TopBand: 2-wire beverages (part 2)
Lee Wells
leewells@lexmark.com
Wed, 26 Feb 1997 12:31:51 -0500 (EST)
de KT4ZX - Lee Wells - leewells@lexmark.com
Once I got home last night, I made a couple mods to the 2-wire
beverage box. When I opened up the box, I noticed that one ground
wire MAY have been shorting to the signal wires...I made sure this
was well insulated when I put it back together. The other thing I
did was add a 50 ohm terminating resistor that gets switched in to
the unused port. So about midnight I wandered back outside to
reinstall the box (the neighbors surely think I've lost it now!).
And now the results......
- 160 still doesn't have much of a F/B ratio. I finally
found one US station that would go up or down by a 2-3 S
units (on a Icom-745) when switching directions.
Europeans were still down in the mud, with no noticable
difference front to back.
- 40m is a different story!!! Listening to some broadcast
stations on 40 I was able to see a 20-30 db difference
(S9+40 to S9+20).
- 80m looked good too. I heard some US stations working a
TK6. Off the back (west) all I could hear was static, off
the front the TK6 was easy copy! The US stations also showed
a 3-4 S unit drop when switching directions.
- WWV on 5 MHz is 20db stronger off the back.
- WWV at 2.5MHz shows almost no difference (maybe 5 db)
front to back.
So I'm beginning to think the low frequency response of this thing
is way off! Does that mean I didn't use enough turns for the
transformers???? Or is this really a fair comparison since at 7MHz,
the beverage is somewhere over 3 wavelengths long.
Any ideas on whats going on here????
Thanks again....
--Lee
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
Sponsored by: Akorn Access, Inc. & N4VJ / K4AAA