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BFO Calibration and SSB Carrier Suppression
#ubitx
#v6
If you have a wide filter AM position on your regular rig you could even feed the static from an open frequency into the mic and see what happens.
If you have a wide filter AM position on your regular rig you could even feed the static from an open frequency into the mic and see what happens.
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Tim Gorman
· #75788
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Changing direction - ignition noise intractable
#bitx40
If the ts-520 doesn't pick up the ignition noise and the bitx-40 does then it is shielding in the radio's that are the difference. A hole cut in the front panel for an lcd is a *big* hole for ignition
If the ts-520 doesn't pick up the ignition noise and the bitx-40 does then it is shielding in the radio's that are the difference. A hole cut in the front panel for an lcd is a *big* hole for ignition
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Tim Gorman
· #67402
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Pseudo-Sine?
Evan, IIRC this is how the old Collins KWM-2 used to do CW. Injection of an audio tone. Again, IIRC that's how you did the spot function on cw, turn on the audio osc and zero beat it with the received
Evan, IIRC this is how the old Collins KWM-2 used to do CW. Injection of an audio tone. Again, IIRC that's how you did the spot function on cw, turn on the audio osc and zero beat it with the received
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Tim Gorman
· #66034
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Spectrum test on the second V5 build SURPRISING results
#ubitx
If on CW we are truly just using a square wave for a signal then Jim is correct, the LPF for 80m is just not sufficient. The 3rd harmonic on a square wave is what, about 10db below the fundamental? So
If on CW we are truly just using a square wave for a signal then Jim is correct, the LPF for 80m is just not sufficient. The 3rd harmonic on a square wave is what, about 10db below the fundamental? So
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Tim Gorman
· #65905
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Spectrum test on the second V5 build SURPRISING results
#ubitx
Odd order harmonics are typical of a square wave. f, 3f, 5f, ..... This tells me somewhere in the amplifier chain there is a stage that is being overdriven significantly and the output of the amp is f
Odd order harmonics are typical of a square wave. f, 3f, 5f, ..... This tells me somewhere in the amplifier chain there is a stage that is being overdriven significantly and the output of the amp is f
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Tim Gorman
· #65902
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2nd run of the spectrum test on the V5
#ubitx
Jim, These graphs don't show much more than the earlier ones. 2nd harmonic on 80m and 3rd harmonic on 40m/20m need to be investigated. A low pass filter for each band could fix these but it would be b
Jim, These graphs don't show much more than the earlier ones. 2nd harmonic on 80m and 3rd harmonic on 40m/20m need to be investigated. A low pass filter for each band could fix these but it would be b
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Tim Gorman
· #65728
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Initial spectrum test on the V5 with my new spectrum analyzer
#ubitx
Not a problem, Jim. When I get mine I'll do the test. For spurs you shouldn't need a two-tone generator, just a simple audio oscillator. You might want to make sure you aren't seeing some kind of weir
Not a problem, Jim. When I get mine I'll do the test. For spurs you shouldn't need a two-tone generator, just a simple audio oscillator. You might want to make sure you aren't seeing some kind of weir
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Tim Gorman
· #65723
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Initial spectrum test on the V5 with my new spectrum analyzer
#ubitx
Nice job. It looks like all the bands except 20m are pretty good. I assume this was straight cw. I don't see any spurs. It would be interesting to see the same sweeps with an audio tone feeding the mi
Nice job. It looks like all the bands except 20m are pretty good. I assume this was straight cw. I don't see any spurs. It would be interesting to see the same sweeps with an audio tone feeding the mi
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Tim Gorman
· #65687
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RF power chain mods and improvements..
