Date   
Re: Remote Head?

Dexter N Muir
 

As an ex-workmate put it (in false Irish brogue): "Good t'inkin', O'Rourke ... yer foired!" :)

73 de ZL2DEX

Re: Ubitx tx/rx "chatter" (read old thread)

Evan Hand
 

That seems to be a common problem depending on antenna and antenna connections.  I had similar issues with an off center fed dipole and RF on the coax braid.  Fixed it with snap on ferrites on the coax, others have used blocking baluns.  Also a .o1 to .1 mf cap on the PTT line to ground has been listed as helping. 

the above are my experiences and thoughts, YMV
73
Evan
AC9TU

Re: Ubitx tx/rx "chatter" (read old thread)

Kelly Mabry
 

Here is what I am using as a wiring guide. Specifically the 4 pin connector is the black as audio, brown as ptt and red as ground. Coming from the front left audio board, J6. (Sunil kit)
Kelly K5AID 

Re: Ubitx tx/rx "chatter" (read old thread)

 

Hi Kelly,

Looks like you should have Pin1 on the new mic going to the red wire connection on the 3-pin board connector.  Also you should have Pin2 on the new mic going to the black wire connection and Pin3 going to the brown wire connection (and no connection to Pin4).  Is this the way you have it?

73,


Mark

Re: Ubitx tx/rx "chatter" (read old thread)

Kelly Mabry
 

Not even close... doh... so embarrassing this is...

Will fix and retry...

Kelly K5AID 

Bitx 40

Earl Warhus
 

I would like to know if the brown wire from Raduino should be
grounded?
Thanks Earl Ve1awc


Re: Ubitx tx/rx "chatter" (read old thread)

Kelly Mabry
 

Update: chatter gone! I wired it as Mark directed, and it doesnt chatter!  

73 & thanks!
Kelly K5AID 

Re: Audio AVC

jim
 

Meets my criteria for a mod

(1) works
(2) minimally invasive
(3) dirt cheap, easily obtainable parts
(4) easy to remove (when it don't work)

Jim

On Saturday, April 20, 2019, 11:43:06 PM UTC, Jack Brabham - KZ5A <kz5a@...> wrote:


Looks like a simple solution to a complex problem.

73 Jack KZ5A

Re: uBitX PTT cycling

MVS Sarma
 

Hi Kelley,
Try to place on 1000pf (1nf) capacitor across the electret mic. Things should improve.
All the best. Regards
Sarma   vu3zmv

On Sun, 21 Apr 2019, 12:27 am Kelly Mabry <kmabry2007@... wrote:
Hi all! I have just connected a bc645 4 pin electret mic to my ubitx and am getting a 5 tx/rx "chatter" on transmit on a dummy load, when press ptt. When i release, all is fine, rx is lit and i hear rcv audio.  As a test, i enabled tx stop on the cec software,  and pressed ptt.  The tx indicator lights red for as long as i hold ptt, and then returns green as I unkey. This seems to indicate the ptt works as intended. After unselecting tx stop, the chatter returned. What am I missing? ...continuing to read thread...
73, 

Kelly K5AID 

Re: uBitX PTT cycling

MVS Sarma
 

Congrats Kelley, you solved it.


On Sun, 21 Apr 2019, 8:39 am MVS Sarma via Groups.Io <mvssarma=gmail.com@groups.io wrote:
Hi Kelley,
Try to place on 1000pf (1nf) capacitor across the electret mic. Things should improve.
All the best. Regards
Sarma   vu3zmv

On Sun, 21 Apr 2019, 12:27 am Kelly Mabry <kmabry2007@... wrote:
Hi all! I have just connected a bc645 4 pin electret mic to my ubitx and am getting a 5 tx/rx "chatter" on transmit on a dummy load, when press ptt. When i release, all is fine, rx is lit and i hear rcv audio.  As a test, i enabled tx stop on the cec software,  and pressed ptt.  The tx indicator lights red for as long as i hold ptt, and then returns green as I unkey. This seems to indicate the ptt works as intended. After unselecting tx stop, the chatter returned. What am I missing? ...continuing to read thread...
73, 

Kelly K5AID 

Re: Bitx 40

 

There are two, which one ?

Top smaller connector is the cw key AFAIK and bottom is vfo ground.

At 21-04-19, you wrote:
I would like to know if the brown wire from Raduino should be
grounded?
Thanks Earl Ve1awc

Re: uBitX PTT cycling

Kelly Mabry
 

Thank you! 

73,
Kelly K5AID 

Re: Audio AVC

Jerry Gaffke
 

I'm with Jim1 and Jim2, looks fine to me.
Under a buck in parts.
The sort of thing you could mount on the back of the volume control
with the only additional wire being +12v to power it.

