[Mobile-Portable] Screwdrivers and whips
N1KHB at aol.com
N1KHB at aol.com
Sat Jan 18 18:49:07 EST 2014
Randy,
Maybe you lost the whip closer to your destination than you thought
which might be an explanation as to why reception was still good along the
trip. Just a thought.
Sonny N1KHB
In a message dated 1/18/2014 6:32:33 P.M. Eastern Standard Time,
n5wv at comcast.net writes:
Hello Group , I had only used Hustler HF antennas while mobile and had
good results. Then went to a Scorpion SA 680 and had better results. Last
summer I purchased the American Red Cross Ford Excursion ECRV 4707 from the
Houston chapter. Most equipment was left intact . It has a SGC HF tuner and
whip system installed. The whip is about 102 " and perfect for 10 meters. It
does great on 10 to 15 but slacks off compared to the Scorpion. But its
easier to install. I had a $500.00 L mount fabricated to mount the big heavy
Scorpion on. Had it done first class , powder coated , etc. There is just so
much more receiving with a Scorpion type antenna so it does better on the
lower bands. For instance , I mainly listen. When I first bought the
Scorpion I purchased a Radio Shack 102 " whip for it. About a month later I got
back home from a trip and the whip was gone. The whip had broken off just
above its lug where it screws into the top of the screwdriver antenna and I
had not hit anyth
ing at all. After I removed the broken piece and after closer inspection
the metal had small bubbles in it from a bad mix or temp problem. I found
one of the old Antenna Specialist 108 " land mobile whips to replace it with.
The RS whip broke off at some point while I listened to 20 meters the
entire trip. I know it was on when I left because I always look at it. But
throughout the entire trip listening to 20 meters , I still had great signals
and did not notice any change in signal strength. Im sure there was some
signal strength loss . I even have a 7 " LCD tv atop my dash showing the IC
7000's display. But there was no drastic loss of signal. The SA 680's coil
and tubing was still receiving a good signal with no whip atop it. To add a
bit more insurance I added a Antenna Specialist spring between the SA 680
and 108 " whip. This takes the pressure of the lug somewhat and moves it to
the springs connecting part. So the bigger the antenna , the better it
receives. Have a nic
e weekend , Great group here. Randy N5WV
----- Original Message -----
From: "K0DAN" <k0dan at comcast.net>
To: "Mobile-Portable Reflector" <mobile-portable at mailman.qth.net>
Cc: iam at pmug.org
Sent: Saturday, January 18, 2014 11:01:04 AM
Subject: Re: [Mobile-Portable] Screwdrivers and whips
I did the same thing (whip + tuner). Had a lot of fun (mostly higher than
14
Mhz) and made a lot of contacts. But missed out on a lot also (mostly
lower
than 14 Mhz).
I am no longer mobile on HF but if I were to do it again I would
definitely
come up with a screwdriver design, and follow the guidelines on the K0BG
site http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12686
Have fun.
73
dan
k0dan
-----Original Message-----
From: David
Sent: January 18, 2014 00:17
To: Mobile-Portable Reflector
Subject: Re: [Mobile-Portable] Screwdrivers and whips
You are right!
I wasn't wise. I should have done my antenna efficiency studies BEFORE I
spent all that time and energy on the whip & tuner installation. BUT,
going back to the screwdriver cured the problems.
David
W7DBH
** The K0BG site is like a Handbook for HF mobile operations. Whether or
not
** you believe an efficient HF mobile station can be built on-the-cheap,
you
** are sure to find some good tips and practical info of various
** installations here.
**
** My own experience is that the ~108" whip with auto tuner is relatively
** stealthy (as stealthy as a 108" whip can be), but , even when installed
** high
** up, has poor radiation efficiency on freq's below about 14 Mhz. The
tuner
** will make the transmitter happy but a lot of energy is being lost into
the
** ground and vehicle chassis, and not going into the ether where it
belongs.
**
** Of course you can make contacts at 40M and 80M (even 160?!?) with a
whip,
** but the reality is a tuned antenna with an excellent vehicle ground
** distribution (and no noise) will give you 3-6 dB or more radiation
** efficiency.
**
** As with all things, your mileage may vary.
**
** http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12686
**
** 73
** de k0dan
**
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--
David B.
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