if any of you folks need a new pc, here is a very good deal..

If C52 and C64 are isolated by diodes then the RX and TX voltages will have no large capacitors to filter low frequency noises. ?It might not be a problem here but I've had a number of "unexplained" problems turn out to be a lack of sufficient filter capacity. ?

73,

Tom ?W1EAT

Its not obvious so I'll try to explain.

Lets say we have two transformers (any for the moment save for they are the same).

Also the transformer have a separated primary and secondary as that makes it easier to see.

So we hook them up back to back and hook the primaries to the tracking generator and the?
spectrum analyser input.? So far we have complete circuits that do not depend on any
circuit common or "ground".

For that case if I said the transformers did such and so we can see and evaluate it.

Now what if...? I break? the back to back connection for one lead and insert 2M
of wire nicely laid out on the bench would you be happy with that?? ? I know I would
not as that 2M of wire is about 2.6uH of inductance give or take.? So I'd expect the
trace to show some loss especially at 28mhz? especially since that 2.6Uh is about
480 ohms of reactance.? ?Please do not argue the amount of inductance its
magnitude is less important than the fact that its there at all.

So if I go back to the back to back original transformer and instead take the other
leads apart and connect them to the input side shield of the coax what have we?
THe secondary are connect together via a 2M lead that also includes the frame
of the SA.? ?But the SA is ground.... no it has a common, but ground is likely about
3.5ft under it or more and the lead getting it to that mythical point is 3.5ft long or more
with its inductance.? IF you go to the 3 wire cord its 3-6ft long to the safety ground
pin on the receptacle which is not RF ground so it does not help and likely adds
problems to ponder. So as we follow the current around the circuit we find we have
a 2M?loop again and that loop has an added unknowns in the middle.

Its very easy to do this and not realize there is more going on but it is far from complicated
only that there are many parts to it.? Solution is to fix the test to remove that potential error.

Allison

I found that by simply increasing C1 to 2.2 uF (just parallel the existing 0.1 uF cap) the keying shape is greatly improved with about 3 ms attack and 6 ms decay. That is much better than the key click machine it was originally with about 0.5 ms attack and decay times.

73, Bob N1KW

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Thanks for your efforts so far.

Alan

Bob,

Try the ubuitx.net trick I poseted a day back.? The two cross coupled 3904s to pull the unused
power line to ground.

Allison

The cables add common mode inductance.? That is an incorrect assumption as a result.

We had this conversation before. In this stream.

?Allison

UPDATE!!!!!

I tried my earlier suggestion about putting a diode in series with R66 and it causes another problem. The energy stored in C64 keeps the mic amplifier running for about a half a second after releasing PTT, feeding mic audio into the audio output stages resulting in feedback and a nice squeal in the audio output! Maybe all (or half) of N3GO's solution would be better, at least for clamping the TX line.?

73,
Bob N1KW

Allison

The transformers have a common ground shared by the primary and secondary. The coax pigtails connected to the low impedance side of each transformer were, along with the low side of both high impedance windings, were all soldered together. The 1 meter pigtails were connected by N connectors to the tracking generator output and to the input of the spectrum analyzer respectively. So, yes, the grounds were connected in the back to back test.

With regard to seeking the permission of the participants in the email trail; no, I did not.

WA8TOD

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Mike, good cheat!

Me I pulled the connector and the pins and drilled three more holes and use
a PC mount SMA so it points straight up.?

Made testing easier and it looks cool.

Allison

Hi Allison,

Thanks for your help!

That what I thought so I order a replacement encoder from Digi-Key and installed it this morning still the same.

I just received my uBITX last week, it seemed to be working with a bit of hum but yesterday when I turned it on my encoder seems to have stopped working. When I turn the uBITX on the top line of the display reads uBITX v4.3 and the bottom line reads LSB A 7.149.950, when I turn the encoder shaft it changes only from 7.149.900 to 7.149.950! When I push the shaft in I get on the top line Band Select and an arrow that’s all that happens.

Best regards,

Is? ubitx_cat.ino in the same directory as the V4.3 code?

There should be 7 files:
ubitx_si5351.ino
ubitx_menu.ino
ubitx_keyer.ino
ubutx_factory_alignment.ino?
ubitx_ui.ino
ubitx_cat.ino
ubitx_v4.3_code.ino

Why does this happen?? Usually its because if the Arduino-IDE is loading a file for the
first time the file and the directory have to match and if it doesn't it will create it and copy that
one file to the directory.? However as your can see the sketch is spread across 7 files all of
which should be in the same directory.

The error message was the compiler saying "hey? you told me I need this and cant find it!"..

Allison

Wheck wires/wiring and then check the encoder for possible failure.

The fact that you get some indications of activity suggests it is broken.

Allison

Warren,

Did you ground coax at the transformer to the the other in the back to back test?
For clarity a piece of heavy wire from the coax connector of one to the coax connector
of the other transformer.

IF no, redo your work and report if there is a difference.

Allison

?Did the other participants grant permission to post that?? As that would be my
first question.? I see no such permission granted.? As such if they ask the mods?
to take it down I'd not?be surprized.

Allison

hi

i loaded ubitx-v4.3-code into aduino iide and clicked on compile/verify

the error message " checkCAT() not declared in this scope

what has gone wrong

note - i have no trouble in compiling the bitx40 code

terry gm4dso

Yes, the AGC mini-kit works with the Ver-4 uBITX board.

Ordering info and a lot more is in the "Files" section of this reflector under my call.

73 Kees K5BCQ

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