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Date
Re: Changing out L5 & L7 in UBitX for Spur Fix
Scrape off the toplayer of the underlaying trace and solder them there. Works fine. Rob PA0RBL
By Rob Bleumer <Bleumer@...> · #62913 ·
Re: Having fun with uBITX
I have not yet tried to trace the signal path or a different microphone.?? Output power varies by band.? Strangely, it is lowest on 40M and 80 M, at 3-4 watts.? On 30M the power increases to over
By Woody <mailme@...> · #62912 ·
Re: Tracing receive signal for low signal
Thanks Evan I was not understanding that but got it now.? Appreciate all the great info and ideas/diagnostics here. TP17 at 11.99 or so I could get a tone 480mv gave .1v p-p TP16 same freq at 50mv
By Dave Space · #62911 ·
Re: Having fun with uBITX
Woody Did you every science out why the power seems low? Have you tried an alternate mic?
By _Dave_ AD0B · #62910 ·
Re: 7.277 Anyone
Too bad Evan. Your loss.
By _Dave_ AD0B · #62909 ·
Re: Changing out L5 & L7 in UBitX for Spur Fix
Your question made me go back and look at the picture.? L5 looks correct, as it is in the circuit as was the original (L5 and C215 in series with the filter).? L7 is directly connected to T4,
By Evan Hand · #62908 ·
Re: 7.277 Anyone
I tested with an RF Explorer SA and found that I had the harmonic issue on 40m, even on ssb.? I did not see the issue on 20m or 10m.? I have not had any success with those bands, mostly due to
By Evan Hand · #62907 ·
Re: Tracing receive signal for low signal
Dave, By the time the signal from the antenna gets to TP17, it has been converted to the audio on a 12mhz carrier.? Said another way, the signal by now has been converted to 12mhz +- the audio tone,
By Evan Hand · #62906 ·
Re: Tracing receive signal for low signal
AT 60mV you should a really loud sound from your speaker. Check all the resistors and report on DC voltages at the audio transistors. Raj
By Raj vu2zap · #62905 ·
Re: Tracing receive signal for low signal
TP 16/17 should be around 12 Mhz regardless of the frequency setting on th ubitx ...all else is filtered out by the 12 Mhz crystal filter Jim
By jim <ab7vf@...> · #62904 ·
Re: Tracing receive signal for low signal
Injecting 1khz tone 2.4v at pin 3 of q71 (should feed into q72 and q73) produced .1v p-p
By Dave Space · #62903 ·
Re: Tracing receive signal for low signal
Also interesing at the base of Q71 injecting 1khz signal at 60mv gave a .1 mv peak to peak signal but I could not hear any tone on the speaker.? It wasn't until injecting 300mv could I faintly hear
By Dave Space · #62902 ·
Re: Tracing receive signal for low signal
I checked the boards solder joints with a magnifying glass but it's really hard to tell.? probably need to find a way to test specific suspect points. I tried to check the toroids in the load pass
By Dave Space · #62901 ·
Re: Tracing receive signal for low signal
K3 pins 12 and 14 get a tone for continuity. Tp21 shows 10.85k ohms to ground.
By Dave Space · #62900 ·
Re: Quick question
The Koss cs100 has an electret element and works well. I have one that I have used. Someone else on this board put me on to it. They are now about $20, but not long ago were much cheaper.
By Randy W5ZJ · #62899 ·
Re: Tracing receive signal for low signal
Sorry that was for Q70
By Dave Space · #62898 ·
Re: Tracing receive signal for low signal
Q&0 pin 1 is 0.65v pin 2 - 0 volts pin 3 1.7 v Pin1 seems lower than the 1.3 expected in the diagnostic manual and pin 3 seems higher which was supposed to be 0.2v
By Dave Space · #62897 ·
Changing out L5 & L7 in UBitX for Spur Fix
just desoldered L5&7 to get ready for the placement of the SMD inductors.? From the image I can see where to solder the inductors to where the toroids were but can¡¯t see where to solder the other
By Guy WB7SZI <sgbridge@...> · #62896 ·
Re: Tracing receive signal for low signal
Also FYI just checking maybe not such a great deal on my scope the signal generator definitely has some differences compared to volt amplitude. I checked at 60hz AC volts with my multimeter and when I
By Dave Space · #62895 ·
Re: 7.277 Anyone
Evan: Maybe...maybe not. My ?BITX is legal on 80M and 40M, and spot on for 20M, so I can use it on two bands and be within spec. Right now, 20M is out. Jack, W8TEE
By Jack Purdum <jjpurdum@...> · #62894 ·