Analyzer (google one on the net) was the most helpful.  You can plug in a usb mic, have it close to the speaker of the uBitx, tune to a clear frequency, and adjust the BFO for the noise plateau to be centered between 500 and 3,000 hz.  The BFO has the most impact on the receive sensitivity.

There are other methods on groups.io.  You can search for them with BFO Setting or something simalar, just remember that the v3 and v4 are at a different frequency than the v5.

Hope that helps,
Evan
AC9TU
 

Re: ubitx raduino issue/AKA the radio doesn't receive

Evan Hand
 

zl1rd,

Most likely the problem is the BFO adjustment.  We would need more information on which model and what equipment you would have for testing.

I personally have found a free Audio Spectrum Analyzer (google one on the net) was the most helpful.  You can plug in a usb mic, have it close to the speaker of the uBitx, tune to a clear frequency, and adjust the BFO for the noise plateau to be centered between 500 and 3,000 hz.  The BFO has the most impact on the receive sensitivity.

There are other methods on groups.io.  You can search for them with BFO Setting or something simalar, just remember that the v3 and v4 are at a different frequency than the v5.

Hope that helps,
Evan
AC9TU
 

Re: ubitx raduino issue/AKA the radio doesn't receive

zl1rd@...
 

Hi John

Wonder if you have solved this problem?  I just finished my uBITX and experience the same issues you have....  receiver sensitivity very low etc.  Would you mind responding to zl1rd@... and let me know about the progress you have made.  Your help is much appreciated.

Regards,


Rob
zl1rd

Re: S meter locking up

howard winwood G4GPF
 

It caught me out too, audio not good, AGC not good so decided to trace wiring. What a difference it makes!!!!

G4GPF

On Mon, 11 Nov 2019, 23:21 Philip, <philip.g7jur@...> wrote:
That clever person could been me.
I see that the latest drawing is still wrong, This error has a long history.

Philip G7JUR

Re: S meter locking up

Maurice Bersan
 

Yes, the brown wire is actually v high and black is v medium.

On 12 Nov 2019 10:15 a.m., Justin Phillips K5AXL <dolmdemon@...> wrote:
I'm confused, are you talking about the connection from the volume jack on the front panel board supplied by inkits? The brown and black wires are reversed?

Re: S meter locking up

Justin Phillips K5AXL
 

I'm confused, are you talking about the connection from the volume jack on the front panel board supplied by inkits? The brown and black wires are reversed?

Re: S meter locking up

Maurice Bersan
 

Yes, however the wire colour changed with the extra board.
Apologies for miss spelling your name on my earlier post.
Thanks again Philip.

Re: S meter locking up

Maurice Bersan
 

Well thanks Phillip, wiring it up correctly made a big difference to the ALC operation....
Cheers
Maurice

On 12 Nov 2019 7:15 a.m., Philip <philip.g7jur@...> wrote:
That clever person could been me.
I see that the latest drawing is still wrong, This error has a long history.

Philip G7JUR

Re: S meter locking up

Justin Phillips K5AXL
 

Could this be why my audio amp squeels when I turn the preset pot more than 1/16th up from off? 


On Mon, Nov 11, 2019, 5:39 PM Philip <philip.g7jur@...> wrote:
Here is my posting from last year

The wire up drawing has an error regarding the volume control connections. It shows the orange wire as being Vol_high. And the yellow wire as being Vol_mid, going to the wiper.
The orange wire is in fact the Vol_mid, and should go to the wiper. And yellow to the hot end.
The pictures are correct.

Philip G7JUR

Re: Are these output watt rating crazy?

 

Oh,

There's not much to do wrong, it's all up to the software!  But this program always seems to agree with the Elsie program by Tonne Software, so I think it's OK.  The values I am taking are from the v3 schematic -- I think the filters are still the same although arranged differently now.  I thought lots of people would have run these through a simulator program already; especially when investigating power variations it could be interesting to get some confirmation of the cutoffs and input impedances.

Cheers,


Mark.

Re: S meter locking up

Philip
 

Here is my posting from last year

The wire up drawing has an error regarding the volume control connections. It shows the orange wire as being Vol_high. And the yellow wire as being Vol_mid, going to the wiper.
The orange wire is in fact the Vol_mid, and should go to the wiper. And yellow to the hot end.
The pictures are correct.

