Wrong links in daily summary
I switched yesterday to the daily summary option for receiving group information - and as soon as the first message arrived I found that all the links contain an error, e.g.:
- the "https//" is not necessary and makes the link unusable. Is it groups.io or the BitX20 group issue?
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73,
Greg DL3GJ FISTS #17694 / SKCC # 15874 / GQRP #15403
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Re: Possible PA low output problem. Problem SOLVED
I had wierd problems and instability.
My 40M antenna unused for a long time was showing high SWR - a new Balun
fixed that issue. But not the power and instability in the IRF.
Finally figured out it was a bad cable that I had soldered from ant
output to a BNC linked to my antenna. This cost me an IRF!
That was that and the rig works beautifully as intended by
Farhan!
Never assume what LOOKS ok is OK but it may not be OK like my
case!!
Cheers
Raj
At 10/02/2017, you wrote:
toggle quoted message
Show quoted text
Don't assume low power out is
due to a bad diode pair.
The two issues at Q13 mentioned below can both cause a "Possible PA
low output problem" that would be indistinguishable from a bad diode
pair in the modulator.? Also could be a a damaged IRF510, perhaps
from driving a high SWR load with 20v on the drain, or setting the bias
control beyond 100ma quiescent.? Or the microphone connector got
shorted out.? Or transformer wires shorted or broken.? Or about
half the remaining parts in the rig experiencing some sort of
failure.
On Thu, Feb 9, 2017 at 12:19 pm, Jerry Gaffke wrote:
- Regarding post 19730, there's a couple issues a bit further down that
we need to keep track of.
- 1)? Q13 is dissipating an awful lot of heat for a Sot23, may
need to adjust the emitter resistor there.
- 2)? Having your Bitx40 hooked up to an antenna while some nearby
antenna is transmitting at high power can blow Q13, may need Raj's dual
diode plus lamp fix.
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Re: Possible PA low output problem. Problem SOLVED
Jerry, I am back at the farm this week. Counting the days to Monday so I
can be reunited with my pup and Bitx40!!
I have received some 3904 SMTs, I propose to put one parallel on top of
the existing Q13 and see how much that helps!
I found an old commercial Motorola Mic in my junk. Just 4 wires and seems
perfectly suited to this board. These mics
have built in mic preamp and thats helping me drive the final amp crazy!
The IRF draws more than 1 amp and power meter
is showing 10W. Must be distorting but I did not have time to check with
scope. Plan to have a QSO with vu2pop
for a critical report on audio etc. this coming week.
The mic seems something like this but the model number is worn out.
I still on analog VFO and it's holding 10-20Hz drift.
Cheers
Raj
At 10/02/2017, you wrote:
toggle quoted message
Show quoted text
Regarding post 19730, there's a
couple issues a bit further down that we need to keep track of.
1)? Q13 is dissipating an awful lot of heat for a Sot23, may need to
adjust the emitter resistor there.
2)? Having your Bitx40 hooked up to an antenna while some nearby
antenna is transmitting at high power can blow Q13, may need Raj's dual
diode plus lamp fix.
On Thu, Feb 9, 2017 at 12:04 pm, Jerry Gaffke wrote:
- post 19730
?
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Re: Possible PA low output problem. Problem SOLVED
What BITX40 needs is a BAT54S - this version has two diodes in opposite
direction. Anode of one connected to cathode of the other.
Marking may be KL4.. or Vishay L44.. or even ?V4
As some one reported IL440 - looks like Vishay, the extra letters and
digits I and 0 may refer to some manufacture details!
Raj
At 10/02/2017, you wrote:
toggle quoted message
Show quoted text
You'll never see BAT54 printed
on a SOT23, that wouldn't fit.? So they choose an arbitrary 2 or
3? character code to distinguish it from all the other SOT23
products they make.? But there are far more SOT23 types than there
are codes, and different manufacturers that build BAT54's will choose
different codes.? We've seen this before on the 2n3904 transistors,
read post 19730.? The ohmmeter readings taken of the bad part
suggest that it really is a dual diode.
My guess is that the correct part is getting stuffed, but at least one
slipped by QC at the factory, got damaged when soldering it down, or by
excessive current now that the 100 ohm pot has been removed.? If it
is excessive current, perhaps adding a resistor in series with C106 would
fix it.? Adding back R106 if it isn't needed for establishing
modulator balance would best be avoided.? Not yet clear if this dual
diode was a problem on more than one unit.
