Hi Rami,
I am also "forced" to use the FC40 and in reality I regret not having
bought the SGC-230 instead...
The FC40 seems to have only a limited impedance and reactance tuning
range and therefore is rapidly 'running out of breath" with more
demanding antenna systems.
As you will have found out, it is quite difficult to find an end-fed
wire length that it will tune all-band.
A 23m inverted L with goud ground system it will tune.
On my sailing boat it is really giving me a headache.I use a sloping
backstay wire as wire antenna, with a halyard running down from mast
top, sloping to port sisde aft, with heavy duty isolator through the
deck and 40 cm extra wire untill the FC 40. As RF ground I use wide
copper tape running to engine mass and also to an underwater bronze
strut underwater. Via copper tape also coupled to the stailess steel
lifelines that run on both sides of the boat, + 2 radials cut for 40m
and 2 cut for 20m.
I can only tune all band (and still miss bottom part of 80m) with
9.6m total wire length till FC40. 12.5 or 13m does not work.
The FC 40 is also very very sensitive to length even some distande
away from 1/2 waves.
I tried to insert a 1:9 Unun at bottom just before tuner, with 12.5m
wire. Works more or less but this is lossy.
Now why do you try to tune an OCF dipole? Do you mean installing the
FC40 AT the antenna, just where the 2 uneven dipole halves meet?
Normally the impedance there should be around 300 Ohms for most of
the usable bands (since normally a 1:6 balun + good choke is
installed there before running down coax).
The FC40 should be able to handle that 300 Ohms!
But why don't you justhook the FC40 at the end of the coax at your
transceiver, and install the normal 1:6 balun at the antenna? The
FC40 should easily tune-up the slight SWR you will find with and OCF
dipole on some bands.
Another idea: run down a twin lead (450 Ohms of 1/2 electrical wave
on lowest band, then a 1:1 current balun and this into your FC 40? I
would guess this would be a very losless system?
In a field situation like the Zambia, I would use 20m, 17m and 15m
simple wire vertical dipoles (no tuner needed) and maybe an 80m
horizontal loop, hanging at leats 10m high, fed with twin lead out of
corner, to a 1:4 balun at the tuner.
Jan
ON3ZTT
--- In YaesuTuner@..., "oh6bi" <oh6bi@...> wrote:
Hello All after long winter !
Yesterday I put my boat to sea and today goeing to summer
cottage with FT897 and FC40..
If you dont know about me, just read some earlier messages
from oh6bi in this group.
OK, last messages during autumn I told to start testing
FC40 and OCF dipole, yes I will do that.
During this winter I spent 3 months in Zambia (9J2BI)
and I didnt get good contacs to Europe with 23m long Wire.
I installed The Wire four times to different directions
to get better EU signals, but no good success, only some
QSOs to Europe, none to OH. JA and UA9 where the best.
Also local QRM and QRN where strong with The Wire.
After that I did some tests with 7 MHz deltaloop and that was much
better. QRN and QRM where lower and receiving signals better.
Unfortunately work was disturbing The Hobby and not enough
time for the loop. That means I will start this summer experiments
with 7 MHz Delta Loop.
You will see what happens..
By the way, does anyone have information how FC40 really works ?
I mean would be nice to build "universal control box" same way
as many has done with Icom AH4(and AH3, what I am using with
IC706).
Check in AH4 section from
AA7OL Niko Takahashi: "AH4 connetion to any Radio".
Best Regards and 73s de rami, oh6bi
