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Re: Varactor Diode C Measurement
Chuck, On page 16 of http://transport.ece.illinois.edu/ece340f12-lectures/ece340lecture27-junccap.pdf there's an equation for the capacitance of a reverse biased diode Cj =? ?A/2 *
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Jerry Gaffke
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#505
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Re: Measuring Resonant Frequency of Traps
Don't forget the "noise bridge".? Here is a simple one that can be built out of junk parts: https://www.radioexperimenter.us/rm-1996-05/antenna-noise-bridge-detector.html It is a very useful and
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Dale Hardin KS4NS
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#504
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Re: Varactor Diode C Measurement
Gary,? What was the specified part? -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv
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Chuck Carpenter
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#503
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Re: Varactor Diode C Measurement
Jerry, the shape of the curve in fig 3 is typical of?junctions of non?"purpose built" diodes. (like that term). I've attached a set of curves from K7QO.? The curve at the bottom is a power diode.?
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Chuck Carpenter
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#502
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
Tangential note and thank you to Ray for enabling the "edit" feature for comments. Sure allows one ot revise embarrassing spelling errors and grammatical mistakes. Never did understand why Chuck did
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k6whp
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#501
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
Rob, Understand that. I coined the term "Baofeng Tech" -- originally defamatory -- mainly because there were a number of guys on a local SoCal repeater system who occupied commute time talking on
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k6whp
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#500
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Edited
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NanoVNA for Network Measurements
This is one of the great tools now available to all?for working with? project that you pump and signal into or receive a signal from?and finding out what is really going on.? The 11, 12 ports can
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Chuck Carpenter
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#499
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
I don't know about you guys but when I first got a Technician license 21 years ago (after passing 5WPM CW) and I was finally allowed to use a 2 meter HT I could not purchase a 2 meter HT for anything
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Rob <roomberg@...>
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#498
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Re: Si5351 output power
Loading the clock outputs with 50 ohms (such as a 6db attenuator) will make crosstalk and phase noise much worse. Hence the discussion here of cheap 74ACT and 74LVC series buffers to drive a 50 ohm
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Jerry Gaffke
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#497
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Re: Measuring Resonant Frequency of Traps
It's a Military/Viet Nam Era thing. "F---ing New Guy" meaning the newest arrival in a unit. Also, many, many thanks for the great ideas. I think with the availability and affordability of the antenna
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k6whp
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#496
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Re: Measuring Resonant Frequency of Traps
whats the FNG mean?
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Rob <roomberg@...>
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#495
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Re: Measuring Resonant Frequency of Traps
NOTHING beats a real antenna analyzer. Just my opinion. I bought a used MFJ259 for $100 ....twenty years ago and it has been THE "go to" tool for the local radio club and has been passed around so
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Rob <roomberg@...>
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#494
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Re: Si5351 output power
Hi Yes, generally it is a good idea to make the mixer see a constant load vs frequency. So a 6 dB pad will provide a higher return loss than 3 dB will. But given that the output power from a single
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Bo, OZ2M
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#493
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Re: Measuring Resonant Frequency of Traps
A Millen Antenna Bridge will give you both the R and Xc of an antenna. But a simple Heathkit Antenna Bridge will give you only the R of the antenna. These things date WAY BACK! And they have only
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Bob Macklin
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#492
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Re: Measuring Resonant Frequency of Traps
Some newer transceivers, like the Icom IC-7300, include a graphical SWR plot function. Put a dummy load on the other end of the trap and have the radio show you the swr plot. That might help some.
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Michael Maiorana
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#491
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Re: Measuring Resonant Frequency of Traps
Did we miss the part where William explains they are FNG Baofeng techs? Eric KE6US
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Eric KE6US <eric.csuf@...>
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#490
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Re: Measuring Resonant Frequency of Traps
Or, obviously, just a transmitter with an SWR meter (perhaps Diz's tandem match). But the single number representing SWR into an assumed 50 ohm antenna system is not nearly as informative as the two
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Jerry Gaffke
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#489
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Re: Measuring Resonant Frequency of Traps
Might not be a good idea to test the traps in isolation. The remainder of the antenna system can affect resonance.
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Jerry Gaffke
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#488
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Re: Measuring Resonant Frequency of Traps
Google "nanoVNA",? $50 for a vna good from khz to ghz. Display is teensy and thumbswitch is cranky, but performance is exceptional. Newer versions are coming out. Non-trivial for the neophyte, but
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Jerry Gaffke
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#487
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Re: Measuring Resonant Frequency of Traps
Connect the parallel resonant circuit in line with their transceiver input and tune for a null or connect it across the input and tune for a peak. You could also have them reconfigure it as a series
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Eric KE6US <eric.csuf@...>
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#486
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