Re: Dummy Load Resistors & Motor Oil
I used to have a dummy load of 16 pcs 820 Ohm 2Watt , 5% carbon resistors fitted in parallel in between 2 jam jar lids with this unit inside a syrup tin? . With the tin filled with motor oil the initial resistance was 50.2 Ohm . After more than 10 years it measured 50.6 Ohms ..........probably due to different DVM used.? Hence motor oil is fine. That dummy load would be adequate to test a 100 W- RF transmitter for a few minutes.
Frank? , EI7KS
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Re: No output power on
#v3
Thanks , will try replacing the TDA 2222 and if that doesn't work them will use the LM386 amp
For scratchy audio on a V3, could be in the TDA2822 amp.
An easy way to check this is to take the VOL-M wire from the volume control pot,
detach that wire from the TDA2822 pin 7, then connect that wire plus a ground up
to some other audio amplifer.? This could be the auxiliary input of a hifi stereo,
or it could be an LM386 module such as this:?
? ??
If that sounds good, then the problem is in the TDA2822 stage.
We did have some trouble with the "WX" version of the TDA2822 blowing up:
? ??/g/BITX20/message/64247?p=,,,20,0,0,0::Created,,tda2822+ke7er,20,2,0,29417614
The TDA2822's marked "FCI" pretty much all did fine.
I don't recall reports of bad audio on the TDA2822's, other than no audio after they blew up.
The v4 uBitx with the discrete transistor audio amp did have scratchy audio due to crossover distortion,
if you have a v4 then replacing that part of the circuit with an LM386 module as described above is a good solution.
?
It is possible that your bad audio is in the pre-amp at Q70, or in the demodulator.
But I would try replacing the TDA2822 stage as described above first.
Jerry, KE7ER
On Tue, Nov 3, 2020 at 09:52 AM, rajesh huddar wrote:
The audio is very scratchy on my Ubitx V3.
What needs to be done.
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Re: No output power on
#v3
For scratchy audio on a V3, could be in the TDA2822 amp. An easy way to check this is to take the VOL-M wire from the volume control pot, detach that wire from the TDA2822 pin 7, then connect that wire plus a ground up to some other audio amplifer.? This could be the auxiliary input of a hifi stereo, or it could be an LM386 module such as this:? ? ?? If that sounds good, then the problem is in the TDA2822 stage. We did have some trouble with the "WX" version of the TDA2822 blowing up: ? ?? /g/BITX20/message/64247?p=,,,20,0,0,0::Created,,tda2822+ke7er,20,2,0,29417614The TDA2822's marked "FCI" pretty much all did fine. I don't recall reports of bad audio on the TDA2822's, other than no audio after they blew up. The v4 uBitx with the discrete transistor audio amp did have scratchy audio due to crossover distortion, if you have a v4 then replacing that part of the circuit with an LM386 module as described above is a good solution. ? It is possible that your bad audio is in the pre-amp at Q70, or in the demodulator. But I would try replacing the TDA2822 stage as described above first. Jerry, KE7ER
On Tue, Nov 3, 2020 at 09:52 AM, rajesh huddar wrote:
The audio is very scratchy on my Ubitx V3.
What needs to be done.
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Re: No output power on
#v3
The audio is very scratchy on my Ubitx V3. What needs to be done.
It took me a while to understand it. Basically, as designed, the transistor base to emitter junction And the couple and capacitor form a half wave rectifier power supply. Charging up the coupling capacitor. Until eventually the peak inverse voltage required of the basement or Junction is exceeded, and the transistor is destroyed and the coupling capacitor form a half wave rectifier power supply, driven by a strong RF signal acting like the AC input. Charging up the coupling capacitor. Until eventually the peak inverse voltage required of the base emitter junction (usually only five or six volts) ?is exceeded, and the transistor is destroyed?
Way back in the old days we were all taught how to figure out what reverse voltage capacity is needed by the diode in a half wave power supply
By adding a reverse diode across the base emitter, you stop that power supply effect. ?
Now the coupling capacitor has current moving in both directions, and can¡¯t destroy the transistor?
