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Re: BITX40
Instead, you can use 4K7 or some such pull up, Please check. regards Sarma ? On Wed, Nov 29, 2017 at 9:22 PM, Gert Krause <krause-gk@...> wrote: Hi |
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Re: BITX40
Hi
the problem is solved in an brutal amateur way : the solution with a resistor did`n work so I connected A2 dirctly to +5V. Now the ability of calibrating the offset is lost but that?s a thing I can live with, it?s better than buying somthing new. I think the start of the problem was the other selfmade 6W- rig on my table : I tested both on a dummyload for outputpower separatly, all the cables of the BITX in originaly length wound to a smal ring, probably a fine coil with high induction ! I forgot all about the physics I once learned ! Thank?s for your help anyway, hope to meet you on the band one day 73 Gert DG3OQ |
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Re: Help me understand the USB (upper side band) mod
Gordon Gibby
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From: [email protected] <[email protected]> on behalf of Ashhar Farhan <farhanbox@...>
Sent: Wednesday, November 29, 2017 3:38 AM To: [email protected] Subject: Re: [BITX20] Help me understand the USB (upper side band) mod ?
Lets take a concrete example.
An lsb signal generated at 12 mhz carrier, now considee that it is modulated with a 500 hz carrier, it produces a signal at 11,999,500 hz. If the modulating carrier is at 1khz, the signal will shift further down to 11,999,000 hz.
Now, lets mix this with a? 5 mhz oscillator. The lsb signal will be subtracted from the 12 mhz signal. The 11,999,500 - 5,000,000 = 6999,500? mhz. The 1khz signal will be even lower at 11,999,000 - 5,000,000 = 6,999,000. Thus as the modulating
tone moves up, the rf moves down, it is still LSB.
Now, consider the local oscillator at 19 mhz. Here, the signal is subtracted from the 12hz signal (the previous example had oscillator subtracted from the 12 mhz if). So, 19,000,000 - 11,999,500 = 7000,500 is the frequency of the signal at 500
hz is 700.5 khz. When the audio shifts to 1000 hz, the IF is at 11,999,000 and the rf is at 19,000,000 - 11,999,000 = 7001,000 hz. That is 7001 khz. Thus, the rf frequency moves up as the audio tone goes up. We are in USB!!
On 29 Nov 2017 1:33 pm, "Dale Brooks KG7SSB" <kg7ssb@...> wrote:
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Re: Help me understand the USB (upper side band) mod
Lets take a concrete example. An lsb signal generated at 12 mhz carrier, now considee that it is modulated with a 500 hz carrier, it produces a signal at 11,999,500 hz. If the modulating carrier is at 1khz, the signal will shift further down to 11,999,000 hz. Now, lets mix this with a? 5 mhz oscillator. The lsb signal will be subtracted from the 12 mhz signal. The 11,999,500 - 5,000,000 = 6999,500? mhz. The 1khz signal will be even lower at 11,999,000 - 5,000,000 = 6,999,000. Thus as the modulating tone moves up, the rf moves down, it is still LSB. Now, consider the local oscillator at 19 mhz. Here, the signal is subtracted from the 12hz signal (the previous example had oscillator subtracted from the 12 mhz if). So, 19,000,000 - 11,999,500 = 7000,500 is the frequency of the signal at 500 hz is 700.5 khz. When the audio shifts to 1000 hz, the IF is at 11,999,000 and the rf is at 19,000,000 - 11,999,000 = 7001,000 hz. That is 7001 khz. Thus, the rf frequency moves up as the audio tone goes up. We are in USB!! On 29 Nov 2017 1:33 pm, "Dale Brooks KG7SSB" <kg7ssb@...> wrote:
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Re: Help me understand the USB (upper side band) mod
Dale Brooks KG7SSB
Can someone answer this question for me. The latest sketch 1-27-2 has switching for UPS and LSB by pressing the function button (VFO sel. a/b) if I remember right. How is this accomplished by the Raduino output acting only as a single output VFO? I could see it if it also controlled the BFO frequency but this is not the case for the BITX40.? Dale KG7SSB On Tue, Nov 28, 2017 at 10:00 PM, John Backo via Groups.Io <iam74@...> wrote: But remember, Clark, that the "carrier" is the BFO frequency. We can |
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Re: Help me understand the USB (upper side band) mod
But remember, Clark, that the "carrier" is the BFO frequency. We can
adjust that to be about anything we want within reason. Changing the center frequency changes the position of the sidebands. In a SSB rig, we actually change that to get the best response for the sidebands from the filter. The filter itself doesn't change. How it is constructed will determine the bandwidth, but not the actual frequencies that go through it. The position of the BFO does that. It also means that if a given filter allows the USB through, shifting the BFO will allow the LSB through. BUT the position of the frequencies will be reversed (inverted). So the LSB will come out "upside down". But that doesn't matter as the transmitted frequency is determined by the mixer, not the BFO. And the other receiver's mixer determines what is extracted -- it can extract that "inverted" signal and set it "right side up" in its own crystal filter. So the other side hears a regular audio signal. That also means that any carrier that gets out of the mixer can go through the filter if the BFO is positioned right. Ordinarily in SSB, any suppressed carrier that gets out of the mixer is cut off by the filter. The sides of the filter are designed to do this -- but one could, if one wanted, unbalance the mixer, center the BFO on the mixer signal, and get a form of CW through the filter. The result is indistinguishable from a true A1 CW signal. So it's all about the BFO and the shape of the filter... john AD5YE |
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Re: Installing Firmware Upgrade
Vince Vielhaber
If you didn't delete the old version before you installed the new one, the libraries should still be there. Actually the added libraries (the ones you installed) should be in the project directory tree.
