Date   
Re: RFI from uBitx TX after AGC and other mods installed

alans77@...
 

Can anyone specify (photo of location needed) a relay contact that is open on transmit and grounded on receive?

73,
Alan N4AYE

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

No photo but that would be K1, the relay that sits over at the left by itself. Underneath you will see one of the contacts is grounded. That's the normally open contact. The next contact down will be the normally closed contact that goes to the bandpass filter. The next contact in that line is the common one that goes to the receive line. Sorry, but my version 3 board is in a difficult case to extract from.
-Don

Re: RFI from uBitx TX after AGC and other mods installed

RowlandA
 

I don't have a separate power source for the PA - I assume to test this I'll have to cut one of the three wires going to the plug into the PCB?  I'll try it Wednesday if it will help with troubleshooting.

Thanks,
Rowland

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

I was looking for an easy test. Lifting the brown wire from the power switch sounded like it might be simple but hold off while I try to think of something else. -Don

Re: Understanding Spurious Emissions

Ashhar Farhan
 

Allison,
What is the exact math of the spur? We can swap the two local oscillators around in software. That is,  the local oscillator can be injected on the other side. Would that help?
- f

On Tue, 26 Jun 2018, 03:09 ajparent1/KB1GMX, <kb1gmx@...> wrote:
On Fri, Jun 22, 2018 at 10:38 pm, Ashhar Farhan wrote:
It may be improper level of LO injection. On the transmit side, the mixer has _very_ strong input termination and LO termination. It will be interesting to study this. Mixers can provide endless amount of fascination or frustration depending on which side of the RF probe you are.
 
Yes they are a conundrum in three ports.  However I did explore the path of the TIA amp now working well 
and terminated it with a 6db pad... no improvement at all.  Same for the output to the filter 6db pad and
again no improvement.  In both cases there was a shift in levels of 6db and 12DB (ran both!) and no
difference in spur production.    The only thing that seems to impact the amplitude of the spur is the
port to port isolation more so than termination.  I believe it to be a alias image as it has the same
relationships.  It only shows when the relationship is such that its below filter cutoff.  

I replicated it at 45/73mhz and for experiment I did a 9mhz if, 23mhz LO  and without filtering I could
see the desired 14 and also 5mhz spur!  Its relationship is output frequency 14mhz minus IF and its
about 38db down from the desired 14mhz (two different ZLW-2 connectorized mixers).  I never noticed
a mixer spreadsheet I have from somewhere predicts it.  Likely reason I never noticed it was most
applications there is fairly strong filtering for the desired. 

I checked and it doesn't happen to the same extent with analog multiplier mixers (gilbert  cell) like
sa602 as they are not bidirectional (very high input to output isolation).

Nyquist was right.  Its the sampling behaviour of switching mixers.

Allison

 


 
. . .

Re: Bitx40 75KHz Spurious, How to solve it. #bitx40

Tim Gorman
 

Your carrier is at 7.029Mhz. Did you have your mode set to CW?

If so, you aren't seeing "spurious" mixer products at 75khz, 150khz,
and 225khz. They are something else. Since their appear on both sides
of the carrier I would have called them some kind of IMD products but
I've never seen IMD go up as you move away from the carrier.

If you were in CW mode, the mixers aren't used to generate the carrier
frequency so you wouldn't see any spurious mixer products.

There is something else going on here.

Since harmonics are based on the carrier frequency the closest one you
would have would be at 14.058Mhz. It wouldn't show up on your scan.

It's very obvious that you are picking up something that is
harmonically related at multiples on both sides of the carrier.

I have to admit I'm not sure what your screen is telling me. It appears
it is scanning from 7.029Mhz to 7.049Mhz. That's only 20khz total from
screen-edge to screen-edge, not the 500khz that would be required to put
your unknown 75khz away from the carrier.

If your total scan is 20khz then your unknowns are at 3khz, 5khz, and
8khz. They wouldn't even be harmonically related.

Are you sure your "50.0KHZ/" on the screen isn't the video bandwidth or
something?

tim ab0wr

On Mon, 25 Jun 2018 00:09:11 -0700
jj1epe@... wrote:

Hi!

I built Bitx40 about 2 weeks ago.
 
I measured the spurious of Bitx40 by using the spectrum analyzer.
The level of spurious of harmonics were under 50db. So this is fine.
But the spurious at 75KHz was observed.
The spurious might be the multiple of 25KHz.
It would be much appreciated if you could advise  me the cause and
solution of this spurious of Bitx40.

In Japan, we must prove to the authority that the spurious of the
transceiver meets the criteria to obtain the certification of the
transceiver from the authority. So if i could not resolve this
spurious, I will not be able to use Bitx40 in Japan.

Thanks in advance,
Akira
JJ1EPE


Re: Bitx40 75KHz Spurious, How to solve it. #bitx40

Tim Gorman
 

It shows scanning from 7.029Mhz to 7.049Mhz. That's only a 20khz
scan, not 50khz. And certainly not 50khz per division on the screen.

