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Old January 5th 05, 03:44 AM
 
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Default DX-160: Preselector or 9:1 transformer

Hi--

I have a Realistic DX-160 in very nice conditiion I bought about 10
years ago (for $15!). My current living situation in Los Angeles no
longer affords me the luxury of an outdoor antenna, so I am using 40
ft. of 16 gauge copper speaker wire running along the ceiling moulding
as my antenna.

(ALSO: the DX-160 is in the same room with a lot of other electronic
equipment: computer, TV, stereo, audio recording equipment, mixer,
etc.)

I've read a lot in this newsgroup about modifying the DX-160, but as my
radio engineering skills are in their infancy, I've decided on
improving my antenna situation. It seems preselectors or the 9:1
matching transformer have favorable reviews here but I'd lke to know:

1) The DX-160 has an Antenna trim knob, so is a preselctor redundant?
2) The 9:1 matching impedance transformer is intriguing, but can they
be found/purchased already built?

Thanks in advance for any input!

SWS


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Old January 5th 05, 04:25 AM
Jeff
 
Posts: n/a
Default


wrote in message
ups.com...
Hi--

I have a Realistic DX-160 in very nice conditiion I bought about 10



1) The DX-160 has an Antenna trim knob, so is a preselctor redundant?
2) The 9:1 matching impedance transformer is intriguing, but can they
be found/purchased already built?

------------------------------------------------------------------------------

The trim knob is just a variable capacitor, which is somewhat what
the preselector is. The preselectors also use inductors in combo with the
variable cap. for the various bands. Personally Id use an MLB (matching
xformer) This will keep the input impedance to the radio fairly constant
around 50-70 ohms from your antenna. The better the impedance match
the more current will flow from the antenna to the radio. They have ready
made ones, I have a Watkins MLB that I dont use anymore if you are
interested.


Jeff


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Old January 5th 05, 05:40 AM
Howard
 
Posts: n/a
Default

On Wed, 05 Jan 2005 03:25:13 GMT, "Jeff"
wrote:


wrote in message
oups.com...
Hi--

I have a Realistic DX-160 in very nice conditiion I bought about 10



1) The DX-160 has an Antenna trim knob, so is a preselctor redundant?
2) The 9:1 matching impedance transformer is intriguing, but can they
be found/purchased already built?

------------------------------------------------------------------------------

The trim knob is just a variable capacitor, which is somewhat what
the preselector is. The preselectors also use inductors in combo with the
variable cap. for the various bands. Personally Id use an MLB (matching
xformer) This will keep the input impedance to the radio fairly constant
around 50-70 ohms from your antenna. The better the impedance match
the more current will flow from the antenna to the radio. They have ready
made ones, I have a Watkins MLB that I dont use anymore if you are
interested.


Jeff

I agree with Jeff and suggest that if you don't want to homebrew your
matching transformer that you look at the ICE 180A. You can view this
at:
http://www.arraysolutions.com/Produc...age%20Matching

There are other out there, however I've found this one::
1) seems to have more positive user reviews than other models
2) has worked quite well for me making me a satisfied customer
3) versatile as it will match 6:1, 9:1, 12:1 and 16:1 so you can
experiment with which value works best for you.

Another option is the PAR end-fed antenna which comes with a 9:1
matching transformer that can be configured in one of two ways in
respect to primary and secondary ground. It comes with 45 feet of
flex-weave wire which is very flexible and easy to work with. You
can check out this antenna at:
http://www.universal-radio.com/catalog/sw_ant/2205.html

Quadra - I too live in LA and empathize with you regarding not being
able to put up an outdoor antenna. Another thing you might do is
install the antenna in a different room than your electronic gear and
use coax from the antenna to the radio. It probably won't remove all
your household noise but should give you some reduction. If you feel
you need further assistance drop me an e-mail and I'll try to give
more assistance.

Enjoy the radio,
Howard


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Old January 5th 05, 05:58 AM
 
Posts: n/a
Default

Howard--

Thanks for the info--I'll do some reading up on both the of those
options.

One thing is puzzling me, though: the DX-160 has no coax input--only
"screw-type" terminals. So I'm guessing that some other adapter is
needed in addition to the transformer?

Thanks for the help...!

SWS

  #6   Report Post  
Old January 5th 05, 01:23 PM
Merwin Dooley
 
Posts: n/a
Default

Try this.
http://www.grove-ent.com/WR0130.html

1) The DX-160 has an Antenna trim knob, so is a preselctor redundant?
2) The 9:1 matching impedance transformer is intriguing, but can they
be found/purchased already built?

Thanks in advance for any input!

