Re: Power amplifier and lowpass filter
design it ... spread out in the wild as open source ... and
within a few weeks the chinese cloners will make a (much cheaper)
clone of it
no idea if you will get those 100.000 units :-)
dg9bfc sigi
Am 31.03.2022 um 22:50 schrieb Dan
Eggers N7DE:
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Show quoted text
What I want to do is to have
100,000 or more of these amplifiers made at low cost to get
people to upgrade from Technician to General or higher and get
on the HF bands, so that can not be done with salvaged parts,
because there are not 100,000 or more surplus basket cases out
there.
I am going to do what I can to
see if a 160 - 6 m 70 db lowpass filter can be made from
available parts at reasonable cost, but I did not want to do
that if one was already available.
TNX? ? 73, Dan, N7DE
i have a dead 757 gx (processor is made from unobtanium) ...
i was thinking of adding an sdr board (hermes light) to it ...
but the? bitx is also a nice idea :-)
dg9bfc sigi)
Am 31.03.2022 um 20:36 schrieb
Tim King, Jr AG4RZ:
The amp I currently use with my QRP stuff (5
watts in, 100 out) is actually a salvaged?setup.
I came across an old icom IC-720 that had a dead
microprocessor, but the PA was good..as was the LPF.?
Luckily, the final section accepted 5 watts from the
predriver..so, I gutted everything, and after sorting out
how the bandpass switching worked (diode driven rotary
relay) I programmed up an arduino to handle switching, and
added a 16x2 display to show me band selection, as well as
power out and SWR.? (Both of which are obtained from the
detector circuit I also salvaged)
I have less than $50 US in the whole thing, and I have
160-10.
Point is, an old HF rig that "wont?power up," or "turns
on but won't tune" might just be the perfect source for a
100 watt capable amplifier.
In addition, I got a ton?of nice parts for the junkbox,
including the predriver that goes from milliwatts to 5
watts, and is broad-banded as well.? Also, a little time
spent searching the web will often turn up the service
manual, which is really helpful.
Tim A. King Jr.
Amateur Radio Station AG4RZ
On Thu, Mar 31, 2022 at
2:01 PM Evan Hand < elhandjr@...> wrote:
I have bought both the kit and assembled version of the
"Chinese" LPF.? They are just 5 pole filters, so only
about 30DB down at the second harmonic as measured on my
NanoVNA.? The assembled version had a wrong capacitor in
one of the filters, and 4 of the 8 toroids wound
incorrectly.? I would not recommend the assembled version
unless you like to rework the board.? I would only use it
after a push-pull amp with a clean input signal.? I, too,
am still looking for a 7 pole 100watt filter assembly.? I
found one out of stock, though at $120, pretty pricey.
FWIW
73
Evan
AC9TU
|
Re: Power amplifier and lowpass filter
Currently out of stock.? Says the seller will be back today.? I will check tomorrow.
73
Evan
AC9TU
|
Re: Power amplifier and lowpass filter
What I want to do is to have 100,000 or more of these amplifiers made at low cost to get people to upgrade from Technician to General or higher and get on the HF bands, so that can not be done with salvaged parts, because there
are not 100,000 or more surplus basket cases out there.
I am going to do what I can to see if a 160 - 6 m 70 db lowpass filter can be made from available parts at reasonable cost, but I did not want to do that if one was already available.
TNX? ? 73, Dan, N7DE
toggle quoted message
Show quoted text
i have a dead 757 gx (processor is made from unobtanium) ... i was thinking of adding an sdr board (hermes light) to it ... but the? bitx is also a nice idea :-)
dg9bfc sigi)
Am 31.03.2022 um 20:36 schrieb Tim King, Jr AG4RZ:
The amp I currently use with my QRP stuff (5 watts in, 100 out) is actually a salvaged?setup.
I came across an old icom IC-720 that had a dead microprocessor, but the PA was good..as was the LPF.? Luckily, the final section accepted 5 watts from the predriver..so, I gutted everything, and after sorting out how the bandpass switching worked (diode
driven rotary relay) I programmed up an arduino to handle switching, and added a 16x2 display to show me band selection, as well as power out and SWR.? (Both of which are obtained from the detector circuit I also salvaged)
I have less than $50 US in the whole thing, and I have 160-10.