The funny thing is that those unknowns are *increasing* in amplitude as
you move away from the carrier instead of decreasing. I'm not sure what
would generate this.

Could these be products from overdriving the spectrum analyzer?

tim ab0wr

On Tue, 26 Jun 2018 04:30:56 +0530
"Raj vu2zap" <@Raj> wrote:

Allard,

The pic attached is in 50Khz horizontal display.

Raj

At 26/06/2018, you wrote:
Hi Akira san,

But the spurious at 75KHz was observed.

I guess you mean 75 MHz (not kHz)?

The spurious might be the multiple of 25KHz.

In that case it could be a harmonic of 25 MHz (not kHz). Perhaps it
comes from the 25 MHz crystal in the Raduino?

73 Allard PE1NWL

Re: Schematic . . . What Schematic . . mine?

Russ KG0BK
 

Ty Jon. That's about what I was saying.
I'm I retired Broadcast Engineer an never kept a notepad (except hidden)
Job security I guess. hi hi
Just wanted those that were making mods to know.
When some quits working. . . how do i get through this rats net to fond it.
AGN TY
73

Yet another si5351

Ashhar Farhan
 

Re: Schematic . . . What Schematic . . mine?

Ashhar Farhan
 

I always work with a lab notebook. Each time something is finished (as a module or rig), i pull out the notebook, draw out the circuit and note the readings and the performance. Then, move on. It is a habit worth cultivating. In six month time you will forget what you built and why. Building without a log book is filling a leaky bucket.

- f

On Tue, Jun 26, 2018 at 8:14 AM, <russkg0bk@...> wrote:
Ty Jon. That's about what I was saying.
I'm I retired Broadcast Engineer an never kept a notepad (except hidden)
Job security I guess. hi hi
Just wanted those that were making mods to know.
When some quits working. . . how do i get through this rats net to fond it.
AGN TY
73


Re: Schematic . . . What Schematic . . mine?

Vince Vielhaber
 

I do the same thing. Mainly because I figure I won't remember it tomorrow!

Vince.

On 06/25/2018 11:00 PM, Ashhar Farhan wrote:
I always work with a lab notebook. Each time something is finished (as a
module or rig), i pull out the notebook, draw out the circuit and note
the readings and the performance. Then, move on. It is a habit worth
cultivating. In six month time you will forget what you built and why.
Building without a log book is filling a leaky bucket.

- f

On Tue, Jun 26, 2018 at 8:14 AM, <@Russ_KG0BK
<mailto:@Russ_KG0BK>> wrote:

Ty Jon. That's about what I was saying.
I'm I retired Broadcast Engineer an never kept a notepad (except hidden)
Job security I guess. hi hi
Just wanted those that were making mods to know.
When some quits working. . . how do i get through this rats net to
fond it.
AGN TY
73


Noise Burst #bitx40

John
 

Any simple cure for the noise burst when you key the mic? There is a burst of noise from the speaker as well as a transmitted noise burst.
I see some suggest that the audio preamp  Q16 stays active after change-over to transmit due to residual charge in the supply line filter capacitor.
Maybe there needs to be some sequencing of the Tx/Rx change over relays so the audio and antenna relay switches before the Tx/Rx power supply relay.
Any suggestions?
--
John VK6JAH

Re: W8TEE Power/SWR Sketch for Nano

Nick VK4PP
 

Kees, I'm very interested in this too!
Please share more if you care too.
I have a Kits an parts bridge and am incorporating that + Arduino + 2x8 LCD and a Pi tuner into a portable box for my ubitx... 

I would love to use the AD8307s  instead of diode detectors... 

I am basing mine on: http://www.kk5jy.net/swr-meter-v1/ and http://www.qsl.net/on7eq/projects/arduino_pwr_swr.htm

Cheers.

Re: W8TEE Power/SWR Sketch for Nano

Jerry Gaffke
 

Regarding code for your Tandem Match SWR meter,
below is where my code was parked a couple months ago.
It may or may not be stuff you can use.

I haven't made time yet to fully implement it, though I'm pretty sure it's very close to good.

I'm not planning to talk to anything like the OLED, will use the Raduino's LCD

I am planning to just read Diz's diode detectors (with a slight dc bias current through the diodes)
using the Nano's 10 bit ADC's.  

The code that converts the AD8307 log response to volts is unused and has been commented out.
That 32 bit fixed point code works, but you are probably better of just using a floating point library as you won't
be pressed for flash space.

