R136 measures 97ohms regardless of setting...does this mean anything?

I am also looking for a Multiband hf transceiver kit but with no luck, can anyone out help...

I'm about to buy a bitx20 v3...I would like to know if someone has put 4 line by 20 lcd which has a s-meter in it for the 20 meter...

I'd guess those figures are more like 102ma and 230ma.
And that you are not be including the Raduino in those figures.

You might look over the rest of these links once you've sorted out the above readings.
??/g/BITX20/message/33943

Jerry

Thanks Jerry for correcting my reference for the 100pf mod to the LPF.? I meant no disrespect.? Simple ignorance.

-So I have confirmed that my antenna is wired correctly.? COM to bnc shell, board antenna connected to pin, no continuity between shell and pin.
-I was also able to measure mA (thanks to the patient instruction of Dexter N Muir)

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I am working on a PCB with that alternate part.? It is in a 20 Pin package.? It has 8 clocks and one address pin.

I have jumpers for the address and the spread spectrum option.

I have made one with the $1 part and like on this one, I put a resistor and then a 10uF cap on each of the clock supply lines.

This should help with current hogging and give the user the ability to increase the resistor for experimenting.

It has its own 3.3V regulator and proper level shifting, so it only takes 5V, Gnd, SDA, and SCL to run.?? It should be able to run along with

the Raduino SI Gen part without much interference.

I attached schematic "LotsaClocks1".?? PCB is almost done.

Mike, WA6ISP

The si5351 costs $1. ?Perhaps use one exclusively for first LO, another for second LO and BFO.
Stuck at same i2c address, but perhaps an analog switch to select one or the other.
Or use one of the other si5351 variants, they have separate vddo pins for each output.

On Thu, Oct 26, 2017 at 01:39 am, Jean-Matthieu F5RCT wrote:?

The most critical will be purity of the first LO. The 57 MHz and the BFO are less critical since the signal is filtered by Xtal filters.

?

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
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Yes, I was wondering about using a needle to get the turns nice and tight. I was also wondering, when they refer to a bifilar winding if you are supposed to make a twisted pair prior to winding on the core, or just wind two parallel wires, or if it makes a difference. Any further info would be helpful before I rewind the core.

Thanks

Brent

The si5351 costs $1. ?Perhaps use one exclusively for first LO, another for second LO and BFO.
Stuck at same i2c address, but perhaps an analog switch to select one or the other.
Or use one of the other si5351 variants, they have separate vddo pins for each output.

On Thu, Oct 26, 2017 at 01:39 am, Jean-Matthieu F5RCT wrote:?

The most critical will be purity of the first LO. The 57 MHz and the BFO are less critical since the signal is filtered by Xtal filters.

?

Hello Sarma and Jerry,

?

Thank you for your suggestions !

I plan to build something simple and not with tens of BPF and amplifier and so on….

?

During my studies I spent 6 months as training in Thales and my project was high IP3 mixer at > 40 dBm input with 33 dBm LO !!!

So I know about mixers and how to drive.

Having a high level of LO is mandatory to get the best performances, It is much better if the LO is square shaped.

I’m not convinced that driver a diode ring mixer at -10 dBm is sufficient, normally it is +/- 3 dB around nominal level to guaranty conversion losses and IP3i.

I’m using +7 dBm Mini Circuits mixers TFM-2, SBL-1,… they have high LO rejection.

Close to the mixer I have a 3 dB attenuator.

?So I hope if the spurs are below -60 dBc it will fit !

?

Jerry, your idea of the internal 3.3v rail may be getting jerked around is possible.

I will try to reduce the output drive current first.

About the layout if the Raduino I see a ground via a little far from IC pins, that’s not good for common mode grounding…

In SiLab layout recommendations they say that both Vcc pin must be decoupled…

On Adafruit PCB I see a GND plane under the chip and GND on both sides with many vias.

?

The most critical will be purity of the first LO. The 57 MHz and the BFO are less critical since the signal is filtered by Xtal filters.