Point is, an old HF rig that "wont?power up," or "turns on but won't tune" might just be the perfect source for a 100 watt capable amplifier.
In addition, I got a ton?of nice parts for the junkbox, including the predriver that goes from milliwatts to 5 watts, and is broad-banded as well.? Also, a little time spent searching the web will often turn up the service manual, which is really helpful.
Tim A. King Jr.
Amateur Radio Station AG4RZ
On Thu, Mar 31, 2022 at 2:01 PM Evan Hand < elhandjr@...> wrote:
I have bought both the kit and assembled version of the "Chinese" LPF.? They are just 5 pole filters, so only about 30DB down at the second harmonic as measured on my NanoVNA.? The assembled version had a wrong capacitor in one of the filters, and 4 of the
8 toroids wound incorrectly.? I would not recommend the assembled version unless you like to rework the board.? I would only use it after a push-pull amp with a clean input signal.? I, too, am still looking for a 7 pole 100watt filter assembly.? I found one
out of stock, though at $120, pretty pricey.
FWIW
73
Evan
AC9TU
|
Re: Power amplifier and lowpass filter
i have a dead 757 gx (processor is made from unobtanium) ... i
was thinking of adding an sdr board (hermes light) to it ... but
the? bitx is also a nice idea :-)
dg9bfc sigi)
Am 31.03.2022 um 20:36 schrieb Tim
King, Jr AG4RZ:
toggle quoted message
Show quoted text
The amp I currently use with my QRP stuff (5 watts
in, 100 out) is actually a salvaged?setup.
I came across an old icom IC-720 that had a dead
microprocessor, but the PA was good..as was the LPF.? Luckily,
the final section accepted 5 watts from the predriver..so, I
gutted everything, and after sorting out how the bandpass
switching worked (diode driven rotary relay) I programmed up
an arduino to handle switching, and added a 16x2 display to
show me band selection, as well as power out and SWR.? (Both
of which are obtained from the detector circuit I also
salvaged)
I have less than $50 US in the whole thing, and I have
160-10.
Point is, an old HF rig that "wont?power up," or "turns on
but won't tune" might just be the perfect source for a 100
watt capable amplifier.
In addition, I got a ton?of nice parts for the junkbox,
including the predriver that goes from milliwatts to 5 watts,
and is broad-banded as well.? Also, a little time spent
searching the web will often turn up the service manual, which
is really helpful.
Tim A. King Jr.
Amateur Radio Station AG4RZ
On Thu, Mar 31, 2022 at 2:01
PM Evan Hand < elhandjr@...>
wrote:
I
have bought both the kit and assembled version of the
"Chinese" LPF.? They are just 5 pole filters, so only about
30DB down at the second harmonic as measured on my NanoVNA.?
The assembled version had a wrong capacitor in one of the
filters, and 4 of the 8 toroids wound incorrectly.? I would
not recommend the assembled version unless you like to rework
the board.? I would only use it after a push-pull amp with a
clean input signal.? I, too, am still looking for a 7 pole
100watt filter assembly.? I found one out of stock, though at
$120, pretty pricey.
FWIW
73
Evan
AC9TU
|
UBITX V4 to V5 board switch
I have a V4 with a 2.8 Nexitron display running KD8CEC firmware. I built it in 2017. It has been great until my power supply output transistors shorted putting 27v to the radio. The transmit side is still fine, but the receive side is dead. The audio seems ok as my CW side tone still works, but I get nothing from the receive circuit to the audio.?
It is not obvious to me what has been damaged.
I do have a new V5 board. I purchased a unbuilt kit from a guy a year or so ago.
My first question is what do you suspect I blew up. I know it is very hard to guess.
My second Question is what firmware do I need for ?V5, 2.8 nexitron, extra arduino for SWR, using CAT control?
Also is there any difference in the Raduino between V4 and V5?
Thanks
John Faivre?WA9SGD
|
Hi Gary, I keep fighting with the frequencies...?fortunately, it seems that everything has passed.
Indeed, what I am trying to do is place the spectrum of the vocal band in the most favorable position in both filters.
In the 45 MHz filter, the center of the voice band should coincide with the center of the filter because the bandwidth of the filter is much larger.
