Date   
Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

Do not place that capacitor from Q1 base to emitter. That will make a dandy blocking oscillator. Pin 7 of U1 already has a bypass (C78). It's just not shown on the schematic. Rather try hanging a big electrolytic across 5 volts to ground. Something like 100 uF, or 1,000 uF. in addition to a 10 nF (.01 uF). I haven't had to use any filtering on 5 volts other than the 1uF which is already on the Raduino. But my uBITX has a 1000 uF. on the 12 volt lead to the big board and the Raduino. I'm pretty sure that's why I have no issues. -Don

RFI problem at the encoder switch #ubitx-help

hakan.sjostrom@...
 

As soon as I speak in the microphone the display switches to "Band Select?". Both on a EFHW and a dipole antenna with low SWR. Except building RF chokes is there anything else worth trying - like a capacitor? Or a shielded wire from the encoder switch?

Re: RFI problem at the encoder switch #ubitx-help

Gordon Gibby
 

That is classic radio frequency interference. I’ve seen it in my own unit—-, so start shielding and bypassing and keep it up, until you get it stopped.

Folks who do digital communications get real good at this kind of stuff because any radio frequency interference at all and they have real problems.  You can do it too!


On Jul 1, 2018, at 13:47, "hakan.sjostrom@..." <hakan.sjostrom@...> wrote:

As soon as I speak in the microphone the display switches to "Band Select?". Both on a EFHW and a dipole antenna with low SWR. Except building RF chokes is there anything else worth trying - like a capacitor? Or a shielded wire from the encoder switch?

Re: Ubitx and QRP Guys Multi Z Tuner #ubitx-help

Doug W
 

double check you have a 4.7k resistor across Radiuno pins 2 & 3 and recheck all your ground connections
--
www.bitxmap.com

Re: RFI problem at the encoder switch #ubitx-help

hakan.sjostrom@...
 

Thanks Gordon, I've been looking around for this problem and just when I posted this I saw a similar posting from Gwen Patton just here !!
OK, I will start shielding and bypassing :-)

#uBITX #ubitx

SM6MOJ
 

Two capacitors -C210 and C216- arr missing from my uBITX motherboard.
Also, when I connect the board to 12V, the book says that the current
drain should be 100mW. But there is no current drain att all.

Can I assume that the board is fault?

Re: #uBITX #ubitx

Michael Shreeve
 

I looked at the V4 schematic and the value for both of those caps is zero. This means there are no caps installed. V3 has the same lack of capacitors. So, he isn't using them. 

On Sun, Jul 1, 2018 at 11:07 AM, SM6MOJ <andrew@...> wrote:
Two capacitors -C210 and C216- arr missing from my uBITX motherboard.
Also, when I connect the board to 12V, the book says that the current
drain should be 100mW. But there is no current drain att all.

Can I assume that the board is fault?










--
Michael Shreeve N6GRG

Re: #uBITX #ubitx

Michael Shreeve
 

Are you getting audio from the board ?

On Sun, Jul 1, 2018 at 11:54 AM, Michael Shreeve <shreevester@...> wrote:
I looked at the V4 schematic and the value for both of those caps is zero. This means there are no caps installed. V3 has the same lack of capacitors. So, he isn't using them. 

On Sun, Jul 1, 2018 at 11:07 AM, SM6MOJ <andrew@...> wrote:
Two capacitors -C210 and C216- arr missing from my uBITX motherboard.
Also, when I connect the board to 12V, the book says that the current
drain should be 100mW. But there is no current drain att all.

Can I assume that the board is fault?










