[R-390] Baluns Caps and Ballasts

[Cecil Acuff]

You do the alignment through the Balun.  It does the 50 ohm to 120 ohm 
impedance matching if wound properly.

Sure the most ideal situation would be to have twinax all the way to the 
feed point on the dipole but that's not how most are equipped these days...

Unless you build it yourself you will have a 50 or 75 ohm unbalanced antenna 
system.  There is a bit to be gained by using the Balun but not as much as 
using a balanced antenna system.

Cecil..
----- Original Message ----- 
From: "rbethman" <rbethman at comcast.net>
To: "R-390 HF Receiver List" <r-390 at mailman.qth.net>
Sent: Wednesday, July 20, 2011 6:02 PM
Subject: Re: [R-390] Baluns Caps and Ballasts


ONLY *IF* you do an alignment with a 120 Ohm signal generator.

Do you see a 120 Ohm terminator/dummy antenna with the AN/URM-25 series?

Sure wasn't part of the parts included.  Darn sure isn't in the NAVSHIPS
Manual either.

NAVSHIPS 0967-187-5010.pdf (A 35MB file.).

Bob - N0DGN



On 7/20/2011 6:53 PM, Dennis Wade wrote:
> Isn't the whole point of the balun to convert the *unbalanced* 50 ohms
> to the *balanced* 125??
>
> Doesn't that solve the problem, assuming one feeds the antenna
> properly, that is if feeding a balanced antenna (dipole) with coax
> using some sort of choke or other type of balun to keep symmetry.
>
>                Dennis
>
> On Wed, Jul 20, 2011 at 1:16 PM, rbethman<rbethman at comcast.net>  wrote:
>> Tisha, I hope you get some decent numbers using this balun.
>>
>> However, it is still based upon either an SO-239 or BNC input.
>>
>> That puts us back to the initial point of a feed-line that is unbalanced.
>>
>> I have a strong belief that "Flowertime" Roger using AN/URM-25s, a
>> TS-505 D/U and a TS-585 has served very well.
>>
>> I just don't see adding an "extra" item into the antenna string is going
>> to make it work better.
>>
>> Bob - N0DGN
>>

-- 
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|               AM Amateur Radio Operator    NØDGN                 |
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