Philip G7JUR

Re: Are these output watt rating crazy?

Jerry Gaffke
 

Mark,

That gives me confidence in how you are simulating these LPF's.
Could be that the 80m LPF really does have a corner at 7mhz.
Or could be that the boards are not being built exactly as described by the v5 schematic.

Jerry


On Mon, Nov 11, 2019 at 12:56 PM, Mark - N7EKU wrote:
It looks like a good filter for 30m and 40m.  Input impedance showed 50 ohms on 30m and 40 ohms on 40m.

Re: S meter locking up

Philip
 

That clever person could been me.
I see that the latest drawing is still wrong, This error has a long history.

Philip G7JUR

Re: Are these output watt rating crazy?

Jerry Gaffke
 

You folks might not have access to the flash drive on my chromebook.
Here's a better place to look for the v5 uBitx schematic:
    https://github.com/afarhan/ubitx_v5/blob/master/ubitx_v5.pdf

Jerry


On Mon, Nov 11, 2019 at 09:07 AM, Jerry Gaffke wrote:
The v5 uBitx wires up the relays much differently to avoid having harmonics leak around the relays.
    file:///home/chronos/u-ba688dba5e13d507cb8c8d472169a2b5e212d72b/MyFiles/Downloads/ubitx_v5.pdf

Re: Are these output watt rating crazy?

 

Hi Jerry,

Thank you for the information on the code.  Here is a simulation of the 750nH filter:



It looks like a good filter for 30m and 40m.  Input impedance showed 50 ohms on 30m and 40 ohms on 40m.

Sorry the image isn't bigger -- in linux the filter program only prints to either a printer or to "Microsoft XPS Document Printer" which I don't have going in linux so I have to do a screenshot.

Cheers,


Mark.

FLDIGI setup

John Faivre
 

I use omnirig with com3 to communicate with WSJTx but I cannot get Hamlib to connect
--
John Faivre WA9SGD

Re: Are these output watt rating crazy?

Bill Cromwell
 

Hi,

I haven't had any luck on 160 meters so far due to a compromised antenna. But rest assured that I am using and external low pass filter that starts to rolloff a little above 2 MHz. The filters inside the radio are definitely *not* for 160 meters.

It hears pretty well on 160 for all I can tell:)

73,

Bill KU8H

On 11/11/19 12:07 PM, Jerry Gaffke via Groups.Io wrote:
---snip-----
However, the stock uBitx definitely does not have a low pass filter appropriate for 160m !!!!!
We've had a number of folks here who assumed it did, since the firmware allowed them to spin down and transmit on 1.8mhz.
The third harmonic of 1.8mhz at 5.4mhz will go out on the air almost as strong as the fundamental.

--
bark less - wag more

Re: Are these output watt rating crazy?

Jerry Gaffke
 

Mark,

Interesting.   

You might be right that the filter with the 900nH inductors has an incorrectly implemented corner frequency.
Worth exploring further.
Your simulation shows a corner at around 7mhz, not the expected 5mhz.
That would let a 3.5mhz second harmonic leak by.
The second harmonic will be quite weak due to the push-pull topology of the IRF510 finals,
this 7mhz corner may not matter.

However, the stock uBitx definitely does not have a low pass filter appropriate for 160m !!!!!
We've had a number of folks here who assumed it did, since the firmware allowed them to spin down and transmit on 1.8mhz.
The third harmonic of 1.8mhz at 5.4mhz will go out on the air almost as strong as the fundamental.

The filter with the 900nH inductors that you simulated is definitely the lowest LPF on the uBitx.
When I said it had a 5mhz corner, I was going by Farhan's circuit description notes.
I had assumed this had been gone over thoroughly, since lots of folks in the forum
were trying to figure out how to reduce the problematic v3 harmonics from leaking past the relays.

I don't think the apparent 7mhz corner you found has anything to do with lack of power on 40m as seen by some.
I think it is more likely that some of the uBitx boards have incorrectly wound 750nH inductors.
When operating on 40m, both the v3 and v5 versions of the uBitx are using the LPF with the 750nH inductors.
At least, when operating with Farhan's code as archived on github.
There are other firmware releases out there, but I suspect they mostly copied
the code to control the LPF relays from Farhan.



