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Re: 60 Meter homebrew rig IF frequencies
For 60 meters there are channel bandwidth requirements.
"Amateurs are permitted to operate on five frequency channels, each having an effective bandwidth of 2.8
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hwstar
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#9523
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Re: How good is the 1N4004 diode as a varactor
I'm assuming you've seen this Doug, in the old QRP-Tech group?
/g/qrp-tech/topic/1n4004_vs_mv209_tuning_range/6523696
Dave
AA7EE
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Dave AA7EE
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#9522
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Re: 1W and 5W build guides
If I put a keyer into a project, I use the one that Diz used in the 1W and 5W series.
It is the same keyer for both W's, just a different output on power up.? One did the 1W and the
other did the 5W
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chuck adams
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#9521
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Re: How good is the 1N4004 diode as a varactor
Hans provides a circuit to measure its varying capacitance. Of course you can also install candidate diodes into your vfo that may be easier.
I realize in the old days folk sought a huge range. But
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Curt
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#9520
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Re: How good is the 1N4004 diode as a varactor
Please ignore my last post. I wish these things could be edited after posting, but it doesn't work that way here! I was forgetting the influence of the 270pF cap connected to pin 6 of the 602. My
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Dave AA7EE
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#9519
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Re: How good is the 1N4004 diode as a varactor
I have no experience with the 1N4004 as a varactor, but I did use a 1N4001 as one in a simple NE602-LM386 DC receiver on 40M. The inductor was 3.1?H (27 turns on a T50-7). With a voltage span of
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Dave AA7EE
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#9518
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Re: How good is the 1N4004 diode as a varactor
What circuit did you use to test?
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Doug Hendricks
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#9517
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Re: How good is the 1N4004 diode as a varactor
Thanks for the info.? Very interesting that a 5mm red led works so well.? I'm going to do some testing.? ?Again, I appreciate the help.? Doug
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Doug Hendricks
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#9516
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Re: 60 Meter homebrew rig IF frequencies
In my BITX40 I used the VFO to switch USB/LSB for digital, so high side and
low side. Worked great.Could I hear the difference? Yes. The filter skirt
was different. Was it equally usable? You bet it
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Ryan Flowers
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#9515
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Re: 60 Meter homebrew rig IF frequencies
But i think it? it is easy because will you hear the difference? I believe not.
I cant give exact figures because I do not have the precission equipment to measure it. Yes the roll off slope is
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Kees PE7ST
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#9514
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Re: How good is the 1N4004 diode as a varactor
Hi Doug,
One normally doesn't run a varactor down to 0 volts (as Han's chart showed), but at minimum 1 volts. I tested two brands of rectifier--1N4003 and 1N4007.? The 4003 at 1V was 10.6 pF and at
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Steve Ratzlaff
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#9513
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Re: How good is the 1N4004 diode as a varactor
http://www.hanssummers.com/varicap/varicapdiode.html
Not that particular part but useful info here. Plus a circuit to take some data.
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Curt
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#9512
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How good is the 1N4004 diode as a varactor
What is your experience with using the 1N4004 diode as a varactor in tuning circuits?? How does it compare to the MV209? In the same circuit, what is the comparison between the 2 diodes in tuning
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Doug Hendricks
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#9511
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Re: QRP TX LPF illustration
Change cutoff to 6.1 MHz for 80M. Not quite as good as previous 40M filter.
John KN5L
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John KN5L
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#9510
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Re: QRP TX LPF illustration
URL for filter design tool
https://markimicrowave.com/technical-resources/tools/lc-filter-design-tool/
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John KN5L
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#9509
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Re: QRP TX LPF illustration
One way is using a filter design tool for a start,
LC Filter Design Tool
Select Lowpass, Elliptic, Shunt First, Order 5, cutoff 10 MHz, ripple 0.10, and stopband (dB) 37
Place calculated values into
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John KN5L
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#9508
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Re: QRP TX LPF illustration
Hi Goody,
For my example I used an existing LPF and simply used each inductor to calculate what resonating cap worked at the 2nd and 3rd harmonics and picked the closest standard value cap to use.
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Steve Ratzlaff
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#9507
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Re: 1W and 5W build guides
Thanks Chuck!
I may celebrate and build my Organic 5W CW Transceiver Kit for 40m finally...
I have an extra PCB and keyer chip in case I screw up.?? But just so others know - the keyer chip and
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Daniel KK4MRN
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#9506
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Re: QRP TX LPF illustration
I have a homebrew 80m CW rig I built 20 years ago that was out of spec and
I'm re-doing the final PA and LPF. Did you use an online calculator to
determine the values? I'd like to try this harmonic
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Anthony Good
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#9505
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QRP TX LPF illustration
We're all aware of the current FCC regs for harmonics and spurious outputs from a transmitter needing to be -43 dBc or greater below the fundamental output. Here's a 40 M LPF with the original
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Steve Ratzlaff
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#9504
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