--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG

Re: RFI from uBitx TX after AGC and other mods installed

Rick Price
 

John, Don Lawrence, others
Interesting Outcome! Shielding was no help, replacing pcb with perfboard agc helped a little, but back to pcb. bypass's on 78L05 were .68 on input and .1 on output still no help and removed 78Ll05. Did not try 1nf,10nf,100nf in parallel on 78L05 because I had already removed it.  Because pin 7 of U1 (TDA2822) is already bypassed with C78 did not do. Don suggested to filter the 5v supply. I get the 5 volts from the radino pin 3 (green wire) and use it for both AGC and mike preamp. Used a 470uf and .01 on the 5V no improvement.  Don suggested not to try the emitter-base capacitor because of forming a blocking oscillator. It looked to me that because the emitter was already grounded that it probably just bypass any unwanted signal to ground and not oscillate, connecting to the collector might have been another story.. What the heck nothing ventured nothing gained. Tried the .01 and turned on expecting possible oscillations of some sort. AGC off transmitting nothing as before, AGC on transmitting at full volume only occasionally get a very small occasional hint of audio coming through the speaker no oscillations of any kind. Before as soon as audio was present from the mike it started coming through and sometimes went into oscillations.  Hardly ever run at full volume so it looks like your theory and suggestion Lawrence may work. ARC still appears to work as before but will need a strong signal to verify.  Still have to experiment with a couple of different values to see what's best. Hope this spells relief with the agc on for the few of this it affects. Thanks to all for the input and suggestions.
 
Rick 
KN4AIE 



From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Lawrence Galea
Sent: Sunday, July 01, 2018 12:28 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI from uBitx TX after AGC and other mods installed

Also try putting a 100n directly across Q1 base-emitter on the AGC board.
It will cut off some of the higher AF as it would be in series with C1 to earth across the Af gain control.  
However, this would not be of any serious consequences.
If you don't want as much AF HF cut off you can try a smaller capacitor, say 10n.
I am thinking that Q1 base-emitter junction is acting as a detector and the AF is being coupled back to the AF gain control since the level is varying with the AF Gain control.
One could also add say a 10n capacitor directly on pin 7 of the TDA2822 or across the AF Gain control as an rf decoupling.
Can you try and report?


On Sun, Jul 1, 2018 at 5:33 PM, Lawrence Galea <9h1avlaw@...> wrote:
Did you put 100n, 10n, 1n filter capacitors  all in parallel on both input and output directly across the 78L05 leads?
.


On Sun, Jul 1, 2018 at 2:31 PM, Rick Price <rickprice48@...> wrote:
John, Don, others,
Yesterday I attached a 78L05 (TO220) directly to the back of the AGC board that is mounted to the RF gain control on the front panel. Bypassed all power leads and ran a separate power lead to the 12V regulator that powers my uBitx. In other words the AGC board had its own isolated(?) power source. Stll heard the audio when transmitting.  Beginning to think that radiated power is being absorbed by the AGC board and then recitifed and then coupled into the audio system. I also have the pop click board installed and not sure if this was a problem before it was installed. My AGC board is one I fabricated using Don's technique of cutting pcb with an x-acto knife.  I also have a AGC board made on perf board using through hole parts.  May sub that in and see if there are any changes. I eventually plan on installing the JackAl mod when it becomes available so this problem should go away for me but its beginning to become a challenge to fix.
 
Rick KN4AIE


From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of John KC9OJV
Sent: Sunday, July 01, 2018 8:05 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI from uBitx TX after AGC and other mods installed

Don,
I spent part of yesterday applying ferrites to this and that to little success. I also tried wrapping the 5v line around the twisted pair coming from the volume pot and that did some good. This morning I was thinking about fixing a 7805 to the metal base of my case, drilling a hole in the ground plane and routing a wire through that hole to feed the AGC board. It could be driven off the 12v relay (K1?). Has anyone else had any ideas/success?

John
KC9OJV



Re: BITX QSO Afternoon/Evening, Sunday, July 1, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

John P
 

I'm calling CQ on 7277. Hearing nuttin but noise!
--
John - WA2FZW

newbee here...just made the order...antenna question on old G5RV

Don - KM4UDX
 

Finally, after a year or more of hand ringing and second guessing myself, I finally pulled the switch and ordered my uBITX! 

 

Believe it or not, it came down to the ICOM7300 or the uBITX.  I picked the uBITX because I love to solder and build, and when things are hard, they are much more satisfying when you finally get over the hill.  And what I learn with the uBITX will apply to any more complex and capable transceiver downstream. So I pulled the plug.  Should start the build in a few weeks. Also ordered the normal white plastic case from BG, and bnc to SO239 connectors, etc.