In the case of the 11.059MHz filter, it is not so clear to me, because the filter bandwidth (2570Hz) is less than the voice band (3400-300=3100Hz) and we have to choose which part of the voice spectrum we want to reduce. Regarding the values that you send me, and referring only to USB-RX,?I see a small mismatch: if the formula marked in red is applied, we obtain 54,998,625 Hz for the 1st intermediate frequency. Placing this frequency on the filter curve, we see that the spectrum of the vocal band would be shifted to the left (see drawing, green arrow),?leaving 2570 Hz on the left and 300 Hz on the right.   For this case (USB-RX), the formula for OSC2 should be:? OSC2 = freq + RoofFiltCenterFreq + AudioLowFreq + (AudioUpperFreq-AudioLowFreq) / 2?Thus, we will have: 10000000 + 44998325 + 300 + (2870-300)/2 = 54999910Hz.?This shifts the spectrum 1285 Hz to the right and leaves the vocal band (300-2870) centered in the filter.
I have implemented this in code as follows:
I have defined 2 operating modes, Normal Mode and Optimal Mode. I have added in the configuration the values
- fc1= central frequency of filter 1
- df1=bandwidth of filter 1
- fc2=center frequency of filter 2
- df2=bandwidth of filter 2
These values can be changed in the settings menu. ?  I have created this function to fix the clock frequencies in Optimal mode.  Also, for checking, the main screen can be put into a mode that allows you to view the frequencies.  I have prepared a diagram with all this mess.?Note that I'm considering a slightly higher vocal band, 300 to 3400 Hz. I'll incorporate this as a configuration setting anyway.   I need to test and measure all of this, although I'm not really sure that it will make a very significant advance in practice. I will send you the Excel file that I am using. Saludos,
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Re: Power amplifier and lowpass filter
The amp I currently use with my QRP stuff (5 watts in, 100 out) is actually a salvaged?setup.
I came across an old icom IC-720 that had a dead microprocessor, but the PA was good..as was the LPF.? Luckily, the final section accepted 5 watts from the predriver..so, I gutted everything, and after sorting out how the bandpass switching worked (diode driven rotary relay) I programmed up an arduino to handle switching, and added a 16x2 display to show me band selection, as well as power out and SWR.? (Both of which are obtained from the detector circuit I also salvaged)
I have less than $50 US in the whole thing, and I have 160-10.
Point is, an old HF rig that "wont?power up," or "turns on but won't tune" might just be the perfect source for a 100 watt capable amplifier.
In addition, I got a ton?of nice parts for the junkbox, including the predriver that goes from milliwatts to 5 watts, and is broad-banded as well.? Also, a little time spent searching the web will often turn up the service manual, which is really helpful.
Tim A. King Jr.
Amateur Radio Station AG4RZ
On Thu, Mar 31, 2022 at 2:01 PM Evan Hand < elhandjr@...> wrote: I have bought both the kit and assembled version of the "Chinese" LPF.? They are just 5 pole filters, so only about 30DB down at the second harmonic as measured on my NanoVNA.? The assembled version had a wrong capacitor in one of the filters, and 4 of the 8 toroids wound incorrectly.? I would not recommend the assembled version unless you like to rework the board.? I would only use it after a push-pull amp with a clean input signal.? I, too, am still looking for a 7 pole 100watt filter assembly.? I found one out of stock, though at $120, pretty pricey.
FWIW
73
Evan
AC9TU
|
Re: Power amplifier and lowpass filter
I have bought both the kit and assembled version of the "Chinese" LPF.? They are just 5 pole filters, so only about 30DB down at the second harmonic as measured on my NanoVNA.? The assembled version had a wrong capacitor in one of the filters, and 4 of the 8 toroids wound incorrectly.? I would not recommend the assembled version unless you like to rework the board.? I would only use it after a push-pull amp with a clean input signal.? I, too, am still looking for a 7 pole 100watt filter assembly.? I found one out of stock, though at $120, pretty pricey.
FWIW
73
Evan
AC9TU
|
Re: Power amplifier and lowpass filter
I would then say that I have the power amplifier problem solved.? What gets expensive is capacitors that can handle the voltages involved.