For all my talk of the extra dynamic range you get with RF or IF attenuation,
this simple AF attenuation AGC circuit is good enough for most uBitx owners.
Solves the problem of tuning in a weak station, then having to tear off the phones
when the big gun across town opens up.  Only disadvantage is that the
big gun might be distorted due to overloading the audio pre-amp.
You already know if that will be an issue in your particular circumstance
by listening to the stock rig.

We've had a half dozen different circuits to do audio attenuation like this
get posted to the forum.  I suspect any one of them would work well enough.
Primary consideration is, does it allow you to hear background noise when
there is no signal, yet still sufficiently attenuate the strong signals.
Without distortion, of course.
Attack and decay times are also of concern, but that should be just a matter
of fudging a couple resistor values.

Regarding Scott's comment:
  "And because I’m a dinosaur I want to believe a decent IF-derived system is better,
    though I have to admit the ubitx audio-derived stuff is pretty good. :)"

IF derived AGC signal level sensing must be done after the 12mhz filter,
or it will de-sense on strong signals elsewhere in the band.
So that sensor will be right up against the demodulator, where we have a 7dBm BFO
hitting those diodes.  On the uBitx (and Bitx40), it would be very tough to avoid
sensing anything other than the 12mhz BFO, would require a bunch of shielding
and some sort of isolation stage between filter and demodulator.
I'll live with the occasional brief pop, and stick with audio derived AGC.

Of course, if you're a true dinosaur, you're operating AM phone.
No BFO, and thus no such trouble. 

Jerry, KE7ER


On Sat, Apr 20, 2019 at 08:03 PM, jim wrote:
Meets my criteria for a mod
 
(1) works
(2) minimally invasive
(3) dirt cheap, easily obtainable parts
(4) easy to remove (when it don't work)
 
Jim

Re: Menu Sequence for CEC Firmware v1.200 #ubitx #firmware

Dan Pflugrath
 

Hi John,
I edited the statements tonight and will compile and load the code tomorrow night after checking my code with a clear head.  I will let you know how it works.
73 Dan KA7GPP.  

Re: Audio AVC

Tom, wb6b
 

Hi,

It is a simple circuit. But it does have the component parts discussed in the “control loop” versions of the subject. As the original asker asked how they work, most of the responses explained the how.

 

The signal (as controlled by the FET) is reduced when the control (rectified audio) voltage goes up. That is the first 180 degree phase shift. Your example circuit just happens to have two RC time constant delays (C4 and C2). 

 

C4 looks to be a larger delay than C2 and swamps out the possible oscillation had both time constants been close to each other. (And, also, looks like it will respond faster to the audio peaks and delay slower due to the diodes).  

 

Unlike temperature, where one degree error could start a thermostat war between the members of your family or office coworkers, it was pointed out (in another post) that peoples response to sound level is logarithmic. So the gain of the control loop can be relaxed, and thus less components like additional amplifiers or comparators in the control part of the loop. 

 

This looser control of the volume level is actually an advantage; as it lets the listener get a sense of the difference between a strong or week signal without as much danger of their eardrums being blown out by the strong one.

 

The looser control (the lower loop gain) also makes the circuit less hair triggered to start oscillating right at the 360 degree total phase shift point. (Should the phase shift actually start approaching that point.)

 

If the delays of the control part of the loop (C4, C2) did start to go past 180 degrees, the AGC could oscillate. Causing a throbbing in the intensity of the audio as it raises and lowers the level of the audio, but is slightly behind in its reaction time to the audio level change. 

 

Also, with SSB, the control does not have a constant carrier as a reference for the signal strength. So it has to work around this by looking at the audio level or the peak RF levels in the IF chain. Then it has to apply additional things like fast attack, slow delay in the level adjustment to make up for the signals arriving in bursts as the transmitting person talks and pauses. 

Tom, wb6b

 

Re: Remote Head?

Ted
 

Dexter,

You bet it's Cheap-Old-Man compliant, better yet when it originates from a supply that I didn't pay for in the first place.  The variation and complexity of so thin a cable makes it ideal...... though an accidental discovery more so than a plan.  I was just looking toward the shielded, 15 wires inside! 


73,
Ted
K3RTA

Re: Audio AVC

Ted
 

This thread has been very educational for those of us who haven't dived into the front ends of a radio nearly as reply as we've done on the output or other RF sections.  Thanks, to all.

For what it's worth, I present here the Crowbar Method. It incorporates the best of a quest for maximum sensitivity along with absolute overload protection.  It began when I saw a post here for a sideband RF preamp from partsandkits, an item that I've added to both ubitx projects here.  My first stage of AGC begins with that board.

See here, the underside of the Zombie Apocalypse Survival HF Go-Kit -




Under the mainboard, the P&K he preamp is mounted convenient to the RX  signal path.




It's a pretty simple matter to add a 2N7000 or similar FET to short out the incoming RF signal (via a small ceramic cap, for a little isolation) and to use rectified audio from a LM386 to provide clamping drive.  The FET starts clamping pretty well with about .8v so experimentation with feed resistors and a touch of drain bypass was needed.




