On Wed, 26 Feb 1997 12:31:51 -0500 (EST) Lee Wells <leewells@lexmark.com>
writes:
>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
Lee, it sounds as if ur beverage is a bit too short for 160M and is
favoring the higher angles. Possibly a transformer problem too but if you
followed a standard design not too likely.
You dont mention ur QTH but from here in NH one wavelength appears to be
the absolute minimum for good EU performance. Two waves would be about
ideal for the real long haul into Zone 18, etc.
I wish I knew the electrical length of my 175' Slinky beverage but it
consistently out hears a 1 wave terminated wire version. I have a feeling
that it is somewhere in the 2 wave region...just a wild guess based upon
experience with a standard 1200' one at my old QTH. When I went to 2100'
everything suffered.
Im beginning to feel that my poor results with a 1 wave 2 wire was due to
excessive spacing and possibly the poor ground here....solid granite
8-14" down.
GL....Carl KM1H
--
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
|