Communications-Concepts sells? single band lowpass filters for about $15 that can handle 500-watts.? They use T106 cores.? I am using one for 40 m and one for 20 m in my amplifier.? $45 is not that much after inflation, so I thought
that I would order one of the Chinese 4 band lowpass filters, and I will let you know what I think of it after I get it put together.? ? ? ? ?73, Dan
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The sbitx can put out 40 watts, but it is not recommended, as it can produce IMD. There are no plans for anything more than this power. The low pass filters, heatsinks and the power supplies become expensive.
That said, it is easy to make a one or two band linear amplifier with MRF101 (100 watts per transistor) or the MRF300 (300 watts per transistor). You can make air-core coils and use RG58 stubs as high voltage capacitors. This will be a bulky
but cheap and high performance linear amplifier.
- f
On Thu, Mar 31, 2022, 8:40 PM Dan Eggers N7DE < N7DE@...> wrote:
- Will future microBITX transceivers have 80-Watts of output?? If so no amplifier is needed.
- I made a 50-Watrt 160 - 10 m amplifier for $95.? If you pay $65.32 more for transistors and $130 for a larger power supply you can have 100-w
- Lowpass filter boards - are there any 5, 6, or 7 band boards available?
- ? ?The Chinese have a 4 band 50 db board for $45? I think paying $100 is OK.
- ? ?5 bands of 70 db filters for 80 - 10 m is the minimum I would really like to have.
- ? ?6 bands of 70 db filters for 160 - 10 m would be better.
- ? ?7 bands of 70 db filters for 160 - 6 m would be best like ICOM, Kenwood, Yeasu
The slope of the 50 db skirt is not steep enough to be 43 db down at the second harmonic.? However, if you assume that the input is a square wave (lots of harmonics), then the second harmonic is already down 17 db plus the
50 db skirt would be enough to be 43 db down, so 50 db filter boards with 5, 6, or 7 filters would still be of interest.
Thank you?for whatever information you can provide me with.? ?73, Dan Eggers, N7DE?
N7DE@...
|
Hello,
The assembly of my antenna in my attic is progressing, it is not yet completely finished.
I wanted to know if there was anything we could do for security.
You have to know that the transceiver will not be permanently connected, so the antenna connector plug will end up on the floor in my room.
On this article, we fear nothing when it is in the attic, the most dangerous would be an external vertical antenna.
We sell lightning arresters, some make one with a car candle. or nothing to do, protected by the attic (?)  cdt ?
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Hola Ram¨®n, I hope that you and your family are doing better. Believe I understood what you are attempting to do.? But to my understanding, the equations as proposed in your filter characterization document won't achieve that goal. With the implementation of the equations in the notes below, a RX test case has been validated while listening to BCAM.? Able to shift the audio pass band up and down and can hear the difference. Have not tested/verified TX, but it works out fine in the spreadsheet. (Caveat emptor :-)? If there is an error in my notes, please bring it to my attention. I planned to compared to the Pass Band Tuning scheme that Jerry had sent out, but that got side tracked. So incomplete work, but it still may be of some assistance for your project. Rgds, Gary  
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Re: Power amplifier and lowpass filter
The sbitx can put out 40 watts, but it is not recommended, as it can produce IMD. There are no plans for anything more than this power. The low pass filters, heatsinks and the power supplies become expensive. That said, it is easy to make a one or two band linear amplifier with MRF101 (100 watts per transistor) or the MRF300 (300 watts per transistor). You can make air-core coils and use RG58 stubs as high voltage capacitors. This will be a bulky but cheap and high performance linear amplifier. - f
On Thu, Mar 31, 2022, 8:40 PM Dan Eggers N7DE < N7DE@...> wrote:
- Will future microBITX transceivers have 80-Watts of output?? If so no amplifier is needed.
- I made a 50-Watrt 160 - 10 m amplifier for $95.? If you pay $65.32 more for transistors and $130 for a larger power supply you can have 100-w
- Lowpass filter boards - are there any 5, 6, or 7 band boards available?
- ? ?The Chinese have a 4 band 50 db board for $45? I think paying $100 is OK.
- ? ?5 bands of 70 db filters for 80 - 10 m is the minimum I would really like to have.
