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Re: Building an antenna
re,
Sorry to post again on the antennas, but I¡¯m working on the subject, and the more I read about it, the more questions I have.
First of all, I thought the dipole had to have a total length of one wave, but I see a lot of constructions that are actually two-quarters of a wave, which is what we call double-half wave. This is interesting because the thread is shorter.
In addition I just read that a doublet on 7MHZ, also works on 21 MHZ with the third harmonic.
Here again I read that the impedance is more towards 73 ohms, but decreases with the height, so roughly 50ohm of coaxial is good.
So my question remains the same, I anticipated the possibility of 5 wires on each side of my dipole. What are the best lengths to provide (Knowing now that harmonics can play) to optimize the reception of maximum bands.?
The ubitx ranges from 1 to 30 mhz
thank you
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¿ªÔÆÌåÓýYes Fabian you can install the filter inline from the volume control. You will need a SPDT or if switching voltage on and off also a DPDT switch. In any case the audio amplifier input would be connected to the terminal that is switched (usually the center terminal) and the wiper of the volume pot to one of the outer terminals and the filter output to the other terminal. Here is a rough drawing of description.The LM317 and LM337 are different regulators one is in the positive flow and the other is in the negative side, use the 317 and you don¡¯t need a zener diode just use the resistor divider circuit on the output with a trimmer resistor to ground. You will be able to adjust it for your 10vdc. Skip Davis, NC9O? On Mar 26, 2022, at 09:35, sdr freak <sdrfreak55@...> wrote:
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Re: Building an antenna
Hello,
Some pictures of the progress of my antenna.
The connection box is made, the tubes pass wires and house insulators too.
It remains to calculate the length of the wires. surely with this tool.
After that, if we want to be a perfectionist, I could put on a ferrite balun or make a coaxial one.
You tell me if this is a plus for the reception.
I can get a ferrite from a small antenna I bought on A....o.
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cdt |
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Thank you for your help!
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I understood that it is now possible to operate the audio CW filter without a relay if I install a switch for the supply voltage, i.e. voltage for filter on/off, for example on the front of the UBitX. That would be the first switch.
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And now the real thing.
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I could also install the filter between the path of the line from the volume potentiometer to the audio IC.
And just a switch for shorting the normal volume to audio IC line.
That would be the second switch for filter on or off. Simply installed the switch for CW filter on/off on the front of the UBitX next to the volume potentiometer.
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If that corresponds to my considerations is it correct, please tell me, I'm a little inexperienced when it comes to all this. But I would always like to build a lot myself, I just find it difficult to understand some simple things.
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That would also be another question if I may, the supply voltage for the filter must be stabilized at 10V and LM337 and zener diodes and I thought about how to do that, on a stabilized supply voltage for the CW filter.. It's just that I use a battery with 13.5V-12.7V depending on the operation of my UBitX. So I don't have an exact input voltage to calculate something for a Z-diode, is that right? With a LM317/337 I thought it might work, but if I'm honest I can't find the right answer to this 13.5V-12.7V from the battery, which doesn't stay the same, to get a 10V stabilized voltage for the CW filter ..
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Can you please help me again how to do that with the 10V for the filter without 7810 IC?
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Thank you for your help! |
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Re: Power supply for Ubitx
Hello,
I found the source of the noise. (It's not directly 50 htz, but near to be heard.
My assembly being in "scratch", the small snore came from the sound potentiometer. it was enough to connect the mettalic part of it to the ground. Hence the importance of putting the assembly in a metal case.
In spite of doing my measurements, I notice this signal of about 20mv at the output of the demodulator (When no signal on the antenna, put it to ground)? which is after the filter SSB (go to Q70 --> M1? -->M2? --> input of the audio amplifier).
it won¡¯t fit in the audio amplifier , but I was wondering if it could be filtered, or if it was due to an unbalanced demodulator or something else (?)
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YOU WROTE:(De)ModulatorThe post filter signal is strong enough to not need an IF amplifier, so we directly take it to a balanced (de)modulator made out of two matched diodes. It is important to use matched diodes here as the same circuit is also used to modulate during transmission. Balance controls are pesky circuits, they are easily unbalanced and setting them properly is more difficult than finding two diodes with the same forward resistance and soldering in the pair. An easier option it to just order a small strip of the inexpensive BAT54S which come as pre-matched pair for a few pennies each. We use the remaining CLK#0 output of the Si5351 to drive the BFO. The carrier is permanently fixed to generate upper sideband signal. The sideband is inverted by flipping the second oscillator between 33 MHz and 56 MHz. ?When the second oscillator is at 34 MHz, the upper sideband propagates either way without inversion as 33 + 11 = 45 MHz. When the second oscillator is at 56 MHz, the 45 MHz is generated as 56-11 = 45 MHz. Note that in the second case, the 45 MHz signal will decrease in frequency as the 11 MHz signal is subtracted from 56 MHz, thus achieving sideband inversion. A few minutes of pencil and paper work will be required to figure out how this works.On my assembly, it is a set of diode made-up (BAT54SLT1G-dk_Diodes-Rectifiers-Arrays).? 2 diode in the same package
I¡¯ve still planned a location to put BAT54S diodes in case.
If the problem comes from there, do you have a method to test? a pair 2 diodes??
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¿ªÔÆÌåÓýFabian the relay is used to switch the filter in and out of the audio path. So if you are going to leave it in the audio circuit permanently the relay is not needed just jumper the proper relay contacts for power and audio. If you want to switch it in and out the 12vdc relay you have should work you will just need a switch to a 12v source on receive.Skip Davis, NC9O? On Mar 25, 2022, at 09:59, sdr freak <sdrfreak55@...> wrote:
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Hello to All,
i have an UBitX V3 and learned CW, but with an CW Filter it should be better for me to hear a Station, because i think everyone want like use an CW Filter for better hearing CW... My Components in my Case are a few LM324 i have here, and with the other Components to built an CW Filter like the one which VK4PLN created i already have... The only Problem is, i only have 12V Relay in here, but in the schematic is an 5V Relay recommended and i even thought, why is an Relay in the Circuit described, what job is that doing in the circuit, and can i built the main Circuit without a Relay and is there any way works like other CW Audio filter when i built it between the Audio Amp and the Volume Potentiometer Line?? I hope for help, thanks very much and please forgive me my english is not the best sorry Fabian de DD1FK |
Gerard
Skip Davis
sdr freak
Thomas White AD6TW