Jerry, KE7ER
On Thu, Feb 9, 2017 at 11:23 am, John Smith wrote:
- I haven't seen anything marked BAT54.
?
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Re: Possible PA low output problem. Problem SOLVED
My DDS BITX40 is now putting out over 5 watts. 1. Ripped out the double diode. 2. Attached 2x ?1N4148 ?diodes (any 2) with the ring ends connected to the empty solder spots for the right orientation. 3. Joined the other ends of the diodes together and soldered them into the empty hole for the missing trimpot ? ?- centre pin hole. 4. Wound the PA bias trimpot to fully clockwise. ?Adjusted slowly to fully anticlockwise and got 0.9A ?with? ? ?no modulation. ?Speaking very loudly, output watt meter on ATU jumping between 5 and 7 watts into dummy load. That's it. ?No more no less Cheers - ?Noel
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Re: transmitting CW with Raduino Bitx40?
Al, In the Tips n Mods pdf in the first folder in the files section is the wiring colours and their use with the extra code.? It's worth downloading as there's plenty of stuff taken from all the posts since the BitX40 started. ?? In case you don't want to, it's as follows :-
It uses a pushbutton on A3 pin to select
using tap, press, double tap method. Wiring colours used are Brown = CW??
Key ? Red? =
Calibrate and CW tone when in CW Orange = Pushbutton to select Dual
vfo¡¯s,? RIT,? CW Blue = PTT Sense Black = LPF Select ¨C not catered for yet
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Rob G4NQX
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Re: Raduino USB connector
Make sure your problem isn't caused by the metal fingers in the mini-USB socket. See my post? /g/BITX20/topic/if_raduino_programming_cable/4334102?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,40,4334102?? 73 AL
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Has anyone experienced a problem finding a suitable USB cable for the Raduino? I have several cables here with me and none of them fit. I have more at home but won't be there for another couple of months.
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Re: 80 M and Shortwave receive to BITX40v3 (Non digital vfo )
There are some great beginning C books for Arduino...ahem...
Jack, W8TEE
From: vk3xl via Groups.Io <vk3xl@...>
To: [email protected]
Sent: Thursday, February 9, 2017 10:44 PM
Subject: Re: [BITX20] 80 M and Shortwave receive to BITX40v3 (Non digital vfo )
This is great news. I have 2 BitX40 boards one I want to convert to 80 meters. Thanks for doing the ground work for me. Now to learn about arduino programing.....?
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Mike VK3XL
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Hi Bob
The VFO signal must be approx. 1.4 volts peak to peak at T2 input.
73
Ken VA3ABN
On Thu, Feb 9, 2017 at 10:32 PM, bob.mix@... <bob.mix@...> wrote: I finally bit the bullet in my BitX40 by removing L4 to try my own VFO.?
The original radio worked and I heard many CW and SSB stations, but I
have not heard any with my own VFO based on an AD9850.? I connect to the
VFO jack through a 0.1uf cap to pass a 5 MHz sine wave with VPP of 800
mv.? Does that sound right?? I'm not an RF engineer.? With f at 5 MHz I
assume I am tuned to 7 MHz and as the VFO f goes down the tuned signal
goes up.? Does that sound right too?? I need a reality check and a glass
of wine now.
Bob KF6ABC Mix?
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Re: 80 M and Shortwave receive to BITX40v3 (Non digital vfo )
This is great news. I have 2 BitX40 boards one I want to convert to 80 meters. Thanks for doing the ground work for me. Now to learn about arduino programing.....?
--
Mike VK3XL
|
I finally bit the bullet in my BitX40 by removing L4 to try my own VFO.?
The original radio worked and I heard many CW and SSB stations, but I
have not heard any with my own VFO based on an AD9850.? I connect to the
VFO jack through a 0.1uf cap to pass a 5 MHz sine wave with VPP of 800
mv.? Does that sound right?? I'm not an RF engineer.? With f at 5 MHz I
assume I am tuned to 7 MHz and as the VFO f goes down the tuned signal
goes up.? Does that sound right too?? I need a reality check and a glass
of wine now.
Bob KF6ABC Mix?
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toggle quoted message
Show quoted text
On Thu, Feb 9, 2017 at 6:31 PM, John Backo via Groups.Io <iam74@...> wrote: Ken:
They are T-37-6 toroids.? Toroids are classified by their diameter and their color.
Hence, T50-2 toroids would be 1/2 inch across and color red, usually used in a frequency range below 30m.