 

Questions to the wise ones: Can I hook up the uBITX my G5RV? I have a length of coax (which has a simple choke) that connects to the twinlead, which then goes to the dipole aerial WITHOUT an antenna tuner?

 

I borrowed 100W transceiver, and the G5RV worked just fine. But the 100W rig had an internal antenna turner, which I’m told the G5RV needs.  The uBITX does not have a antenna tuner…will it work well enough directly connected with the G5RV?

 

If I have to get an antenna tuner…(rats!), then I’m thinking of the ZM-2 or the like.

https://steadynet.com/emtech/zm2-kit-uhf-connectors

 

Guidance please!

 

Thank you o wise ones!

 

Don

KM4UDX

 

 

 

From: John P
Sent: Sunday, July 1, 2018 3:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BITX QSO Afternoon/Evening, Sunday, July 1, 3PM & 7PMLocal Time, 7277 kHz in North America, 7177 kHz elsewhere.

 

I'm calling CQ on 7277. Hearing nuttin but noise!

--
John - WA2FZW

 

Re: RFI from uBitx TX after AGC and other mods installed

John KC9OJV
 

Thanks Rick- ditto on the electrolytic. I tried a 1000uF 16v electrolytic at the board and didn't notice any effect at all.

John
KC9OJV

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

Thank you!! I tried that TWICE and got this screaming tone. Perhaps the third time is in order. I wonder sometimes if I am living in an alternative universe. Goes to show that you should always question the "experts". Thank you very much for hanging in there, Rick. Good suggestion Lawrence. 73, Don

Re: RFI from uBitx TX after AGC and other mods installed

Rick Price
 

Don, please don't think I was questioning the experts, just was running out of options, suggestions, and like I said nothing ventured nothing gained and had tried everything else. Will always take advice from those that have been there before! Thanks again,
 
Rick

 


From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Don, ND6T via Groups.Io
Sent: Sunday, July 01, 2018 3:56 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI from uBitx TX after AGC and other mods installed

Thank you!! I tried that TWICE and got this screaming tone. Perhaps the third time is in order. I wonder sometimes if I am living in an alternative universe. Goes to show that you should always question the "experts". Thank you very much for hanging in there, Rick. Good suggestion Lawrence. 73, Don

Re: newbee here...just made the order...antenna question on old G5RV

Jerry Gaffke
 

You wanted wise ones, but I'll jump in till one shows up.

The uBitx will want to see 50 ohms, ideally under a 2 to 1 SWR, though I suspect it will
survive most anything if you power the IRF510's from not much beyond 12v.

The G5RV antenna is not resonant, the impedance it presents will be all over the map.
You really need a tuner between it and the 50 ohm coax to the uBitx.

That ZM-2 might be sufficient, I don't really know.


The fact that you cannot adjust inductance is not a plus in my book, that could be getting 
inefficient as frequencies go up and capacitive coupling between windings gets out of hand.
It claims to be good to 15 Watts, though does not really say under what conditions that might be true.
Max power it can handle will vary considerably with operating frequency and antenna impedance.

I'm happy enough with my MFJ-949E tuner/swr/dummyload
Build quality varies on the MFJ stuff, you want to lift the lid when you get it and check the solder job.

If you want to build your own tuner, you need an SWR indicator such as Diz's Tandem Match SWR indicator:
    http://www.kitsandparts.com/bridge1.4.php
Generally the tuner itself can be a couple tuning caps from some old tube type broadcast receiver
and a hand wound inductor with an alligator clip to tap into it somewhere, check the various handbooks on that.

For the price of the 7300, you can have a half dozen uBitx's go up in flames
and try out several MFJ tuners plus some homemade ones. 
And learn an awful lot in the process.

Jerry, KE7ER


On Sun, Jul 1, 2018 at 12:32 pm, Don - KM4UDX wrote:

Finally, after a year or more of hand ringing and second guessing myself, I finally pulled the switch and ordered my uBITX! 

