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Re: KB1GMX on the BITX
Yup. ?When operating the VFO down around 5mhz we get images of SW Broadcasters from the 4'th harmonic of the vfo, as first explained by PA4Q in post 21996. ?As you suggest, 7.2mhz gets received twice, once as LSB and once as USB. As a separate issue explained in post 21941, we get a birdie at 7.2mhz from the 5'th harmonic of the 4.8mhz vfo beating with the 2'd harmonic of the 12mhz BFO. The above two have both been complained about mightily over the last month or so. We can avoid both if we move the VFO up to the high side as per your recommendation. ?However, as noted in post 22005, the 8'th harmonic of the bfo can beat with the 5'th harmonic of the vfo, giving us a birdie at 7.2mhz. ? ?(Likely faint if there at all, and shielding the bfo/demodulator should kill it.) Conclusion: ?7200000 is an extremely inauspicious number for this radio.? Jerry, KE7ER On Mon, Feb 20, 2017 at 07:09 am, <ajp166@...> wrote:
The likely problem is interaction between the BFO and the LO causing a result at 7.2 when tuned to 7.2. ? |
Re: Unbalancing mixer
Using the digital chip for the bfo sounds like the answer but I know nothing about programming the Arduino and the digital chip so I'll have to wait until someone smarter decides to tackle it! ?:-)) Roy WA0YMH On Feb 20, 2017 9:39 AM, "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote:
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Re: Unbalancing mixer
Will work fine if you move the BFO a khz over into the crystal filter passband. ?Trivial if the BFO is driven from a second channel of the Si5351, and gives us a better option for USB/LSB switching as well. ?If you insist on analog, perhaps a varactor diode in the BFO as used on the analog vfo. See post?/g/BITX20/message/20933 Still no Bitx40 here though. On Mon, Feb 20, 2017 at 06:59 am, Roy Appleton wrote:
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Re: KB1GMX on the BITX
The likely problem is interaction between the BFO and the LO causing a result at 7.2 when tuned to 7.2. I used a SI70 and a crystal osc based on a spare crystal from builidng the filter for the BFO so I could isolate them and it was not an issue. ? Note I tried an actual 19mhz VFO and it worked fairly well but required really good construction to be stable. ?FYI there were/are commercial radio that use high VFOs namely Tentec Argonaut 505 and Atlas 180/210/215 and with good construction and temperature compensation I can say they work as I have both. ?It does take some effort and I've built a VFO at 14mhz that was very stable but mechanically involved. That brings up a possible issue. ?Long wires connecting things and shielding of stray signals. ?Care is required there as the NCO can and will radiate is the wires are somewhat random. -- |
Re: Need help with constant tone in audio output
ken barnes
try large capasitor ie ?50uf ?25 volt working ? ? across power supply............. On Monday, 20 February 2017, 13:51, Raj vu2zap <vu2zap@...> wrote:
FIrst I am suspecting the power supply. Second disconnect the volume plug and see, I would suspect the tone will be there if the PS is at fault. Third If the tone stops then suspect the preamp transistor or earlier. As you said you have disconnected the rest. Raj At 20/02/2017, you wrote: Good morning Jerry and the group, |
Re: Unbalancing mixer
So that means that unbalancing the mixer will never be a legitimate way to introduce a carrier for tuning purposes? Roy WA0YMH On Feb 19, 2017 10:37 PM, "Ashhar Farhan" <farhanbox@...> wrote:
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Re: Calibration
Jack Purdum
I also have that case, too, but I'm adding a Muppet board and there wasn't enough room for both in the Banggood case. It is, however, a very nice case. Jack, W8TEE From: Buck <RadioK4ia@...> To: [email protected] Sent: Monday, February 20, 2017 9:26 AM Subject: Re: [BITX20] Calibration A similar case is on Banggood but check the dimensions. Buck, k4ia Honor Roll 8BDXCC On 2/20/2017 9:13 AM, Jack Purdum via Groups.Io wrote: > I was looking for the order, but can't find it. The supplier was Allied > Electronics and the case was: > > > > They have a bazillion cases. If I can confirm the order, I'll post it to > the group. > > Jack, W8TEE > > > ------------------------------------------------------------------------ > *From:* Leo de Blaauw <L.deblaauw@...> > *To:* [email protected] > *Sent:* Monday, February 20, 2017 1:45 AM > *Subject:* Re: [BITX20] Calibration > > Hi Jack, > > Slightly off-topic, but may I ask what enclosure you are using ? > > regards and 73 > Leo de Blaauw - PD1LDB > > |
Re: Calibration
A similar case is on Banggood but check the dimensions.