Gordon ?Gordon, I had read your argument long ago and for some reason I don't remember this point about the C80 charging up.? Good point. Jerry, KE7ER On Mon, Nov 2, 2020 at 10:58 AM, Gordon Gibby wrote:
My previous discussion of the failure mode suggested that it was reverse voltage, as that coupling cap charges up. Having a reverse diode prevents that.
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Looks like a fun project, and I see no reason the approach is wrong.
A few things I'd consider:
Reverse polarity protection:? ?
I'd avoid relays, the cheap ones are prone to failure.? A good solution for very high power but not really needed for a few hundred ma.
A series schottky diode should be sufficient, perhaps the PFET solution if you really care about conserving the last few mWh from your battery.
Fuses are always a good idea, though a polyswitch with an LED indicator across it might work well here
A 0.5A fuse (or polyswitch) into the main board with a separate 2A fuse for the IRF510's would be my preferred solution.
The ADS1115 have 4 ADC channels of 16 bits each which could be useful, but keep in mind
that the sample rate is limited to below 1khz whereas STM32F uC's have 12bit ADC's good to 1mhz or so.
I'd consider a uC in a QFP48 package rather than choosing a module such as the ESP32, could be much smaller.
Though I don't know exactly what resources on the ESP32 you might be planning to use.
The class D audio amp will have some RF switching noise at the speaker output,
will needs some very effective RF bypass caps, and perhaps some shielding.
Having AGC in the same package is convenient, though attenuating RF instead of audio will allow
much more dynamic range since high signal levels can overload the audio pre-amp at Q70.
Asking for several watts at 5V means you may want something more efficient than a 5v linear regulator.
The LM386 is extremely old and has a fair bit of distortion, but it does work directly from 12vdc
and doesn't have the switching noise of a class D amp..
The S-meter sensor should be simple enough that a separate module would not be required,
this is often derived from the detected signal for AGC action.
Regardless, looks like a fun project.
This is the stage at which you want to carefully consider alternatives,
as it's much easier to change things than it is after you have fabricated the board.
?
Jerry, KE7ER
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Show quoted text
On Tue, Nov 3, 2020 at 05:24 AM, <ramonlh@...> wrote:
Hola,
I am working on version 3 of Raduino32. The idea is to unplug the Arduino Nano and directly plug in Raduino32 and have modules that can be easily plugged in.
So far, the modules that can be connected are:
- ESP32 to replace the Arduino Nano.
- 2 x ADS1115 modules. They read up to 8 analog values ??(S-meter, v-For, V-Ref, Amp, etc)
- Current sensor ACS712.
-TDA2016D2 Adafruit module. 2-channel audio amplifier controlled by I2C with AGC.
- S-meter sensor module.
- Polarity protection module with relay or Mosfet IRPF9540.
Connections for:
- SWR sensor
- DS18B20 temperature sensors for power transistors and 5v regulator.
- 2 x servomotor to control an Emtech ZM-2 coupler.
Connections with uBitx:
- Audio 8 pins.
- CW1
- CW2
- Speaker
- Ant
- P1
I attach the diagrams for Raduino32, S-meter sensor and Polarity Protection.
?
Any suggestion is welcome.
Ram¨®n, EA4GZI
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Hola, I am working on version 3 of Raduino32. The idea is to unplug the Arduino Nano and directly plug in Raduino32 and have modules that can be easily plugged in.
So far, the modules that can be connected are:
- ESP32 to replace the Arduino Nano.
- 2 x ADS1115 modules. They read up to 8 analog values ??(S-meter, v-For, V-Ref, Amp, etc)
- Current sensor ACS712.
-TDA2016D2 Adafruit module. 2-channel audio amplifier controlled by I2C with AGC.
- S-meter sensor module.
- Polarity protection module with relay or Mosfet IRPF9540.
Connections for:
- SWR sensor
- DS18B20 temperature sensors for power transistors and 5v regulator.
- 2 x servomotor to control an Emtech ZM-2 coupler.
Connections with uBitx:
- Audio 8 pins.
- CW1
- CW2
- Speaker
- Ant
- P1
I attach the diagrams for Raduino32, S-meter sensor and Polarity Protection.
?
Any suggestion is welcome.
