Re: Damage to SMT version bitx40 from nearby transmitter
Raj,
Thanks for the clarification, and the opportunity to climb upon the shoulders of those who precede me.
Thomas W Noel
KF7RSF
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Thomas Noel <tnoel@...>
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#19115
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Re: Bitx40 review (video)
Peter, in the video you mention removing a cap in addition to the toroid from the VFO circuit when converting to a DDS VFO. Which cap did you decide to remove (I assume it would be C91)?
73, AL -
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Al Duncan VE3RRD
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#19114
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SolderSmoke Podcast 192 is available
SolderSmoke Podcast #192 FPM Rig, BITX Module Madness, HRO Al Fresco, Boatanchor Day, Mailbag
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SolderSmoke Podcast #192 FPM Rig, BITX Module
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Bill Meara
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#19113
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Re: Bitx40 review (video)
Ah yes, I see it now.? Thanks.
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Bill Meara
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#19112
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Re: Pop in speaker on key-up
Tnx for the help. I didn't use the right search terms.
I will dig up some of the older posts, but will prob. just live with it.
Once I have in metal case maybe it will clean up some.
My only issue
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kt4wo67@...
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#19111
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Re: Bitx40 review (video)
The blue RV1 is the bias set for the IRF. The drive is set by the preset R136 before the driver transistor.
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Raj vu2zap
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#19110
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Re: Damage to SMT version bitx40 from nearby transmitter
Thomas,
I would recommend you do both. The diodes may not take the all power from your other antenna.
Yes the two diodes in parallel are connected between pin 12 of k1 and ground. Both diodes should
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Raj vu2zap
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#19109
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Re: Bitx40 review (video)
Another nice video Peter.? Thanks.?? In your comment on the pot in the RF amp stage, I think you made the same mistake that I did: assuming that that pot was for setting the IRF-510 bias (as was
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Bill Meara
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#19108
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Bitx40 review (video)
There's not much in it that most people here won't already know, but a video review I've just uploaded could still be of interest.
Review: BitX40 7 MHz transceiver module
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Peter Parker
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#19107
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Re: Damage to SMT version bitx40 from nearby transmitter
Raj,
Thank you for the response. You confirm my fear that the danger of damage is real and present.
I am very much a beginner at this sort of work. I have excellent mechanical and soldering skills,
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Thomas Noel <tnoel@...>
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#19106
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Re: Damage to SMT version bitx40 from nearby transmitter
Thomas,
At pin 12 of K1 relay solder 2 4148 diodes in parallel but in opposite polarity. This will limit the receiver from getting high RF voltage.
Also if you cut the track between K1 pin 12 and
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Raj vu2zap
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#19105
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Re: Bitx 40 board.
Not really.
I would guess the confusion arises because there are two different inversions happening. The first is what you experienced with the DDS -- the frequency span is the same but TUNING is
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John Backo
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#19104
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Damage to SMT version bitx40 from nearby transmitter
How likely is this to happen? Bitx40 connected to 40M resonant antenna perpendicular to another antenna with a 100W transceiver running a Winlink gateway.
I fully expect front-end overload and nasty
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Thomas Noel <tnoel@...>
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#19103
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Re: Pop in speaker on key-up
Trip - KT4WO
The infamous BITX-Click has been well documented on this forum, but it was
mostly
some time ago.
There is a capacitor that couples the receive audio from the BFO mixer
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Arv Evans
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#19102
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Re: Pop in speaker on key-up
Trip et al,
It has been discussed before. Search for “PTT noise” or PTT transient”. Cause and solutions both simple (ignore it) and complex (Multi-transistor multi-relay switching schemes to
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Thomas Noel <tnoel@...>
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#19101
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Re: Pop in speaker on key-up
Trip,
I found that while I had my board sprawled all over my bench that the click on Xmit was real loud with all my cables crossing each other, when I got the wiring cleaned up and separated and the
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Joel Caulkins/N6ALT
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#19100
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Pop in speaker on key-up
Just to the controls hooked up...for testing. Upon key up I get a loud "pop" in the speaker.
I searched the group and didn't see this issue.
Ideas??
Trip - KT4WO
kt4wo67@...
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kt4wo67@...
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#19099
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Re: Bitx 40 board.
There is an excellent and easy to remember rule of thumb on sideband inversion.? Explained here: Sideband Inversion
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Sideband Inversion
Radio electronics blog.
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Bill Meara
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#19098
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Re: Bitx 40 board.
Hi John
I had a chance to try some testing with sideband inversion.
BFO = 11.9986 MHZ and VFO = 4.8486 MHZ this gives me a starting frequency
of 7.15 MHZ(RF = BFO - VFO). Set the encoder to increase
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Ken
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#19097
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Re: BitX40 Spectrum Output
Sure I'll do it now. Thanks.
Tom
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Tom Hurst
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#19096
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