Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old May 25th 05, 04:51 PM
Lucky
 
Posts: n/a
Default Lowe HF-150 Antenna

Hi guys

It says in the manual that if the aerial selector switch is in the Norm
position the terminal long wire and 50 Ohm coax socket are *both active.
BUT, it also says the Whip socket, which is also the 50 Ohm coax socket, is
only active when the switch is in the Whip position.

What if you 2 antenna connected to the radio at the same time? One as a long
wire connected to the terminal and 2 small dipoles on the 50 Ohm socket. If
**both active when the switch is on Norm, how is the signal being
distributed to the radio?

I mean wouldn't this be a bad setup? 3 different antennas to the same radio?
I was switching the aerial selector to the Whip position when I wanted to
only use the dipoles. But then I wanted to use a long wire too cause certain
fequencies came in better with a lower noise floor with it and vice versa.
But it seems I can't switch to the long wire alone. The dipoles will always
chime in too.

If I switch to the Whip position,, I can use the dipoles alone but not the
other way around. So what do you suggest??


Also what I don't understand if switch is Attenuation position, it works on
both ant connections. But the Whip has a built in pre amplifier. So why
would you want to attenuate the pre amp?
It seems like a clumsy approach to me.

Thanks for any replies
Lucky






  #2   Report Post  
Old May 26th 05, 12:22 AM
RHF
 
Posts: n/a
Default

Lucky,
  #3   Report Post  
Old May 26th 05, 12:40 AM
Lucky
 
Posts: n/a
Default


"RHF" wrote in message
oups.com...
Lucky,
.
An Antenna Switch with Four Inputs an One Output
will be a more effective solution to your mulit-antenna
problem. Connect the Antennas to the Swtich and
connect the Switch to the Receiver.
.
Four Inputs to One Output Antenna Switches :
http://www.universal-radio.com/catalog/switch/2415.html
http://www.universal-radio.com/catalog/switch/1864.html
http://www.universal-radio.com/catalog/switch/0362.html
.
iane ~ RHF
. . . . .


Not a bad idea. Thanks! I could easily use the switch with my other rigs
too. But do these switches reduce gain or sensitivity at all?? Any
drawbacks?

Lucky


  #4   Report Post  
Old May 26th 05, 05:44 AM
Lucky
 
Posts: n/a
Default


"Dale Parfitt" wrote in message
news:aU9le.863$Pm3.686@trnddc08...

"Lucky" wrote in message
...
Hi guys

It says in the manual that if the aerial selector switch is in the Norm
position the terminal long wire and 50 Ohm coax socket are *both active.
BUT, it also says the Whip socket, which is also the 50 Ohm coax socket,

is
only active when the switch is in the Whip position.

What if you 2 antenna connected to the radio at the same time? One as a

long
wire connected to the terminal and 2 small dipoles on the 50 Ohm socket.

If
**both active when the switch is on Norm, how is the signal being
distributed to the radio?


Did you look at the schematic? It's pretty clear what is going on.

The intent is not to connect 2 different antennas at the same time- it is
to
give you the option of one or the other.
The attenuator and preamp are only connected to the coaxial socket. One
would use the preamp position with the short whip- rather than a preamp,
it
is a Z converter; making the whip+ preamp into an active antenna.
The attenuator position is to prevent strong stations from overloading the
150's wide open front end.

73,

Dale W4OP


Hi Dale

Yes I knew about the small whip and pre amp for portable use. I guess both
antennas can't be hooked at the same time even though it would have been
nice to be able to switch from the long wire to the coax socket like on the
R75.

I tried to improvise by using the "Whip" preamp position to cut off the long
wire and just use the coax but it seems I was not doing that. I was just
switching in the preamp on the dipoles and the long wire stayed active too.
I was under the impression since the preamp only worked in the Whip
position, it cut off the long wire connection at the same time letting me
choose between the two.

Under that impression I wondered why it wasn't vice versa. Did you
understand what I mean??

I guess I need a separate switcher like RHF suggested.

Thanks
Lucky



  #5   Report Post  
Old May 26th 05, 06:17 AM
RHF
 
Posts: n/a
Default

Lucky,


  #6   Report Post  
Old May 26th 05, 11:46 AM
Lucky
 
Posts: n/a
Default


"RHF" wrote in message
oups.com...
Lucky,
.
If the Whip Antenna's SO-239 Jack and Pre-Amp 'position'
work together; then you could use a Shielded Coax Cable
Loop Antenna instead of the Whip Antenna connected to
the SO-239 Jack and switch-on the Pre-Amp. Consider
to possibility . . .
.
iane ~ RHF
. . . . .