Ram¨®n, EA4GZI
 
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Just got this about the dummy load kit, check out the link to see if it is what you want. You cana;do go to this website for a discussion on how to use the dummy load for finding power level...
Here is the response I got from him. This website offers many Kenwood related items, including some relays:
Hello Bob,
Yes we do.? You can find them here:
Thanks for your interest.
Best Regards,
Barb Kemski
Bob ¡ª KK5R
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Yep!
And in the drains it helps keep bugs out (they can swim through water just fine, but will drown in the oil.)
Cheers.
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Re: Dummy Load Resistors & Motor Oil
Hi,
The standard is mineral oil.? Easily available at the drug store as it's used as a laxative.? Veterinarian supply places should have it available in large quantities.
Oil for modern vehicles is about 1/3 additives; things that are probably not suited for a dummy load.
You can buy non-detergent motor oil which would be pure oil.? But it does kind of smell.? As would any vegetable oil after a long time (they go rancid).
Cheers,? ?Mark
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Re: No output power on
#v3
It took me a while to understand it. Basically, as designed, the transistor base to emitter junction And the couple and capacitor form a half wave rectifier power supply. Charging up the coupling capacitor. Until eventually the peak inverse voltage required of the basement or Junction is exceeded, and the transistor is destroyed and the coupling capacitor form a half wave rectifier power supply, driven by a strong RF signal acting like the AC input. Charging up the coupling capacitor. Until eventually the peak inverse voltage required of the base emitter junction (usually only five or six volts) ?is exceeded, and the transistor is destroyed?
Way back in the old days we were all taught how to figure out what reverse voltage capacity is needed by the diode in a half wave power supply
By adding a reverse diode across the base emitter, you stop that power supply effect. ?
Now the coupling capacitor has current moving in both directions, and can¡¯t destroy the transistor?
Gordon
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Show quoted text
On Nov 2, 2020, at 15:26, Jerry Gaffke via groups.io <jgaffke@...> wrote:
?Gordon, I had read your argument long ago and for some reason I don't remember this point about the C80 charging up.? Good point. Jerry, KE7ER On Mon, Nov 2, 2020 at 10:58 AM, Gordon Gibby wrote:
My previous discussion of the failure mode suggested that it was reverse voltage, as that coupling cap charges up. Having a reverse diode prevents that.
|
Re: No output power on
#v3
Gordon, I had read your argument long ago and for some reason I don't remember
this point about the C80 charging up.? Good point.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 10:58 AM, Gordon Gibby wrote:
My previous discussion of the failure mode suggested that it was reverse voltage, as that coupling cap charges up. Having a reverse diode prevents that.
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Re: Screen model. Explaim me
Evan, Yeah, I know that.Here, the idea is to connect a different screen of the famous ILI9341 and use the new menus of the V6 version with.Imagine the opposite, the Ubitx V6 could have been planned with a different screen than the ILI9341. In this case, we could have looked at how to modify and put an ILI9341.I think we¡¯re not far away.?The connection seems possible, the app will require some changes.I think there will be modifs of code to do on V6 version.
look here in the code of the v6 version:..
The model is called tjctm24028-spi
it uses an ILI9341 display controller and an? XPT2046 touch controller.
*/
//XPT2046_Touchscreen ts(CS_PIN);
a programmer can help us
cdt
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Re: No output power on
#v3
All of the receiver front end protection that I found on the net used two diodes as I had them configured.? The worst case I believe is that the second diode would be redundant and the best would provide the symmetrical signal clipping.? The one improvement is to add the 6.3-volt incandescent lamp to dissipate the energy between the two relays.
73
Evan
AC9TU
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Re: No output power on
#v3
I really didn¡¯t use mine an awful lot after I installed one diode, but I never ever had a Q90 go bad.
My previous discussion of the failure mode suggested that it was reverse voltage, as that coupling cap charges up. Having a reverse diode prevents that.
There¡¯s nothing terribly wrong with having two ; it just may raise other issues that I never thought through.
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On Nov 2, 2020, at 13:25, Jerry Gaffke via groups.io <jgaffke@...> wrote:
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Re: Screen model. Explaim me
On Mon, Nov 2, 2020 at 10:21 AM, Gerard wrote:
Yes, I understood, but from what I read KD8CEC did not write a soft for the V6.
