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Yes build it stock first and get it working then do the updates/mods. This will make it easier troubleshooting anything that may be wrong.?

I just received my kit in the mail.
I also have a Nextion 3.2e...
do you think I just build it all stock first and then do the mods such as the screen ?

Kevin

Just finished my first ubitx v4 build and things are not working as expected...Thanks first of all for any and all help. My main symptom is that on power up the display is showing a string of blocks on the bottom row.. Somewhere about two thirds to the right is one blocking dimly blinking. A quick disconnect before something went poof and subsequently with longer power on no change was had. I then plugged some ear buds into and could here some birdies and other odd sounds etc. as? I turned the tuning control. Have any of you all had or know of what this problem is or points too. I know this isn't much info to go on but all support/help/advice is appreciated.

73
chuck

do you have gerbers for this project to have the board printed and a bom file ?

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The "dB SPL" gives the Pascal part of 1V/Pascal, but it does not specify the 1V part.

94 dB SPL means 94 dB above the reference sound pressure level of 20 uPa,
where 20 uPa is around the bottom threshold of human hearing.
? ??
When somebody says a rock concert has a sound level of 110 dB, they mean 110 dB SPL.

So? a complete spec for microphone sensitivity might say how many "dB SPL" to give 1V out.
Or they might say how many "dB" to give 1V out, and mean the same thing.
Those acoustic engineers only deal with one kind of dB, and assume any such figure is for dB SPL,
and describes a measured sound pressure level, not a ratio.

In radio work, "dB" refers to a ratio, perhaps the output power of an amp divided by the input power.
To give a power measurement we might say 20 dBm, which is the ratio of the 100 milliwatts we measured
divided by an inferred reference of 1 milliwatt:? ? ? 10**(20/10) = 100.?
So dB is a ratio of two powers, and dBm is a specific power level.?

######################
While I'm on a rant, here's a bit more for those still puzzled but vaguely curious.

I've said that dB in radio work means a ratio.
A good receiver might have a dynamic range that can simultaneously deal with incoming
signals of both one microvolt and one volt at the antenna, and still allow us to hear
the small signal.? Since power is the square of voltage divided by resistance,
that's a power ratio of 1,000,000,000,000 between the big and the little signal.
These numbers quickly got out of hand, especially for those folks back in 1930 working
with a slide rule.

It might be easier to say that the big signal has 12 more zeros after it than the little signal.
Though that isn't very precise, if the receiver front end was improved to deal with
a big signal of up to 2 volts it would then have 12.6 more zeros than the little signal.
(Those who remember high school algebra will understand how to deal with a fractional power of ten.)
Rather than deal with fractional numbers like that, they decided to just multiply the zero count by 10,
so we can now say that a receiver capable of dealing with signals between 1uV and 2V has?
a dynamic range of 126 dB.?

Through the magic of logarithms, when the gains of two amps in series are expressed in dB we can
determine the total gain of the amp by adding a couple 2 digit numbers in our head instead of multiplying
out a couple larger numbers.? You don't see dB used much in hard science such as a physics textbook,
they just deal with the big numbers.? But radio engineers who live and breathe this stuff 12 hours/day
needed an easier way to do the calculations in their head, and dB won out.


The formula to go from a power ratio to dB is? 10*log(P1/P2).
Here, "log" is base ten, and log(1000) is 3.
For even powers of 10, the log() function just tells us how many zeros.??
In the case above, we have 10*log(2000000*2000000/1) = 126 dB
(where voltages are expressed in microvolts).

I usually use python as my calculator when figuring out this sort of thing.
It's available for almost every computer (unfortunately a Nano is too small)
and fully interactive, highly recommended.? The log function comes from an
external library called "math", so we must first bring in that library to make it available.
Here's a python session to test the above formula, it gives a more precise result
than my approximation of "126 dB".:

import math
10*math.log10(2000000*2000000/1)
>>>? 126.02059991327963

We can go from dB back to a power ratio with this:
10**(126.0206/10)
>>>??4000000079872.417

and go back to the voltage ratio by taking the square root of the power ratio:
math.sqrt(4000000079872.417)
>>>??2000000.019968104


Jerry, KE7ER

--
Mike
AI4NS

Allison wrote:

"For ubitx (V3 or 4) a pair of back to back 1n194/4148 diodes from K3 Pin14 to ground
is the best bet as then its only there for RX and has no impact on TX."?

If there is a possibility that these diodes could cause spurs during TX (which I doubt), then it seems the safer approach is to connect the back-to-'back diodes from K1 pin 12 to ground.? K1 pin 12 is grounded and isolated from the RX/TX circuitry connected to K1 pin 14? during TX, which guarantees that the diodes can't cause spurs during TX.? Placing the the diodes from K1 pin 12 to ground should still provide the same protection for Q90 during receive as connecting them from K1 pin 14 to ground.?

