Topband: FT8 Observations

[David Olean]

   Hi Mike and all who responded.

     I guess I was just underwhelmed at what I could accomplish on FT8 
vs CW on 160.  I figured it would open up a whole new level of rare 
countries and places that were now workable to me. Working Kazakhstan on 
160 CW from my location is difficult, but doable on some nights in the 
winter. On FT8 I hear UN1L often, but I can never work him after many 
days of trying. I started out with 90 watts and ended up with 900 watts 
output, but never a response from him. I guess 160 is a special case 
where achieving a good receive noise level is very difficult.  FT8 must 
be a huge improvement for those, as you said, with few radials and 
smallish vertical radiators as their sole antenna. The extra 5 or 6 dB 
must be the difference of night and day for limited space or limited 
antennas in general.  It sure has fostered much activity on 160 with 
calls that are mostly unfamiliar to me.  I have worked a few regulars on 
FT8, like YO3APJ, and they seem to hear just fine. Unfortunately I am 
not QRV on other HF bands to try out FT8 there! I suspect the ALLIGATOR 
SYNDROME is not as evident on the higher HF bands.

On another subject, I ran out of room on my six position receive 
beverage coaxial switch. I had seven beverages, and one was not hooked 
up as a result.  I also have not been using diversity reception even 
though I am using a K3. So I finally worked out a plan to make a new 
switching box. It consists of two Grayhill 12 position rotary switches.  
The two switches have a set of the 12 positions wired in parallel 
between the two switches and each position connects to a rx input jack 
on the back, while the common terminal for each switch goes to the main 
rx jack or the diversity rx jack on the K3.  The 12 inputs are "F" 
fittings on the back of the switch box. I worried that the isolation 
would be poor, but it checks out at 55 to 65 dB on 160 and 80 meters. 
VSWR is pretty good too even with all the insulated wire used. I did not 
even try wiring it with coax! One switch selects any of 12 beverage 
antennas for the main receiver, while the second switch selects any of 
the beverages for the diversity receiver. It works very well and I 
wonder why I did not do this a long time ago. In the first evening I saw 
a huge improvement using diversity and it was nice having all the wires 
available too!  Too bad it won't get much use until next fall and winter!

73

Dave K1WHS


On 4/23/2018 3:50 PM, Mike Waters wrote:
> Hi Dave,
>
> I think it's safe to say that you're running Beverages in a very quiet 
> location, and the hams that can't hear you are not. What is more, they 
> might have a 20 over 9 noise level and are running non-directional 
> antennas (such as verticals with no radials or low dipoles).
>
> 73, Mike
> www.w0btu.com <http://www.w0btu.com>
>
>
> On Mon, Apr 23, 2018, 10:36 AM David Olean <k1whs at metrocast.net 
> <mailto:k1whs at metrocast.net>> wrote:
>
>     I have been playing around with FT8 on 160M and am a bit puzzled.
>     I have
>     made plenty of contacts, but with many stations, it seems to
>     require an
>     inordinate amount of power to get their attention, or they do not
>     respond at all. I also have noted that I can hear in a 2.8 kHz
>     passband,
>     signals that register from -12 to -17 dB. About the weakest that I
>     see
>     is a bit more than -20 dB. Does this mean that FT8 is only a few dB
>     better than CW?  I have my time set accurately and I try to place
>     my TX
>     signal away from whomever I am calling on a clear spot on my
>     waterfall.
>
>     Some stations are easy to work, and I have worked across the country
>     (FN43 to a CM grid) running just 1 watt. It just seems that there are
>     many stations that are not hearing much, but are making plenty of
>     noise.  Am I wrong?
>
>     I am working on cleaning up my 160 setup and have 8 beverages running
>     and they are all pretty quiet now that I installed plenty of ferrite
>     chokes around on the RG-6 feed lines.  I am looking forward to
>     next fall
>     and winter.
>
>     73
>
>     Dave K1WHS
>
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