Bob,

So you are going to 'locate' your Random Wire Antenna in the Attic
and use a Magnetic Longwire 'type' Balun (MLB}.
- - - Here are My Thoughts:

#1. {First=Job #1} Make sure that you have a good outside Ground Rod
and a Heavy Duty Ground Wire routed/running up to your
radios/receivers.
+ TIP#1: Create a 'common' Ground Buss at this place in your "Shack"
to Tie-All Your [In House] Ground Together.

#2. Select your Long Wire Balun (actually a Matching Transformer) to
be used between the Random Wire Antenna Element and the Coax Cable.

#3. Select your Coax Cable (See the + TIP#2 below). Measure 'out'
distance (add an extra 5Ft to 10Ft) require for your Coax Cable. Fit
one-end of this Coax Cable with a Connector that 'matches-up-with'
your radio/receiver Coax Connector. Run/Route your Coax Cable to the
Attic. Then Fit the other-end of this Coax Cable with a Connector
that 'matches-up-with' your Balun's Coax Connector. If you follow the
+ TIP#2: Then also use the built-in Ground wire to Ground your Balun
in the Attic.
+ + + IMHO: For In-the-Attic Antennas this is the Best, Simplest,
Cost Effective and 'most' Practical Method of running/routing a
'common earth' Grounding Point to the Attic and ensuring that the
Balun is adequately Grounded.
= = = Sorry Everyone, but why create an overly reductant ground system
and bypass and duplicate the Grounding System that is being used for
the radios/receiver. [Ground to Radios to Attic Antenna is the
Shortest Route.] It is better for In-the-Attic Antennas; to first
improve upon the radios/receivers Grounding System: Then 'extend' it
up into the Attic to "Complete" the Entire Grounding System. {One For
All! -&- All For One!}
- - - Hey, What Works... WORKS !

#4. Select your Wire for your Antenna Element. I suggest using one
of these two high quality antenna wires: "Flex-Weave" Antenna Wire
-or- "QuietFlex" Antenna Wire.

Also look below for my additional comments marked with -RHF-.


iane ~ RHF
-o/m- http://groups.yahoo.com/group/SWL-AM-FM-Antenna/
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= = = "Robert11"
= = = wrote in message ...
Hello:

Will probably try a coax feed, and a Balun, to the random
length wire running around the four sides of my attic to
reduce noise, hopefully. Do listening only, up to 30 MHz.

a. For a receiving 9:1 Balun (coax to a random length wire
in attic), does the Balun have to be grounded ?

-RHF- YES - Either via direct Ground Wire and good Ground Rod.
- - - Or, indirectly via a Coax Cable that is itself Grounded.


Or, is it grounded "adequately" via the coax - to the radio
chassis - to an earth ground from the radio chassis ?

-RHF- YES - If you use the Larger Better Quality Coax Cable.
+TIP+ For "Receive ONLY" SWL Antennas:
- - - Buy the DSS Coax Cable that has a separate Ground Wire
'molded' along side the Coax Cable. Were ever your Coax goes
your separate dedicated Ground Wire goes.


[If the Balun Does require a ground (also), wouldn't this
possibly cause a ground loop in that it would be grounded
at both ends ?]

-RHF- Unless you are Transmitting do not concern yourself
with ground loops. However, do not mix your Household's
A/C Electrical Ground and your Antenna's Grounding System.


b. Anyone have any experience with, or opinions on:

-the 9:1 Balun by RF Systems in the Netherlands
(termed a magnetic balun, how it's different from a normal
toroidal transformer coupling, I have no idea ?)

-RHF- Here is a webpage with a write-up on the MLB
http://www.universal-radio.com/catalog/sw_ant/1465.html
http://www.hard-core-dx.com/nordicdx...d/magbal1.html


-or the unit by Win Radio (WiNRADiO WR-LWA-0130
Long Wire Antenna Adapter $39.95 ADP35)

-RHF- http://www.winradio.com/home/lwa.htm


c. Any significant difference in the type of coax used for
listening only, with a run of about 50 feet.

-RHF- Not Really


Used LMR 400 for my attic scanner, but would like to avoid the
hassle of stringing the large diameter coax again, and possibly
just use a small diameter coax. Would one likely notice any
difference up to 30 MHz ?

-RHF- Not Really

Thanks,
Bob

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