The usual colors for RF are? red (type 2). yellow (type 6) and white (type 7).
Beware of toroids that are yellow with a white side. They are common in switching power supplies. These are #26 material and are meant for low frequency switching.
Note that this nomenclature applies to powdered metal toroids. Ferrite toroids are different. Generally they are all black or grey. The same
size nomenclature applies but they a totally different mix. Usual ones in Rf are FT-37-43 and FT-37-61. The "FT" stands for "Ferrite Toroid".
FT's are usually used in broadband transformers and mixers.
check out the Amidon site for more information.
john
AD5YE
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You are shorting out one of the input resistors and increasing Vcc on the input darlington pair.
This is not a good idea, since it increases the current drain and heat generated. Pin 2 is for
"Bypass" and is meant to go to ground through a capacitor to filter out line noise. Your method
upsets the voltage balance of the internal transistors. Interesting idea though...
The best solution is probably a FET mute such as that commonly found to mute CW
receive during key down. It should be at the input and might have to be somewhat heftier than a 2N7000 (which is commonly used)
but I think a BS170 should handle it.
john
AD5YE
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Re: Possible PA low output problem. Problem SOLVED
The Vishay datasheet for BAT54 diodes lists the BAT54S SOT-23.
It has a marking "L44".
Note that the common output of this diode pair is where the old pot went (between the diodes).
If using separate diodes, some rearrangement might have to be made.
john
AD5YE
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Ken:
They are T-37-6 toroids. Toroids are classified by their diameter and their color.
Hence, T50-2 toroids would be 1/2 inch across and color red, usually used in a frequency range below 30m.
The usual colors for RF are red (type 2). yellow (type 6) and white (type 7).
Beware of toroids that are yellow with a white side. They are common in switching power supplies. These are #26 material and are meant for low frequency switching.
Note that this nomenclature applies to powdered metal toroids. Ferrite toroids are different. Generally they are all black or grey. The same
size nomenclature applies but they a totally different mix. Usual ones in Rf are FT-37-43 and FT-37-61. The "FT" stands for "Ferrite Toroid".
FT's are usually used in broadband transformers and mixers.
check out the Amidon site for more information.
john
AD5YE
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Re: Possible PA low output problem. Problem SOLVED
My Q13 seems fine with voltages in-line with Randy's voltage chart. I haven't checked everything yet. From much earlier posts about Q13, it was one of the first things I checked. I am still awaiting conformation from Tom on the part location and part number IL440. It's possible he's wrong. Really need others to confirm and comment. But if it's true I am gonna throw that wrong part into the sun!
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OK, I've done some experiments today:
1. connect a jumper wire between pin 7 and pin 4 (GND) - the audio was almost completely muted, but not 100%.
2. connect the jumper between pin 7 and pin 6 (+Vcc) - now the audio was muted completely!
So I'd guess this feature allows for a very elegant way to mute the audio during transmit - in fact much nicer than the way it's done in the current design (interrupt the input signal with relay K2).
Now I still need to find a way to somehow use the 12V at "TX" (from relay K1) for applying +Vcc to pin 7. Would it be safe to connect "TX" via 100 ohms to pin 7? In that case pin 7 would be at +Vcc during transmit, however at the same time pin 6 would then not be connected to the supply anymore (because it is connected to "RX"). I'm not sure if that would hurt the LM386.
Any ideas or other suggestions?
73, Allard
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Re: Possible PA low output problem. Problem SOLVED
Don't assume low power out is due to a bad diode pair. The two issues at Q13 mentioned below can both cause a "Possible PA low output problem" that would be indistinguishable from a bad diode pair in the modulator. ?Also could be a a damaged IRF510, perhaps from driving a high SWR load with 20v on the drain, or setting the bias control beyond 100ma quiescent. ?Or the microphone connector got shorted out. ?Or transformer wires shorted or broken. ?Or about half the remaining parts in the rig experiencing some sort of failure.
On Thu, Feb 9, 2017 at 12:19 pm, Jerry Gaffke wrote: Regarding post 19730, there's a couple issues a bit further down that we need to keep track of. 1) ?Q13 is dissipating an awful lot of heat for a Sot23, may need to adjust the emitter resistor there. 2) ?Having your Bitx40 hooked up to an antenna while some nearby antenna is transmitting at high power can blow Q13, may need Raj's dual diode plus lamp fix.
?
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Greg DL3GJ
Raj vu2zap
Allard PE1NWL