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Vince. On 11/28/2017 11:16 PM, Curt M. wrote:
Hi guys, I¡¯m running the latest version of the Bitx40 firmware, I --
Michigan VHF Corp. |
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Installing Firmware Upgrade
Hi guys, I¡¯m running the latest version of the Bitx40 firmware, I believe it¡¯s 1.27.2.?
Tonight I had a catastrophe with the laptop that I typically use to do the upgrades. I installed the latest Arduino 1.8.5 on a different machine. While I still remember how to install an upgrade I can¡¯t remember what libraries that I need to install to get it to the point that I need to be for when the next firmware happens to come out.? Can someone tell me what libraries need to be installed or point me in the direction of the original instructions on what to do to get back to where I need to be.? Thanks, Curt |
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Re: Help me understand the USB (upper side band) mod
¿ªÔÆÌåÓýThe Bitx uses a Double Balanced Modulator (DBM). ?If it's truly balanced it doesn't generate a carrier, just the two sidebands. If it didn't, it's unlikely the crystal filter could remove the carrier. ?The carrier is close to either side band and it's as strong a signal or stronger than the sideband.? Sent from an iPhone, don't ask whose. On Nov 28, 2017, at 2:16 PM, nphektor@... wrote:
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Re: Just want a USB switch
Congratulations to you and your daughter getting your tickets. I wish her luck on the general class exam. I would build the bitx stock and run it for a few weeks, then upgrade to one of Allard's sketches and do the hardware mods. I am using my bitx for the same purpose as you, ft8 and phone. I find the dual VFO option very useful to switch between these modes. The modifications associated with Allard's sketches are not hard to do. I think I am at 1.21. It is a fine ft8 radio. I have it tuned for lower output, with no additional heat sink, and drive a small amplifier. I have made contacts with a couple watts. At the present, I have worked all 50 states digital and would guess 30+ countries mostly Europe and the South Pacific due to the antenna favoring those directions.?
Here is a link to my build. I have included the duinovox for ft8 as part of the build.??/g/BITX20/topic/new_bitx40_build/5769825?p=Created,,,20,1,0,0&jump=1 If you facebook, the group "QRP Bitx40v3? 40 m radio kit" by Ryan W7RLF is a good one to join. Good Luck, and have fun with new radio build.? |
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Re: Bitx40 tuning question
Vince Vielhaber
Somebody already has. Michael (WA6ISP) did it, I think. There's another one out there somewhere too. I'm sure Michael will chime in shortly.
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Vince. On 11/28/2017 06:50 PM, CX8ABF Carlos Molina wrote:
HI Allard and all on the group --
Michigan VHF Corp. |
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Bitx40 tuning question
HI Allard and all on the group
I do not know about aruino programming, my query is simple, maybe the answer is difficult. It is possible to modify the raduino sketch, to use a rotary encoder instead of the potentiometer? Thanks in advance. Carlos CX8ABF. -----Mensaje original----- From: Allard PE1NWL 73 Allard PE1NWL |
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Re: Help me understand the USB (upper side band) mod
There is an excellent posting by Jerry Gaffke, KE7ER, that explains it all:
/g/BITX20/message/24724 73 Allard PE1NWL |
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Re: Help me understand the USB (upper side band) mod
Gordon Gibby
¿ªÔÆÌåÓýMaybe just a little more clarification on that.
When you mix and take the sum, you don't change the side band.
When you mix and take the difference, you actually invert the side band.
The relationship between the BFO oscillator & the crystal filter passband forces which side band will be created (transmitter) ?or detected (receiver). ? Unless you can move the BFO freq you can't pick up both sidebands, no matter
how you turn the VFO dial. ?
Sent from my iPhone
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Re: Help me understand the USB (upper side band) mod
The crystal filter is just a gateway it doesn't carevwhat type of rf gets through...? We're simply choosing which half of an am signal to pass...? By moving the signal up or down the spectrum by changing the signal frequency. We can theoretically pass the carrier and a small portion of both sidebands by selecting the proper frequency on the dial
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Allard PE1NWL
CX8ABF Carlos Molina
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