73,

Carl,? K0MWC

Guess I should have watched your video first as you said everything I just said:-(

Joel
N6ALT

I built and installed the Kees AGC kit yesterday but dang thing would not work.? Waited until today to check it out.? A close look at the board showed that every component was soldered properly with no solder bridges or other issues.? But then, I noticed that pins 1 and 2 at the top of the board hat a "J" printed above them with a jumper symbol.? ?That's when I re-read the instructions from Don that stated "if you are not installing an RF gain control you must jumper pins 1 and 2".

Well, DUH!? I chose to not install an RF gain control.? Once a jumper was soldered all is good

Posting in case anyone else has a tendency to not read instructions slowly enough......

73, Bill NZ0T

Thanks peter,

Leon at ozqrp puts these into all his rigs. I find them to be useful tools to show power output and sufficient SSB modulation.

Joel
N6ALT

William, you could consider the road that SM0JZT has taken. He installed a G4HUP buffer amplifier and uses an RTL-SDR dongle externally. This gives you the best of worlds - a low-cost transmitter and an equally low-cost SDR receiver. I have also bought the buffer amplifier, but will wait with installing it until the winter.

Just to throw in another way of specifying microphoen sensitivities . 1V/Pascal is equal to 94 dB SPL.? So you may see either terms when looking at mic specs.

Greg
K1YW

On Wed, Jul 18, 2018 at 07:52 AM, Richard E Neese wrote:

I have a ubitx v4 it was workign fine on my 12v 3 amp power brick all fo a sudden whip transmitting the unit shut off and cam back on.

Mine did that, too, because the current draw was too much for the PS, and the PS turned itself off and back and on.? That can happen (at least in my case) on lower bands with a bad antenna mismatch.

I did not have further issues like you describe.

Sadly based on the data sheet I got some MPSH10s and as reported they didn't perform as expected.

The devices I found worked better for me are:
2n2222A(to18), I tried PN2222 and they?produced less power (better than 3904).
2n2219A,? the same as 2n2222A (they are the same die in different package)
2n3866
2n5109

I also tried a pair of irf510 as drivers with suitable mods for bias and they worked
fairly well. The transformers for predriver and driver were less than optimum using
those.? ?I also tried the 2n6661As and they were about the same as IRF510 and?
for those that might consider it 30* the cost of IRF510, and 9* the cost of 2n2222A.

Others that might work if you have or can find them are:
MRF495, 2sC799, 2sc1306, 2sc1307, 2sc2166

Most of the effort to get not more power as you will get that but more even power
ended up with changing the transformers for better impedance matching at higher
frequencies.? My goal was 10W plus or minus a few and decent power at 10M.
If your pushing for more power in the 80-17M range the 2n2222A is a winner?
in the driver and pre driver along with bias changes already discussed.

Allison

You might want to check the power supply too. If something in it died, you might be getting ac on the power lead which could cause this symptom.

Mucking with RV1 could easily and quickly blow the IRF510.
Whenever adjusting RV1 (the IRF510 gate bias voltage), you should be monitoring?
the drain current into the IRF510 (12v into PA-PWR1) with an ammeter.
RV1 should be set for 100ma and no more (with no audio into the mike), it's very touchy.
At that point (100ma) the IRF510 is just starting to conduct, a little bit more and it will be several amps.
I'm a bit surprised it stopped at 1.6A, perhaps you have a weak power supply, could have been 10A.
Assuming 1.5A going up as heat in the IRF510, that's 12*1.5 = 18 Watts into a very inadequate heatsink.
Will be smoking hot.

This RV1 on the Bitx40 corresponds to RV2 and RV3 on the uBitx (there's two IRF510's on the uBitx).
Same rules apply, don't mindlessly twiddle those pots or you will blow the final.
Should be 100ma into each IRF510.

Twiddling R136 on the Bitx40 and RV1 on the uBitx adjusts the drive level into the transmit pre-amps.
Somewhat less dangerous, as it probably won't cause the IRF510's to blow across the room.
But turning up the gain too high there will cause distortion in your transmitted output
and you will be splattering across the band.
On commercial rigs, this is much like turning the mike gain up too high.

When going for more power by adjusting those pots or increasing the voltage into the IRF510 drain
or when going to long duty cycle transmissions (perhaps digital modes), a good idea to check if
the IRF510 heatsink is getting hot.? If it's too hot to hold your finger on it, that's too hot.

Jerry, KE7ER