Gerard, The v5 software works with the v6 boards.? The only difference is the connections to the Raduino change.? Since you do not have the Raduino board, the Nano and Si5351 are mounted to your mainboard, That does not make any difference.? For your current setup, after you change the SSB filter to 11.059 Crystals, you need only change the Nano program to the vUBITX5 program with the _NX at the end. UBITXV5_CEC_V1.200_NX.hex 73 Evan AC9TU
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Re: No output power on
#v3
I think two diodes should work fine.
Gordon is saying that one diode might be sufficient,?
since the base-emitter junction of Q90 can work as the second diode.
He could be right.
Though that 2n3904 base-emitter junction is rather wimpy,
and an asymetrical signal may be worse than clipping top and bottom equally.
The AC coupling into the Q90 base also complicates things.
Not obvious to me what's best.
Jerry, KE7ER
On Mon, Nov 2, 2020 at 09:23 AM, Kit Peters wrote:
I was going off of Evan Hand's mod ( /g/BITX20/message/83186) which has two diodes, one opposite the other, across two of the pins on K1.
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Re: Screen model. Explaim me
I forgot to specify, on this example it is an arduino uno (D7 D13), on the Ubitx, those are the same connections on the Nano with are used. (D8---D13)
only D7 to add
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Re: Screen model. Explaim me
Hello, see beginning of the post Do you thing my QVT will work with these connexions and compiling a version of UBITX with adding the XPT2046 files in Arduino schema? An expert programming may be answered. Connetings seem to be the same with ili9341 (see Excel files), only DB7 in sus No sure for the VCC +5, to see. Smoke or no smoke, that is the question? LOL it's testing for fun, my TFT cost 10€ cdt 
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Re: No output power on
#v3
I was going off of Evan Hand's mod ( /g/BITX20/message/83186) which has two diodes, one opposite the other, across two of the pins on K1.
The only diode needed on Q90 is one to prevent reverse voltage damage. ?? ? oh, and I removed the diodes.
On Mon, Nov 2, 2020 at 10:58 AM Kit Peters < popefelix@...> wrote: I'll check all that, thanks.
As for test equipment, I have both a DMM and an old oscilloscope.
Kit,
I would expect a transmission of 15W a short distance away to create a very strong signal in an unshielded uBitx.
Perhaps you also have a problem in receive, but for now I will assume that is not the case.
The fact that you receive any signal at all with the uBitx tuned to display the same frequency as your transmitter
suggests the receiver is mostly working.? You may have trouble where the diodes were added if that was done incorrectly.
I would suggest not doing mods until everything the stock rig is working properly.
When debugging the transmitter, I would start with CW mode as Even suggested in post 83195:
>? Verify the transmit power using CW, not SSB.
There is a lot less to go wrong when transmitting in CW mode.
Put a good dummy load on the antenna terminal, put the uBitx in CW mode,?
and press the CW key to transmit.? The DC voltage on both ends of R84 should be 12 volts
when transmitting, and PA-PWR into L9 should also be 12 volts DC.
Put your finger on the IRF510 heatsinks and the dummy load occasionally,
let up on the key for a few minutes if they get too warm.
Put a 6" piece of wire on the base of Q90 as an antenna, see if you can hear the transmit
signal on a nearby receiver when you hold the key down.
If the above steps check out, take DC voltage readings for the stages from Q90
on out through the IRF510's, compare to those on pages 13, 14, and 15 of this document:
? ?
That is a fairly complete debug guide for the v3 uBitx.
Let us know how far you get.? If you need further help, let us know what
instruments you have available.? I assume you have a DVM.
Do you have access to a diode RF probe, or better yet an oscilloscope?
Good luck, this may prove to be educational.
If you can get help from a ham at a nearby club who has a bench full of instruments
and experience with troublshooting, that would help this process considerably.
