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Hi Steve, Thank you for the information! I was wondering how one designed these as I wasn't finding any direct design tools online. The chart will be enough to get me started; I'll build it and do

Wow that is an amazing difference!? Next time I need one I will try to use this.? Sounds like the design is a bit more involved though. Thanks!

8 have never seen the videos and would appreciate if they were available again! Thanks ?

Like Dave mentioned, there is info in the old qrp group from the 25th anniversery NC-40 build... Here is what I wrote (message #14308): "I am running a 1n4007 in mine, works great. I am using Chuck's

If anyone has a project that needs an MV209 (40pF at 1V to 10pF at 9V) or an MV2101 (10pF at 1V to 5pF at 9V), I have some extras. But to be clear I'm not moving them from my spare stock to your spare

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 kHz."

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

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

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

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

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

What circuit did you use to test?

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

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

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

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

http://www.hanssummers.com/varicap/varicapdiode.html Not that particular part but useful info here. Plus a circuit to take some data.

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

Change cutoff to 6.1 MHz for 80M. Not quite as good as previous 40M filter. John KN5L

URL for filter design tool https://markimicrowave.com/technical-resources/tools/lc-filter-design-tool/