?

In the next step I will continue to build the receiver chain to BFO output and do some tests !
Now, front end is done and I'm at the 12 MHz IF (Xtal filer, AGC amp,BFO..)

?

We don’t know if Farhan’s Ubitx will be finalized in hardware and software ?

..or if he lets the community to continue his project ?

73 de F5RCT

Thanks John

That's what I figured. I tried it with the number 30, and the amp works, but output is low. I'll try to make a different core. The instructions specify 5 bifilar turns on the primary, and 10 on the secondary, so I guess that works out to a 2:1 ratio with the center tap.

Brent

Just got my e-copy of Nuts and Volts for November 2017. Page 36-40 has the Bitx20 project.


Sent by me

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Thanks!!

Brent:

Probably not.

A viable alternative to the small "pignose" core
is a slightly larger one two of the same size mounted
back to back, or using four FT37-43
or FT37-61 cores cemented as two pairs of
two each side by side, and made to look sort of
like a "pignose. If necessary, go to a FT50-43 or
61 toroid core. It is not too critical; what makes a difference is
the number of turns and the ratio of turns in the
output transformer. You are trying to match the AB
transistor section to 50 ohms for the antenna. Usually
that is a ratio of about 4:1...but it may not be. There is
a lot of information on the JBOT out there. Look it up for other
alternatives. All of them will work pretty well. You may also
have to add a small capacitor across the primary winding
of the output transformer to squelch oscillation. (It happens!)

I don't know what Sunil is using, but most likely it
is a type #61 core (since these are everywhere now
as they are the common core of the 300/75 ohm transformers
for TV antenna lines). The original source is on Farhan's home
page. Look it up; it is very interesting.

john
AD5YE

I realize this isn't part of the bitx, but it was developed in the same spirit as the bitx project, so forgive me if I ask a few questions. Firstly, if anyone has built this, can you give me any advice on the output transformer. I purchased Sunil's kit, and am having difficulty fitting the #26 wire on the binocular cores for the output transformer. I have some #30. Will using this much smaller wire degrade performance very much?

Thanks

Brent

Here's some DC readings:
/g/BITX20/files/K7AGE
And some AC:
/g/BITX20/message/22764
A few random hints:
/g/BITX20/message/24225
Might be something more here, not sure:
/g/BITX20/message/23640
Maybe here:
/g/BITX20/topic/5181681
And an LTSpice simulation of Q13,14,15 here:
/g/BITX20/files/ke7er

Typically, it's in one of the many torroids. between Q13 and the antenna. ?Perhaps a broken wire, or shorted wires,
or enamel left on the wire where it was soldered to the board, or a cold solder joint.
Or something embarrassing, like a poor connection between board and antenna BNC.
You can often find those problems with an ohmmeter.

Stuff behind Q13 except the transmit side of the bidi amps is common to both transmit and receive,
so less likely to be the problem. ?But a 10 db loss in a mixer, for example, would mean very little
transmit power out, but not even noticed on the receiver.

Good luck!
Jerry, KE7ER

well I removed d7 and c130 and it doesn't smoke anymore but still not working. I hooked up the antenna. makes weird noise from speaker with no static but what I did notice is if I tune around in different spots it sounds like I can hear jumbled voices.
I will probably end up ordering another board and tackle this again later on when I feel more advance or there is a guy at the local ham club that has a lot of experience with electronics. Maybe I will ask him if he wants to look at it with me

Yes, the mic is a Baofeng style handset.? It seems to me that I ended up switching two of the leads from the Miklor diagram to get mine to work as well.? Unfortunately, I do not remember what exactly was switched.? I do know that the speaker works though.
I have tested the PTT function using the PTT switch supplied by HFSigs.? I guess if the mic is not wired correctly, I wouldn't get a response from the switch alone.? I should try the supplied mic as well.

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Is there a document that shows the proper DC and AC/RF voltages at various places on the latest BitX40 Board from India?

My receiver is working, I’m now trouble shooting the transmitter.?