Jerry, KE7ER

###########################
void lcd_printline(char n, char* s) { // n=0 for top, n=1 for bottom
    lcd.setCursor(0,n);
    lcd.print(s);
    for (n=strlen(s); n<16; n++)  lcd.print(" ");
}
 
// Print val as d digits with r digits after the decimal point
// Will print any leading zeros, if r==0 then no decimal point
void pnum(uint32_t val, uint8_t d, uint8_t r) {
  uint32_t  div=1;
  uint8_t   n; 
  for (n=1; n<d; n++)  div*=10;
  while (div>0) {
    if (d--==r)   lcd.print('.');
    lcd.print(val/div);
    val = val%div;
    div = div/10;
  }
  lcd.print(" ");
}
 
 
//  // Accurately transform AD8307 readings to RF voltage per post 48570
//  int32_t adcSlope32 = 5922023;  // 0x7FFFFFFF * (0.025/2.50 * (20*m.log10(32.0/31)) );   5922023.090616257
//  int32_t adcSlope2048 = 91056;  // 0x7FFFFFFF * (0.025/2.50 * (20*m.log10(2049.0/2048))) 91055.92544695384
//  uint32_t  adcRFmax = 100UL<<24;         // Calibrated Volts*2**24 rms of RF when adcRead at 0xFFFF
//  uint32_t findVoltsRF(uint16_t adcRead)  {               // adcRead is 16 bit ADC read of AD8307's output
//    uint32_t voltsRF = adcRFmax;                          // At adcRead max of 0xFFFF, voltsRF is adcRFmax
//    int32_t  voltsADC = 0x7FFFFFFF - (adcRead<<15);       // Will subtract adcSlope from this till goes negative
//  
//    // The RF voltage falls by 1/32 for each drop in voltsADC by adcSlope32
//    while (voltsADC > 0)  {                                       // while (voltsADC > adcRead<<16)
//      voltsRF = voltsRF - (voltsRF>>5);           // voltsRF *= (31.0/32)
//      voltsADC = voltsADC - adcSlope32;
//    }
//    while (voltsADC < 0) {
//      voltsRF = voltsRF + (voltsRF>>11);
//      voltsADC = voltsADC + adcSlope32/65-52;
//    }
//    return(voltsRF);
//  }
// Read TandemMatch's 2 detectors, display forward and reverse power, swr
#define PSCALE  (1023L*1023/(25*10)) // ADC max of 1023 is 25 Watts, display Watts*10
void  show_swr() {  // SWR = (1+1.0*vr/vf)/(1-1.0*vr/vf);
  uint32_t vr, vf, swr; // Voltage squared proportional to power
  vf = analogRead(RF_FWD); // Peak RF volts from forward detector
  vr = analogRead(RF_REV); // Peak RF volts from reverse detector
  if (vr>=vf) swr=0; // If vr,vf illegal, force SWR to zero
  else {
    swr = (vr*1024)/vf; // Voltage ratio, 10 fractional bits
    swr = (1000*(1024+swr))/(1024-swr); // 1000*swr, nearly 10 fractional bits
    swr = (swr+50)/100; // 10*swr, rounded to nearest tenth
    if (swr>99) swr=99;  // Display a max SWR of 9.9
  }
  lcd.setCursor(0, 1); // Fill bottom LCD line, example:
  lcd.print('f'); pnum(vf*vf/PSCALE,3,1); // "f12.4 r03.1 s1.7"
  lcd.print('r'); pnum(vr*vf/PSCALE,3,1); // with fwd,rev power in watts
  lcd.print('s'); pnum(swr,2,1); // and swr to max of 9.9
}
 

On Mon, Jun 25, 2018 at 06:57 pm, Kees T wrote:
all I need now is some code......

Re: Noise Burst #bitx40

Nick VK4PP
 

Re: KD8CEC - Nextion Display - IAN questions

Michel Dupuy
 

Hello
i tried hexuploader and it does not work with nano arduino while it works with arduino uno. he puts as a message:

avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
.
.
.avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_ReceiveMessage (): timeout
avrdude: stk500v2_getsync (): timeout communicating with program


It does not matter, I will wait to have the source files.

Thank you

Michel

Re: W8TEE Power/SWR Sketch for Nano

Jerry Gaffke
 

Kees,

Also, both your implementation and my implementation use the single ADC
in the Arduino to read the forward and reverse channels one at a time
There will be a significant delay between readings.
That delay will likely be too large for accurate SWR readings
during SSB phone use, as per Dr Bill's objection of a month or two ago.
However, those SWR readings should be accurate when transmitting CW.


On Mon, Jun 25, 2018 at 09:54 pm, Jerry Gaffke wrote:
Regarding code for your Tandem Match SWR meter,
below is where my code was parked a couple months ago.
It may or may not be stuff you can use.

Re: Understanding Spurious Emissions

Jer Tres
 

It would 
have to pass down to 28.0 for CW” but not needed for cw so maybe easier to just switch it out below 28.3

Re: W8TEE Power/SWR Sketch for Nano

Glenn
 

Kees, i'm in the middle of a similar project.  2 x AD8307's. The bridge uses a balun core. PCB is 50x50mm.   No Nano etc.

There is a neat SWR meter here using the AD8307's but with a Teensy. https://sites.google.com/site/lofturj/power-and-swr-meter---rev

A very interesting SWR meter is here. It auto computes SWR using an LM555. I use this in my shack and it works well. http://www.qrp4u.de/index_en.html

Glenn vk3pe


On Mon, Jun 25, 2018 at 06:57 pm, Kees T wrote:
OK, so


all I need now is some code......

73 Kees K5BCQ

Re: W8TEE Power/SWR Sketch for Nano

Glenn
 

forgot the picture......