SWS



  #7   Report Post  
Old January 5th 05, 02:29 PM
RHF
 
Posts: n/a
Default

QUADRA,
..
Consider an "Around-the-Room" (Ceiling) Loop Antenna,
or an "On-the-Wall" Loop Antenna as an INDOOR Antenna
to use with your RadioShack "Realistic" DX-160 Receiver.
..
The Loops will generally be about Forty Feet plus
for an Around-the-Room (Ceiling) Loop Antenna, or
Thirth-Six Feet plus an On-the-Wall Loop Antenna.
..
1. Use Hook-Up Wire for the Antenna Wire Element.
RadioShack Catalog # 278-1225
Sixty Feet of Stranded #20 AWG Insulated Wire
..
2. Use a 'piece' of 300 Ohm TV Twin Lead as the
Feed-in-Line from the Loop Antenna to the Terminals
on the back of the DX-160.
RadioShack Catalog # 15-1174
Two 20 AWG Stranded Copper Conductors
Insulation consists of Inner Low-Loss Foam Insulation
and Outer Covering of Heavy-Duty Polyethylene
..
IMHO - Using the RadioShack DX-160 with a small size
(short length) "In-the-House" Loop Antenna; that using a
Matching Transformer and Pre-Selector are not required.
..
READ - Indoor Antenna & Lead-In = Hook-Up Wire / TV Twin Lead
http://groups.yahoo.com/group/Shortw...nna/message/75
..
READ - Try "In-Door" {Inside-the-House} Antennas First before . . .
http://groups.yahoo.com/group/Shortw...a/message/1036
..
READ - Looking for a "Silent Antenna"
Consider a {Shielded} Loop Antenna
http://groups.yahoo.com/group/Shortw...a/message/1008
..
READ - A 'look' at three MFL Antenna Turners / Pre-Selectors
http://groups.yahoo.com/group/Shortw...na/message/980
..
READ - Two InDoor "Hidden" SWL Antenna Ideas
http://groups.yahoo.com/group/Shortw...na/message/209
..
READ - The Carpet Loop Antenna
[ Sizing the Loop and Choosing the Cable ]
http://groups.yahoo.com/group/Shortw...na/message/292
..
..
iane ~ RHF
..
All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram"
http://groups.yahoo.com/group/Shortw...na/message/502
Some Say: On A Clear Day You Can See Forever.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
[ With the an AM/MW - FM - SWL Antenna of your own making. ]
..
..

  #8   Report Post  
Old January 5th 05, 03:41 PM
RHF
 
Posts: n/a
Default

QUADRA,
..
READ - The RadioShack Realistic DX-160 Receivers
- - - - - USERS - ANTENNA - SURVEY - - - -
..
SOURCE - Newsgroups : Rec.Radio.Shortwave
From: *t (David Neece)
Date: 1998/05/20
Subject: RadioShack Realistic DX-160 Users: Antenna Survey
..
RadioShack Realistic DX-160 = http://tinyurl.com/4qzlc
http://groups-beta.google.com/group/...75e180bc56f5a4

..
..
RadioShack Realistic DX-160 and Eavesdropper Antenna Installation
SOURCE = Newsgroups: Rec.Radio.Shortwave
From: Charlie Meyer *t
Date: 1997/12/31
Subject: Advice: Realistic DX-160 and Eavesdropper Antenna Installation
http://groups-beta.google.com/group/...09bd848888d809

..
RadioShack Realistic DX-160 - Home Made Antenna Questions
SOURCE = Newsgroups: Rec.Radio.Shortwave
From: *m (Christopher A. King)
Date: 1999/09/10
Subject: Home Made Antenna Questions
http://groups-beta.google.com/group/...11f88ff0220628

..
..
iane ~ RHF
..
All are WELCOME at the Shortwave Listener (SWL) "Antenna Ashram"
http://groups.yahoo.com/group/Shortw...na/message/502
Some Say: On A Clear Day You Can See Forever.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
[ With the an AM/MW - FM - SWL Antenna of your own making. ]
..
..

  #9   Report Post  
Old January 5th 05, 04:06 PM
Mark S. Holden
 
Posts: n/a
Default

" wrote:

Hi--

I have a Realistic DX-160 in very nice conditiion I bought about 10
years ago (for $15!). My current living situation in Los Angeles no
longer affords me the luxury of an outdoor antenna, so I am using 40
ft. of 16 gauge copper speaker wire running along the ceiling moulding
as my antenna.

(ALSO: the DX-160 is in the same room with a lot of other electronic
equipment: computer, TV, stereo, audio recording equipment, mixer,
etc.)

I've read a lot in this newsgroup about modifying the DX-160, but as my
radio engineering skills are in their infancy, I've decided on
improving my antenna situation. It seems preselectors or the 9:1
matching transformer have favorable reviews here but I'd lke to know:

1) The DX-160 has an Antenna trim knob, so is a preselctor redundant?
2) The 9:1 matching impedance transformer is intriguing, but can they
be found/purchased already built?

Thanks in advance for any input!

SWS


If it were me, I'd sell the DX-160 and use the money I got for it, along with the money I was planning to spend on a preselector or mlb to buy a better radio.

I suspect a $75 Kaito or Degen 1103 would be easier to tune, more stable, and at least as sensitive as your DX-160.

For about $150 you could get a Sony 7600GR - it's one of the better portables, and has a good sync detector.

If you're willing to spend a little more, you'll have other options.

The thing is even if you added $1,000 of accessories to your DX-160, the heart of your system is still going to be a "nothing special" radio.

Making your own MLB really is easy, but with a 300 ohm antenna input, you'd want something in the range of 1.5:1 for a random wire.

I normally prefer MLB's to preselectors because I'd just as soon have fewer things to tweak, but on the DX-160, a preselector might do more for you than a MLB.

But a decent modern portable with a simple loop around the ceiling will probably give you the most bang for the buck.
  #10   Report Post  
Old January 5th 05, 05:12 PM
bpnjensen
 
Posts: n/a
Default

Correct, the DX-160 does not have an SO-239 (50-ohm) connector; it is a
high-z (500-600 ohm) connection already, and thus accepts a random wire
automatically "matched." If you had an antenna that terminated in
coax, you'd have to use a 9:1 matching tranformer "in reverse" to match
the impedance.

However, a 1:1 balun using ladder line or something similar might be
just the ticket...but the preselector idea sounds good too.
Bruce Jensen



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