 

Believe it or not, it came down to the ICOM7300 or the uBITX.  I picked the uBITX because I love to solder and build, and when things are hard, they are much more satisfying when you finally get over the hill.  And what I learn with the uBITX will apply to any more complex and capable transceiver downstream. So I pulled the plug.  Should start the build in a few weeks. Also ordered the normal white plastic case from BG, and bnc to SO239 connectors, etc.

 

Questions to the wise ones: Can I hook up the uBITX my G5RV? I have a length of coax (which has a simple choke) that connects to the twinlead, which then goes to the dipole aerial WITHOUT an antenna tuner?

 

I borrowed 100W transceiver, and the G5RV worked just fine. But the 100W rig had an internal antenna turner, which I’m told the G5RV needs.  The uBITX does not have a antenna tuner…will it work well enough directly connected with the G5RV?

 

If I have to get an antenna tuner…(rats!), then I’m thinking of the ZM-2 or the like.

https://steadynet.com/emtech/zm2-kit-uhf-connectors

 

Guidance please!

 

Thank you o wise ones!

 

Don

KM4UDX

Re: #uBITX #ubitx

SM6MOJ
 

Dear Michael

Thank you for your wise words. Now all I have to do is work out why there
is no current drain.

Andrew

Re: #uBITX #ubitx

Lowell Haney NE4EB
 

If there is no current drain, what shows up on the LCD? Is the back light lit?

What method are you using to measure the current draw?

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

Rick, I'm saying that you really SHOULD! A little history: I originally had a .01 uF across the input audio and well, surprise! Then Kees slipped it in on his re-make so I tried again with the same result. I sure hope that it helps Rowland, Alan, Mark and the rest. I'll try again and include that in the web pages. 73, Don

Re: BITX QSO Afternoon/Evening, Sunday, July 1, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

kc1at
 

calling also but nothing heard. This week unlike the last 2 weeks I have my antenna connected. Don't ask.

don, still listening

Re: newbee here...just made the order...antenna question on old G5RV

Ralph Mowery
 

With almost any antenna designed to work over a large frequency range you will need a tuner of some sort.  Either a built in one or external.
The G5RV is not really that good of an antenna for all bands.  It was designed for 20 meters and a certain pattern.  It will give a reasonable SWR over many of the ham bands, but still a tuner is needed.  I like an off center fed antenna for working most ham bands .  It still needs an antenna tuner.  Look for the plans of a Carolina Windom if you want to build one.

As you are going to need a SWR bridge I wold look at a tuner that has a SWR meter built in.  Much as I hate say it about getting a MFJ, that may be the best for the dollar.  Open it up and check for loose parts and bad solder connections.  Lots of the mfj stuff seems to be about 99% built. and you need the extra 1%.
LDG makes some good automatic tuners at a reasonable price.

73 de ku4pt





On Sun, Jul 1, 2018 at 3:32 PM, Don - KM4UDX <dontAy155@...> wrote:

Finally, after a year or more of hand ringing and second guessing myself, I finally pulled the switch and ordered my uBITX! 

 

Believe it or not, it came down to the ICOM7300 or the uBITX.  I picked the uBITX because I love to solder and build, and when things are hard, they are much more satisfying when you finally get over the hill.  And what I learn with the uBITX will apply to any more complex and capable transceiver downstream. So I pulled the plug.  Should start the build in a few weeks. Also ordered the normal white plastic case from BG, and bnc to SO239 connectors, etc.

 

Questions to the wise ones: Can I hook up the uBITX my G5RV? I have a length of coax (which has a simple choke) that connects to the twinlead, which then goes to the dipole aerial WITHOUT an antenna tuner?

 

I borrowed 100W transceiver, and the G5RV worked just fine. But the 100W rig had an internal antenna turner, which I’m told the G5RV needs.  The uBITX does not have a antenna tuner…will it work well enough directly connected with the G5RV?

 

If I have to get an antenna tuner…(rats!), then I’m thinking of the ZM-2 or the like.

https://steadynet.com/emtech/zm2-kit-uhf-connectors

 

Guidance please!

 

Thank you o wise ones!

 

Don

KM4UDX