- ? ?6 bands of 70 db filters for 160 - 10 m would be better.
- ? ?7 bands of 70 db filters for 160 - 6 m would be best like ICOM, Kenwood, Yeasu
The slope of the 50 db skirt is not steep enough to be 43 db down at the second harmonic.? However, if you assume that the input is a square wave (lots of harmonics), then the second harmonic is already down 17 db plus the
50 db skirt would be enough to be 43 db down, so 50 db filter boards with 5, 6, or 7 filters would still be of interest.
Thank you?for whatever information you can provide me with.? ?73, Dan Eggers, N7DE? N7DE@...
|
Power amplifier and lowpass filter
- Will future microBITX transceivers have 80-Watts of output?? If so no amplifier is needed.
- I made a 50-Watrt 160 - 10 m amplifier for $95.? If you pay $65.32 more for transistors and $130 for a larger power supply you can have 100-w
- Lowpass filter boards - are there any 5, 6, or 7 band boards available?
- ? ?The Chinese have a 4 band 50 db board for $45? I think paying $100 is OK.
- ? ?5 bands of 70 db filters for 80 - 10 m is the minimum I would really like to have.
- ? ?6 bands of 70 db filters for 160 - 10 m would be better.
- ? ?7 bands of 70 db filters for 160 - 6 m would be best like ICOM, Kenwood, Yeasu
The slope of the 50 db skirt is not steep enough to be 43 db down at the second harmonic.? However, if you assume that the input is a square wave (lots of harmonics), then the second harmonic is already down 17 db plus the
50 db skirt would be enough to be 43 db down, so 50 db filter boards with 5, 6, or 7 filters would still be of interest.
Thank you?for whatever information you can provide me with.? ?73, Dan Eggers, N7DE? N7DE@...
|
Re: Owning A ShortWave Radio Is Once Again A Subversive Activity
On Wed, Mar 30, 2022 at 09:02 PM, Jerry Gaffke wrote:
Spark transmitters were still found on board ships at least into the 1950's as backup transmitters and stowed away on lifeboats.
Just yet another reason why the castaways never seemed to be able to get off Gilligan's island. Their shipwrecked boat must have had a diesel engine, forcing the professor into a deluded attempt to make a transmitter out of coconut shells rather than a salvaged spark coil.? Tom, wb6b
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Re: Owning A ShortWave Radio Is Once Again A Subversive Activity
When I was 14 an older ham who worked with my father gave me stuff from his junk box that he no longer planned to use.? Included some 810 transmitting triodes and a plate transformer suitable to power them.? I managed not to kill myself with that stuff.? Also a bunch of Ford spark coils, which had been used by amateurs till 1924. Spark transmitters were still found on board ships at least into the 1950's as backup transmitters and stowed away on lifeboats.??
Jerry, KE7ER
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Re: This is a test message
Got your message ?Dan. W3BU
Not sure if I missed something. ?If so let me know. ? Dan
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On Mar 30, 2022, at 9:38 PM, Jim via groups.io <jlckansas@...> wrote:
?It is not a test, it is a celebration of your knowledge on a subject.
TY
Jim
KE0VVU
|
Re: This is a test message
It is not a test, it is a celebration of your knowledge on a subject.
TY
Jim
KE0VVU
|
|
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Hello,
I have a 6.1 uBitx for sale complete and assembled. It includes Jim Sheldon's Teensy 4.1 Raduino () and? the microphone. It includes a TalentCell 12V 9Ah lithium Ion battery. ()
The mods etc. are a little over? my head and soldering skills for surface mount.
I was thinking $170 (or offer) plus shipping.
Gary
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Re: Owning A ShortWave Radio Is Once Again A Subversive Activity
Too funny
Ken, N2VIP
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Show quoted text
On Mar 30, 2022, at 06:16, Bob Lunsford via groups.io <nocrud222@...> wrote:
Model-T spark (ignition) coils put out 60-80,000Volts. In 1955, I built a spark coil transmitter with one abd when I left Sanford, FL for Brazil, I gave it to a friend that wanted to become a ham and he used it for code practice with the spark coil's buzzer contacts. he told me the engineer from the local radio station about 1/4 mile away came and took it away for causing interference...
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Gerard