Well right now I'm doing that but using 2 small dipoles hooked up to the 239
jack and a 4:1 current balun. Why a loop instead? Do loops function better
with a preamp? I do know they null out noise much better then long wires or
dipoles.

Thank you
Lucky


  #7   Report Post  
Old May 26th 05, 12:45 PM
Lucky
 
Posts: n/a
Default


"RHF" wrote in message
oups.com...
Lucky,
.
If the Whip Antenna's SO-239 Jack and Pre-Amp 'position'
work together; then you could use a Shielded Coax Cable
Loop Antenna instead of the Whip Antenna connected to
the SO-239 Jack and switch-on the Pre-Amp. Consider
to possibility . . .
.
iane ~ RHF
. . . . .


But, if you put the antenna switch to "Norm", you can use the 239 jack
without the preamp according to the manual. This is what I used to use when
I first got it. I rarely used the long wire spring antenna terminal. So
again why a loop with the preamp??

I wonder what antennas most people use on their 150's? The wire spring
terminal or the coax socket and why??

Lucky


  #8   Report Post  
Old May 26th 05, 04:57 PM
Pete KE9OA
 
Posts: n/a
Default

I use my '150 with the high impedance input, using a Radio Shack air core
loop antenna. My reason for this is so the input circuit doesn't load down
the loop............this way, I can take advantage of the unloaded Q of the
antenna. This provides a sharper tuning characteristic.
The preamp is good for very short antennas. Since it is a broadband preamp,
it sees many tones (signals). It has a relatively low dynamic range; its
multitone response is not very good. The result is that signals far removed
from your desired receive frequency can drive the preamp into gain
compression if their level is high enough.
There is another complication here........it doesn't have to be just one
strong signal. Several medium level signals, if their integrated (combined)
power is high enough, can also drive the preamp stage into gain compression.
There are two results that I know of that can happen. First of all, the
amplifier can appear to not have any gain at the desired frequency, and
second, since the distortion of the amplifier rises at the 1dB compression
point, signals can appear at different points on the tuning dial where they
are not supposed to be.
An example of this is with my AOR-7030. In the Chicago area, if I have a
long wire connected and the whip amplifier is engaged, I can hear MW
stations in the 15MHz range.
If you thing of the absence of bandwidth limiting in the same manner that
you think of the aperture of an optical system, things become clearer. If
you were to connect a sensitive RF power meter to a long wire antenna and
compare the power levels of broadband response vs bandwidth limited response
(preselector), you would see a lower level of integrated RF power with the
bandwidth limited response. This is the reason that receivers with input
filtering ahead of the 1st stage perform better than receivers with a wide
open front end. There are exceptions such as the Racal 6790, the WJ
receivers, the AOR7030, and other receivers in the "premium" catagory, but
even these units would perform better with some sort of preselection.
My definition of preselection can be either a tunable form or fixed tuned
lowpass, highpass or bandpass circuits.

Pete

"Lucky" wrote in message
...

"RHF" wrote in message
oups.com...
Lucky,
.
If the Whip Antenna's SO-239 Jack and Pre-Amp 'position'
work together; then you could use a Shielded Coax Cable
Loop Antenna instead of the Whip Antenna connected to
the SO-239 Jack and switch-on the Pre-Amp. Consider
to possibility . . .
.
iane ~ RHF
. . . . .


But, if you put the antenna switch to "Norm", you can use the 239 jack
without the preamp according to the manual. This is what I used to use
when I first got it. I rarely used the long wire spring antenna terminal.
So again why a loop with the preamp??

I wonder what antennas most people use on their 150's? The wire spring
terminal or the coax socket and why??