It so happens that I had already installed a kit board ND6T-style AGC which was working OK on its own,  but I still wanted a preamp for use with spotty woodland-based aerials during the upcoming apocalypse of the walking dead. So, that's why the Crowbar here is what I called a first stage while the regular AGC is now a second stage.  The bonus is that, being as I'm using the i2c-2nd-Nano S-meter mod, I do not require the ND6T board's S-Meter output for that job. 

I decided to use that output to replace the 386 clamping source and, somewhat surprisingly, there is no fighting or oscillation between these two "stages" of RF level control (and the dynamic range is stupid wide!).   The preamp 1st stage has about no delay while the 2nd is on a medium-fast timing.

Schematic available if wanted.




Ted
K3RTA

18000km

ronmhauser@...
 

A quick love note for uBitx ... Just worked Andy VK5MAV/6 with my seven watts.  Heard him coming through loud and clear, really excellent receive on this radio.  He is a top notch operator and took my call split in traffic, he is activating some island off the west coast of Australia (OC-211 according to website search). 

He definitely did his part; I have a very quiet listening location; and my antenna is doing most of the work ... but still an exciting QSO to log.

7.005MHz CW, uBitx v5, only mods are RTLSDR tap on 45MHz first IF, and N6DT AGC.  Ant = fixed two element wire beam at 65ft.

73
--Ron
K0EIA

Re: Audio AVC

Jerry Gaffke
 

Ted,

I assume it's this RF Amp from kitsandparts for $12:  http://www.partsandkits.com/rfamp1.3.php
Not a bad idea if you have a compromise antenna such that you don't hear band noise when the antenna
is hooked up to the radio, especially on the upper bands.
Though such an antenna may not be very effective for getting out with the transmitter.

Do you have the ND6T AGC circuit with the added series element: http://www.nd6t.com/uBITX/AGC.htm
 (A kit is available from https://shop.kit-projects.com/ )
Did you find that it didn't have enough dynamic range?

Perhaps you have the earlier ND6T AGC circuit:  http://www.nd6t.com/bitx/AGC
and thus needed the extra AGC circuit.

> The preamp 1st stage has about no delay while the 2nd is on a medium-fast timing.

So "no delay" means very fast attack and very fast decay?
I would not expect that to work very well with an SSB signal.
Did you add an extra LM386 just to sense the audio to drive this extra AGC attenuator?

A schematic would be interesting!

Jerry, KE7ER


On Sun, Apr 21, 2019 at 05:19 AM, Ted wrote:
For what it's worth, I present here the Crowbar Method. It incorporates the best of a quest for maximum sensitivity along with absolute overload protection.  It began when I saw a post here for a sideband RF preamp from partsandkits, an item that I've added to both ubitx projects here.  My first stage of AGC begins with that board.

Re: More Nextion 3.5" tweaks to do

Sam Tedesco
 

Hi Ted,

Joe is actually on the right path. If you look at his pspectrum page pic, he has opened up the vertical lines to extend across the 'black canvas' portion of the page. I looked around and added comments to the code from tmrDisplay so you can get an idea of what Ian is doing. tm0 is going to be a bit more difficult to get going for the graph portion.

sys2=0

if(nBeforeBase.val!=nFreq.val)

{

sys2+=1

}

if(nBeforePos.val!=hViewFreq.val)

{

sys2+=1

}

if(sys2>0)

{

nBeforeBase.val=nFreq.val

nBeforePos.val=hViewFreq.val

fill 0,0,247,52,10565

fill 0,25,247,2,16959 //horizontal line between top boxes

fill 120,10,2,15,16959 //small vertical line top box middle

cov nFreq.val,tmpS.txt,0

xstr 126,4,90,18,0,WHITE,10565,0,1,1,tmpS.txt //top right value

sys0=nFreq.val

sys0=2000*nADCCount.val/2 //2k step fixed

sys0=nFreq.val-sys0

nStartFreq.val=sys0

cov nStartFreq.val,tmpS.txt,0

xstr 2,4,90,18,0,WHITE,10565,0,1,1,tmpS.txt

//fill 0,160,247,20,31727

fill 0,164,247,14,10565 //background of bottom slider

fill 0,173,247,2,16959 //blue line on bottom slider

sys0=hViewFreq.val

sys0=sys0*1000

sys1=sys0+nStartFreq.val

nSelectFreq.val=sys1

cov nSelectFreq.val,tmpS.txt,0

//xstr 150,26,90,24,2,64520,GRAY,2,1,1,tmpS.txt

if(hViewFreq.val>120)

{

xstr hViewFreq.val-92,28,90,24,2,64520,10565,2,1,1,tmpS.txt

}else

{

xstr hViewFreq.val+2,28,90,24,2,64520,10565,0,1,1,tmpS.txt

}

fill hViewFreq.val,0,2,50,64520 //vertical line on top left

fill hViewFreq.val,164,2,14,64520 //small vert slider bottom box

}