Here's the v3 schematic:
  https://github.com/afarhan/ubitx/blob/master/ubitxv3.pdf

And here's the v3 code from
  https://github.com/afarhan/ubitx/blob/master/ubitx_20/ubitx_20.ino
that switches the relays around to select an appropriate LPF:

void setTXFilters(unsigned long freq){

  if (freq > 21000000L){  // the default filter is with 35 MHz cut-off
    digitalWrite(TX_LPF_A, 0);
    digitalWrite(TX_LPF_B, 0);
    digitalWrite(TX_LPF_C, 0);
  }
  else if (freq >= 14000000L){ //thrown the KT1 relay on, the 30 MHz LPF is bypassed and the 14-18 MHz LPF is allowd to go through
    digitalWrite(TX_LPF_A, 1);
    digitalWrite(TX_LPF_B, 0);
    digitalWrite(TX_LPF_C, 0);
  }
  else if (freq > 7000000L){
    digitalWrite(TX_LPF_A, 1);
    digitalWrite(TX_LPF_B, 1);
    digitalWrite(TX_LPF_C, 0);
  }
  else {
    digitalWrite(TX_LPF_A, 1);
    digitalWrite(TX_LPF_B, 1);
    digitalWrite(TX_LPF_C, 1);
  }
}
 
So when operating on 40m (unless you are tuned to be exactly on the lower band edge, don't do that!),
the signals A,B,C  (driving the KT1,KT2,KT3 relays) are driven with 1,1,0 respectively.
KT1 and KT2 are in bypass mode (relay on), and KT3 (off) selects the 7mhz LPF (has 750nH inductors).
So no, on a v3 uBitx, the LPF with the 900nH inductors is only used when operating below (or exactly on) 7mhz.

The v5 uBitx wires up the relays much differently to avoid having harmonics leak around the relays.
    file:///home/chronos/u-ba688dba5e13d507cb8c8d472169a2b5e212d72b/MyFiles/Downloads/ubitx_v5.pdf
The code for v5
    https://github.com/afarhan/ubitx_v5/blob/master/ubitx_v5.1_code.ino
drives the LPF relays with A,B,C == 0,1,0  when operating in the 40m band:

  else if (freq > 7000000L){
    digitalWrite(TX_LPF_A, 0);
    digitalWrite(TX_LPF_B, 1);
    digitalWrite(TX_LPF_C, 0);
  }
This powers the middle relay on the v5 to select the filter with the 750nH inductors,
the other two relays are left unpowered in bypass mode.
Note that the highest freq LPF with the 330nH inductors (for 15m,12m,10m) is always inline on the v5.

Jerry, KE7ER




On Sun, Nov 10, 2019 at 09:08 PM, Mark - N7EKU wrote:
I used the AADE filter simulation/design program.  I posted because I had seem some comments on the power outputs and was curious to simulate the low filter to see if that might impact some of the power levels.  I simulated the lowest filter I saw on the ubitx v3 schematic.  Did I miss a lower one?  This one seems to be the lowest and used for both 40m and 80m with a cutoff very close to 7MHz (actually showed -2dB at 7.3MHz).

Re: S meter locking up

Maurice Bersan
 

SOLVED
I just saw a post by a clever person who discovered a wiring error in the wiring diagram.
I am using one of those universal case kits by inkits with the extra front mounted circuit board for Ptt, audio and CW.
The volume high wire that goes to the volume pot is not the black wire, it's the brown one. The connections diagram appears to be incorrect. I have swapped the two wires and the problem is fixed. I think the post was on Facebook but I can't find it again, so whoever that clever person is, thankyou!
Maurice
Vk6hly

S meter locking up

Maurice Bersan
 

I have just installed a nextion 2.8 screen to my ubitx v5 and I noticed when I tap the screen to select, the s meter shoots up to s8 and sticks there until I either reboot or speak loudly into the mike. I have tried both TFT files with and without s meter but still the same fault. No problems with the old 2 line display screen. I have the kit projects ALC board fitted which works fine with the 2 line display.
Any ideas folks?
Maurice
Vk6hly