Lucky



  #9   Report Post  
Old May 27th 05, 01:12 AM
RHF
 
Posts: n/a
Default

Lucky,
  #10   Report Post  
Old May 27th 05, 02:15 PM
Lucky
 
Posts: n/a
Default


"RHF" wrote in message
oups.com...
Lucky,
.
The Coax Cable {Shielded} Loop Antenna will have a
relative 'small' size an therefore a smaller signal
level; but the relative noise level will be reduced
much lower then the signal level (greater noise
reduction).
.
The Coax Cable {Shielded} Loop Antenna can be rotated /
positioned to help 'tune-out' your local noise sources.
.
The Coax Cable {Shielded} will usually have a better
Signal-to-Noise Ratio then many other larger antennas.
.
The Pre-Amp can be used to boost the lower signal
levels of the Loop Antenna to Hear Radio Signals
that may not be hear with other Antennas due to the
higher noise levels present when using the other
Antennas.
.
.
Two (2) Coax Cable {Shielded} Loop Antennas
for Shortwave All Band Coverage.
.
A single 25 Foot piece of RG8 Coax Cable with PL-259
Plugs on each end can be made into two separate Coax
Cable Loop Antennas :
Cut into a 9 Foot and 16 Foot sections.
.
= Thirteen Foot (13') Loop Element with a Four Foot
(4') Diameter and a Three Foot (3') Feed-in-Line for
a Total Length of 16 Feet. This Thirteen Foot (13')
Coax Cable {Shielded} Loop Antenna is roughly 'cut'
for the 49m Shortwave Band with good coverage across
the 75m, 60m, 41m, and 31m Bands.
.
= Six Foot (6') Loop Element with a Two Foot (2')
Diameter and a a Three Foot (3') Feed-in-Line for
a Total Length of 9 Feet. This Six Foot (6') Coax
Cable {Shielded} Loop Antenna is roughly 'cut' for
the 22m Shortwave Band with good coverage across
the 31m, 25m, 19m, and 16m Bands.
.
Sizing the GreerTech Coax Cable {Shielded} Loop Antenna
for the Shortwave Bands :
http://www.greertech.com/hfloop/charts.html#SWL%20CHART
.
.
RG8 'type' Coax Cable "In-Door" Loop Antennas :
.
* Coax Cable [Shielded] Loop Antennas {GreerTech}
http://groups.yahoo.com/group/Shortw...a/message/1625
.
* Tuning the GreerTech [Coax Cable] HF Loop Antenna
http://groups.yahoo.com/group/Shortw...a/message/1730
.
* Loop Antenna -or- Active Loop Antenna ? ?
http://groups.yahoo.com/group/Shortw...a/message/1394
.
.
iane ~ RHF
. . . . .


I have built my own loop but it's way to big and I have to downsize it. I
used like a 12Ft copper coil with a 1/2" to 5/8" ID
I then bought a 8 Ft by 1" length of PVC tubing and cut side holes the size
of the coil OD or a little bigger on top and midway. Then after getting the
coil as round as possible, I slid it thru the PVC holes I made. I used a
small wooden round peg inside the ends of the copper coil for separation.

I picked a large air variable capacitor off Ebay and hooked up the coax
using the shielded method from here and from other sites.
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9868

This page had good info I used for building one but I made mine round not
square.
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9868

And here is great resources for building your own loop:
http://www.dxzone.com/catalog/Antennas/Loop/

I'm going to trim this loop down and hook it up to the 150's socket and put
the switch on "Whip" for the pre amp to kick in. I also have a couple round
pieces of metal that you find in lamp shades to keep them round. They are
usually on the top and bottom part of the lamp shade.

They look and feel great for making a small desk side loop and you can
choose the size you want from a selection from thrift shops that sell old
lamps and shades. One shade can make 2 loops.

I might make a new one but using a smaller air cap and a good rotating stand
for it. I'd pick up a small electric remote control rotator and leave the
loop on the terrace and control it from the room. They are not expensive.

Thanks for good links RHF. They help give me more ideas so I can experiment.

Lucky






Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
FA: VHF / UHF Antenna Assortment - starting at $5.00 Les Wilson Swap 0 March 7th 05 01:09 AM
Discone antenna plans stryped@hotmail.com Antenna 13 January 14th 05 11:51 PM
Yaesu FT-857D questions Joe S. Equipment 6 October 25th 04 09:40 AM
LongWire Antenna Jim B Shortwave 5 March 2nd 04 09:36 AM
EH Antenna Revisited Walter Maxwell Antenna 47 January 16th 04 04:34 AM


All times are GMT +1. The time now is 11:11 AM.

Powered by vBulletin® Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2004-2017 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017