Andy, I've always used 450degF with my smd stuff and have never had a problem soldering anything. I don't use a pointed tip but one with a small flat on the end, a *very* small flat. Don't remember wh
Andy, I've always used 450degF with my smd stuff and have never had a problem soldering anything. I don't use a pointed tip but one with a small flat on the end, a *very* small flat. Don't remember wh
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Tim Gorman
· #61991
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not receiving messages
I am marked to get individual messages under Subscriptions. I show nothing from bitx20 in the spam folder at my email provider. The "No Email Deliveries" under "Last Unsuccessful Attempt" is what real
I am marked to get individual messages under Subscriptions. I show nothing from bitx20 in the spam folder at my email provider. The "No Email Deliveries" under "Last Unsuccessful Attempt" is what real
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Tim Gorman
· #61500
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not receiving messages
I am not getting any messages from the bitx20 group. My last message was #61157. Under "Most Recent Unsuccessful Attempt" it shows: "No email deliveries" Do I need to change something under the Subscr
I am not getting any messages from the bitx20 group. My last message was #61157. Under "Most Recent Unsuccessful Attempt" it shows: "No email deliveries" Do I need to change something under the Subscr
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Tim Gorman
· #61498
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Amplifier chain design - best practices
IMD can be caused by two things, saturation at high power and cross-over distortion near idle conditions. I suspect the high standing current prevents cross-over distortion which is why you get better
IMD can be caused by two things, saturation at high power and cross-over distortion near idle conditions. I suspect the high standing current prevents cross-over distortion which is why you get better
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Tim Gorman
· #59916
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UBITX...getting to legal ???
iz, 3rd order and higher IMD can occur in *any* stage in the RF transmission path. It can actually happen in audio stages but that only affects the quality of the audio, it doesn't generate RF interfe
iz, 3rd order and higher IMD can occur in *any* stage in the RF transmission path. It can actually happen in audio stages but that only affects the quality of the audio, it doesn't generate RF interfe
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Tim Gorman
· #59679
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2N2222A vs 2N3904 sourcing
Back in March, 2018 I tried building up an amp section using an HP mmic I have in the junk box. It worked very well on the desktop. Flat from 3Mhz to 30Mhz. No oscillation. I simply could find no way
Back in March, 2018 I tried building up an amp section using an HP mmic I have in the junk box. It worked very well on the desktop. Flat from 3Mhz to 30Mhz. No oscillation. I simply could find no way
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Tim Gorman
· #59435
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Simple spur fix
I don't think paralleling the filters will impact the nominal input impedance of each filter. If you have a SA and have something to generate a 45Mhz signal you could sweep the filters in parallel and
I don't think paralleling the filters will impact the nominal input impedance of each filter. If you have a SA and have something to generate a 45Mhz signal you could sweep the filters in parallel and
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Tim Gorman
· #59037
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Simple spur fix
Should the pad after the balanced modulator be changed to add more loss? That should be easy to do. tim ab0wr "ajparent1/KB1GMX" <kb1gmx@...> wrote:
Should the pad after the balanced modulator be changed to add more loss? That should be easy to do. tim ab0wr "ajparent1/KB1GMX" <kb1gmx@...> wrote:
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Tim Gorman
· #59036
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stone soup ingredient list, what bands and modes are usable
Allison, I agree with everything you have said here. I really don't have anything new to offer at this time. I've moved on to other, more pressing projects. Perhaps I'll get back to the ubitx as the w
Allison, I agree with everything you have said here. I really don't have anything new to offer at this time. I've moved on to other, more pressing projects. Perhaps I'll get back to the ubitx as the w
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Tim Gorman
· #59002
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Grounding shematic for a Metal Chassis, which is the right way to wire up?
Yep! That's the whole point of a single point ground! Run the negative lead from the radio to the battery! tim ab0wr "iz oos" <and2oosiz2@...> wrote:
Yep! That's the whole point of a single point ground! Run the negative lead from the radio to the battery! tim ab0wr "iz oos" <and2oosiz2@...> wrote:
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Tim Gorman
· #59001
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Grounding shematic for a Metal Chassis, which is the right way to wire up?
Respectfully, having fought noise problems in several different cars and trucks, dependence on the dash to provide a ground or even depending on the floor pan of the vehicle is a good way to introduce
Respectfully, having fought noise problems in several different cars and trucks, dependence on the dash to provide a ground or even depending on the floor pan of the vehicle is a good way to introduce
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Tim Gorman
· #58917
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stone soup ingredient list, what bands and modes are usable
Allison, The scope is perfectly usable when used as intended and you know what it is telling you. The known problems? I was the first to try adding an mmic after Q90 to help with making output more co
Allison, The scope is perfectly usable when used as intended and you know what it is telling you. The known problems? I was the first to try adding an mmic after Q90 to help with making output more co
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Tim Gorman
· #58908
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