Re: Dummy load antenna


Karl Schwab
 

How about using Crickets at the convention?  Karl/KO8S

On Fri, Mar 11, 2022 at 3:54 PM KF5CSW <rehabnurse63@...> wrote:
Pardon me for my lack of intelligence beyond that of General Class license... I'd never be able to obtain Extra...
 
I would *love* to participate in the hotel room qrp activity at the convention this year (my first). I only see a hand drawn schematic of the  Ozark Con DL special. There's some blue text on that webpage (http://www.wa0itp.com/dlspecial.html). If it's supposed to be a link, it doesn't seem to be active.
 
I'm unfamiliar with the 50 ohm resistor used.  My first thought would have been a single 50 ohm resistor. But you have to dissipate a little heat, right? Then I started looking how dummy loads that are *not* intended to radiate at all are constructed. I found various diy dummy load resistors that involve anywhere from 4 to maybe 20 resistors run in parallel that would give 50 ohms. I could probably build that myself. I do see some kits available for this purpose, but they also contain some additional elements like a diode-capacitor rectifier for peak voltage measurements... where to connect the wire antenna part in those setups? I do see on some of the schematics that there are pins for RF and for ground.  Maybe connect to those? However, Those ones have a BNC male connector, which wouldn't work for that setup (see below).
 
Qrpme's Dummy Load Construction Set looks intriguing and might be a solution in itself. However, the provided connector in the kit is an RCA jack. At the time of the convention, the only thing I will have that works on 40m is my Icom 718 set to low power, and that uses a SO-239; I'm stuck with a piece of coax that has PL-259's at each end. I don't know if an adapter (RCA plug or BNC female) throws off my impedance.
 
If I made any technical mistakes in this post, please forgive me.
 
Thank you :)
John Vogel
KF5CSW
Roger's, AR
 

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