Both CW and SSB are making rated power.

I assume you are checking for power out in CW mode.
Does the transmitter work in SSB mode?
That would prove out the modulator/demodulator, the 12mhz crystal fllter, and the 45mhz crystal filter.
None of those are involved when transmitting CW.

Just finished wiring up my V.4 kit from Farhan. I have the EXTREMELY low receive issue. I have rated power output on transmit and very loud CW sidetone audio. What RX audio that I can hear (from a local broadcast station) is quite clear and understandable. Anyone have any thoughts/guidance?

I have tried the calibration and BFO setting and neither one seems to do any good. I have loaded the CEC firmware, but this was present before that.

Here is an interesting library that lets you control the Raspberry Pi GPIO pins with much the same simplicity as the Arduino I/O library.



Tom, wb6b

On Tue, Aug 7, 2018 at 07:49 PM, Howard Fidel wrote:

I picked it up for $5. Not sure what to do with it, and it needs special mating cables to use it.

That's why I paid $10 and got it with onboard wifi. I run it headless via PuTTY or VNC. ?
?
--

Hi guys,?
I built the little s-meter circuit at this page:

I have checked my wiring 3 times, and it all looks like it is correct.
I have a 3.2" nextion display.
everything works nicely, but I do not see any S-Meter indication.

any ideas ?
is there something I have to activate ?
kevin rea
lancaster, calif.
k6rea

It is possible to use a square wave as the signal source in a VNA.

I looked hard at the N2PK VNA a few years ago, that is a sine wave source
into the DUT, and the signal out of the DUT is inspected by two mixers with a LO
at the same freq as the DUT source but in quadrature,?outputs at DC.? (Now that's baseband!)


The W5BIG AIM430 VIA creates 2 sine waves from DDS chips for DUT source and an LO to the mixers,
the two mixers effectively measure?current and voltage from the DUT into a load resistor.
The mixers get sampled with ADC's and that data is passed on to a PC for an FFT to?
find the amplitude and phase of the two 1khz audio signals (which represent RF voltage and current)
He's got it pretty well described here:??http://w5big.com/QST_Article.pdf

The DG8SAQ VNWA is similar, but he's got that thing wound up to work well at some
very high frequencies, far higher than any of the data sheets for the parts being used
would suggest possible.? Well regarded, and very accurate.? Not cheap.
Mixer outputs are at a few khz, as I recall.
He's sellng lots of these, does not provide complete instructions?on how to go into competition.
?
The AQRP VIA that Kees sells is is similar to the AIM430.? The big difference here is it
gets by using all square waves.? An FFT is carried out by an on-board ARM processor,
and by ignoring all but the 4khz difference frequency between DUT source and the LO to the mixers,
it can ignore the harmonics in the square wave.? It has recently been extended for use
as a two port VNA.? A nice self contained unit with touch screen at a good price.
? ??




From post 56160:
>? I'm seriously considering putting together a signal analyzer along the lines of your earlier post.
>? ? ? Step_Attenuator -- 50mhz_LPF -- diode mixer -- MMIC_Amp -- PX1002_SAW -- ad8307 -- Nano_ADC
>? In parallel with the AD8307, add an SA612A plus audio amp so I can hear it.
>? There's lots of information in that audio if you know what to expect.

If instead of one SA612A we have two mixers driven with quadrature LO's, we could use SDR
techniques to separate upper and lower sidebands in an ARM processor.
But then we have pretty much all we need for an AQRP style VIA.
Hence the creeping featurism that prevents me from ever getting out the soldering iron.

Of course, it would take me a year to figure out the DSP software involved.
Just listening to an AD8307 with an ADC makes the software trivial.
And gives us a spectrum analyzer perfectly suitable for poking at a uBitx with.

Jerry,? KE7ER

What is interesting about the spectrum analyzer screenshots is the harmonics do not get progressively weaker with increasing frequency.?

There is a lot of current flowing across the board to the finals. It could be the harmonics are coupled common mode into the grounds, at the capacitors, of the filters.

Providing a more reliable ground across the uBITX board, via low resistance connections, through metal standoffs, to the four corners of the board might help. ?That was the thought, anyway.

Tom, wb6b

You could, send commands to it via serial (2 pins clock and data).
?
Using? 2 pins and a 74166 would get you 8 outputs and potentially 8 inputs too
if you add a 74165.
Or the same two could go into a 74138 to get a 2:4 decode or 3:8 decode.

You can also multiplex the 4 pins for the LCD as they cause no display
changes without R and E signals so those 4 with a single pin could be
latched?to add pins.

Allison

Is the list down?

开云体育

Last one I bought was $10.

--

Would it be useful to piggyback a second Arduino simply to provide another bank of I/O ports?

John
KC9OJV

I just bought a refurbished HP on Amazon. 3.4G processor, 8G of memory and a 500G hard drive. $230. The kid next door is putting Windows -7 on it.
--
John - WA2FZW

Jerry,

The basic theory is phase of source and phase of returned signal, S11 Rx,Jx is the result
or reflected (referenced to 50 ohms) voltage and phase.? To do that you need to do
phase comparison and mixers like DBM can do that.

There are two systems in use to do that one uses a current measurement and voltage?
and compared those to reference (source signal) the other uses directional couplers
and refernce their output to the source.? The source has to be clean sine.??Once you
have phase and amplitude data (basically S11) you can calculate the result and
plot it as smith, polar, or as desired.? Not trivial but not rocket science (logs trig and
a little vector math).

Both require a clean sine source as harmonics will render teh results useless.? Simple
example is MFJ259B.? FYI if the source has issues in the 259B the readings are bad
and part of calibrating it is verifying the output has minimum (-40dbc) harmonics.?
I've replaced the diodes in mine and recalibrated it.??

Allison