Jerry, KE7ER
On Mon, Nov 2, 2020 at 07:20 AM, Kit Peters wrote:
I haven't dug into this in depth, but I did test receive last night. Pumping 15 W into my loop with a borrowed Kenwood TS-2000 I was able to (faintly) hear my transmission in a dummy load. I suppose I could have stuck a piece of wire into a UHF connector and made a quickie vertical as well, but that was what occurred to me at the time. :)
--
Kit Peters, W0KEH GPG public key fingerpint:? D4FF AA62 AFEA 83D6 CC98 ACE5 6FAE 7E74 7F56 ED1DHello to any and all NSA, DEA, or other government or non-government agents reading this email.? Tell me about your life; I'll tell you about mine.
-- Kit Peters, W0KEH GPG public key fingerpint:? D4FF AA62 AFEA 83D6 CC98 ACE5 6FAE 7E74 7F56 ED1DHello to any and all NSA, DEA, or other government or non-government agents reading this email.? Tell me about your life; I'll tell you about mine.
-- Kit Peters, W0KEH GPG public key fingerpint:? D4FF AA62 AFEA 83D6 CC98 ACE5 6FAE 7E74 7F56 ED1DHello to any and all NSA, DEA, or other government or non-government agents reading this email.? Tell me about your life; I'll tell you about mine.
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Re: No output power on
#v3
The only diode needed on Q90 is one to prevent reverse voltage damage. ??
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Show quoted text
On Nov 2, 2020, at 11:59, Kit Peters <popefelix@...> wrote:
? oh, and I removed the diodes.
On Mon, Nov 2, 2020 at 10:58 AM Kit Peters < popefelix@...> wrote: I'll check all that, thanks.
As for test equipment, I have both a DMM and an old oscilloscope.
Kit,
I would expect a transmission of 15W a short distance away to create a very strong signal in an unshielded uBitx.
Perhaps you also have a problem in receive, but for now I will assume that is not the case.
The fact that you receive any signal at all with the uBitx tuned to display the same frequency as your transmitter
suggests the receiver is mostly working.? You may have trouble where the diodes were added if that was done incorrectly.
I would suggest not doing mods until everything the stock rig is working properly.
When debugging the transmitter, I would start with CW mode as Even suggested in post 83195:
>? Verify the transmit power using CW, not SSB.
There is a lot less to go wrong when transmitting in CW mode.
Put a good dummy load on the antenna terminal, put the uBitx in CW mode,?
and press the CW key to transmit.? The DC voltage on both ends of R84 should be 12 volts
when transmitting, and PA-PWR into L9 should also be 12 volts DC.
Put your finger on the IRF510 heatsinks and the dummy load occasionally,
let up on the key for a few minutes if they get too warm.
Put a 6" piece of wire on the base of Q90 as an antenna, see if you can hear the transmit
signal on a nearby receiver when you hold the key down.
If the above steps check out, take DC voltage readings for the stages from Q90
on out through the IRF510's, compare to those on pages 13, 14, and 15 of this document:
? ?
That is a fairly complete debug guide for the v3 uBitx.
Let us know how far you get.? If you need further help, let us know what
instruments you have available.? I assume you have a DVM.
Do you have access to a diode RF probe, or better yet an oscilloscope?
Good luck, this may prove to be educational.
If you can get help from a ham at a nearby club who has a bench full of instruments
and experience with troublshooting, that would help this process considerably.
Jerry, KE7ER
On Mon, Nov 2, 2020 at 07:20 AM, Kit Peters wrote:
I haven't dug into this in depth, but I did test receive last night. Pumping 15 W into my loop with a borrowed Kenwood TS-2000 I was able to (faintly) hear my transmission in a dummy load. I suppose I could have stuck a piece of wire into a UHF connector and made a quickie vertical as well, but that was what occurred to me at the time. :)
--
Kit Peters, W0KEH GPG public key fingerpint:? D4FF AA62 AFEA 83D6 CC98 ACE5 6FAE 7E74 7F56 ED1DHello to any and all NSA, DEA, or other government or non-government agents reading this email.? Tell me about your life; I'll tell you about mine.
-- Kit Peters, W0KEH GPG public key fingerpint:? D4FF AA62 AFEA 83D6 CC98 ACE5 6FAE 7E74 7F56 ED1DHello to any and all NSA, DEA, or other government or non-government agents reading this email.? Tell me about your life; I'll tell you about mine.
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rajesh huddar
Bob Lunsford
Gerard
Aurelia Fenderson-Peters