[Lowfer] SW, SIW, EAR this afternoon

[Michael Sapp]

Mike, Garry & JB & All:  A few captures this afternoon using my NW EWE antenna, 300 kHz LPF, and battery powered  2N3904 preamp to FT-817 on 185.3 and 188.83 dial frequencies...
 
 
WM and SIW  
 
https://www.dropbox.com/s/vdy65fqhnyeho3p/wmsiwf10.jpg?dl=0
 
 
EAR
 
https://www.dropbox.com/s/z9zxyli9um02x0e/earf10a.jpg?dl=0
 
 
Changes made to the 2N3904 preamp included going to .22uf input and output coupling caps (from 4.7uf) , changing the input resistor to 390 ohms to minimize input loading
when connected to 50 ohm load, and going from a grounded emitter to a 4 ohm emitter resistor with .22uf bypass to make Rc/Re  close to 100 gain factor.
 
https://www.dropbox.com/s/2dvq3ei2og91nd7/IMG_1067.JPG?dl=0
 
I also decoded 2E0ILY twice last night on 2200m using the 2N3904 preamp in a bench top rx converter arrangement with 3.0MHz IF instead of straight into the FT-817 at LF.
 
The rx converter avoids the input loss on LF with the FT-817 and does make a difference, but I am still surprised the FT-817 with a TXCO works are well as it does at
 
1750 and 2200 m bands...I’d say my high level converter holds a 3 or 4 dB edge, but for casual reception at LF/MF the pre-amped 817 works fairly well.
 
 
One interesting observation is I also changed the in/out coupling caps in my high level rx converter 2N5109 preamp.  Since I use the somewhat orthogonal EWE antennas with two different converters and receivers, I did notice a change in the other receive setup background noise level when going to the smaller .22uf caps in the first rx setup---so the two antennas share some energy, especially with decreasing frequency.  Changing to smaller .22uf coupling caps in the other converter further improved the level of local sinusoidal interference at 2200m and down.  Of course, there is some gain roll off on the preamps below 50 kHz, but not as much as I intuitively thought would occur..... Seems that capacitor impedance equation  SQR RT (R^2 + Xc^2) applies if I assume R something in the 50 ohm ball park....or whatever characteristic impedance circuit the input/output coupling C is used in.    That was a (really) useful lesson for me....
 
73, Mike wa3tts