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Buck, k4ia Honor Roll 8BDXCC On 2/20/2017 9:13 AM, Jack Purdum via Groups.Io wrote:
I was looking for the order, but can't find it. The supplier was Allied |
Re: Need help with constant tone in audio output
Good morning Larry, Success! Using a battery cleared up the tone. Now on to packing it up in its enclosure. Many thanks to all for helping including Jerry! 73, Chuck K3VPZ From: "Larry Acklin" <acklin@...> To: [email protected] Sent: Monday, February 20, 2017 8:30:31 AM Subject: Re: [BITX20] Need help with constant tone in audio output Try a battery supply.? My shack supply does not play nice with the BitX.? A small wall wart 2A, 12V is silent.? I get tone with the shack PS. Larry KB3CUF On Mon, Feb 20, 2017 at 8:01 AM, Chuck <chucke2@...> wrote:
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Re: Calibration
Jack Purdum
I was looking for the order, but can't find it. The supplier was Allied Electronics and the case was:? They have a bazillion cases. If I can confirm the order, I'll post it to the group. Jack, W8TEE From: Leo de Blaauw <L.deblaauw@...> To: [email protected] Sent: Monday, February 20, 2017 1:45 AM Subject: Re: [BITX20] Calibration Hi Jack, Slightly off-topic, but may I ask what enclosure you are using ? regards and 73 Leo de Blaauw - PD1LDB
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Re: Need help with constant tone in audio output
FIrst I am suspecting the power supply.
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Second disconnect the volume plug and see, I would suspect the tone will be there if the PS is at fault. Third If the tone stops then suspect the preamp transistor or earlier. As you said you have disconnected the rest. Raj At 20/02/2017, you wrote: Good morning Jerry and the group, |
Re: Need help with constant tone in audio output
Try a battery supply.? My shack supply does not play nice with the BitX.? A small wall wart 2A, 12V is silent.? I get tone with the shack PS. Larry KB3CUF On Mon, Feb 20, 2017 at 8:01 AM, Chuck <chucke2@...> wrote:
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Re: Need help with constant tone in audio output
Good morning Jerry and the group, Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise. 73, Chuck K3VPZ From: "Jerry Gaffke via Groups.Io" <jgaffke@...> To: [email protected] Sent: Sunday, February 19, 2017 4:59:53 PM Subject: Re: [BITX20] Need help with constant tone in audio output Did you enable the analog vfo by adding L4? If the tone is still there with no vfo, that's a hint On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote: Have disconnected the Raduino, tone still there. ? |
Re: BITX40
The current drawn will depend upon the peak to average ration of the voice characteristics which is different for every individual. That is why a speech processor would be a great help to maintain a quasi-constant level. Regards Lawrence On Mon, Feb 20, 2017 at 2:50 AM, John Smith via Groups.Io <johnlinux77@...> wrote:
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Re: BITX40
It is standard practice that to eliminate any source of noise the decoupling has to be as near the source as possible using capacitors suitable for the frequency/ies involved. This also aids stability. Shielding of the readout and its wiring will also help. Using shielded cables including in the audio stages is also standard practice. Regards Lawrence On Sun, Feb 19, 2017 at 3:30 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Re: KB1GMX on the BITX
Hi, Has anyone had any success in getting the bitx40 running with VFO at 19Mhz? I tried last night and observations were: Drive out of the raduino needed to increase to 4ma before any noise came out of the receiver. Frequency measured at the output of Q7 was not 19Mhz??? Tested BFO at both 11.9985 and 12.0015 made no difference to resolving a signal. I have a trimmer cap at the BFO. C103. I'm wondering if the normal pins are the right place to inject the VFO. And there was still a birdie at 7.200Mhz- with no antenna just dummy load.? Also, varying the BFO varies the frequency of the birdie at 7.2Mhz for both VFO frequencies. Another observation, the birdie was louder with increased drive out of the raduino. Regards Simon VK3ELH ? |
Re: BFO Location
You will find a single 12Mhz xtal with some components next to the 860 - thats the bfo.
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73 Raj At 20/02/2017, you wrote:
Hi, |