[R-390] The Saga Pt 6 (Antenna Balun

[Judi Doran]

It seems that I read somewhere about  measuring the input Z of receivers and 
it was all over the place. guess I could put the antenna analyizer on the 
input and see what it says.    I strongly suspect that it also depends on 
how the rf was aligned/ balanced   Bernie
----- Original Message ----- 
From: "rbethman" <rbethman at comcast.net>
To: <r-390 at mailman.qth.net>
Sent: Tuesday, September 21, 2010 12:01 PM
Subject: Re: [R-390] The Saga Pt 6 (Antenna Balun


>  Bernie - I don't know what "improvement" will be seen.  It begins to
> get into what specific Signal Generator is used, how its impedance is
> effected, and other things.
>
> Roger R. will tell you that they spent their career(s) using
> AN/URM-25(X) sig gens.  By their nature, they were issued with a 50 ohm
> Z "phantom/dummy" antenna.
>
> Therefore you either use it into the "balanced" input - therefore
> tweaking and peaking for a 50 ohm match, or you used the "C" connector,
> and flipped the internal cables.
>
> The net result was a VERY sensitive receiver, but it really wasn't
> "peaked and tweaked" for the "balanced impedance" input.
>
> I've yet to locate or discover an AN/URM-25(X) with the adapter for the
> balanced input.  I use an AN/URM-25(D) and the TS-585D/U for the audio
> output readings.
>
> I'm extremely happy with the results!
>
> I even use the same lash-up for my Northern Radio SP-600.
>
> Shake them and bake them with what you have - AND - you can make work!
>
> Nothing wrong with Tisha's method!
>
> Bob - N0DGN
>
> On 9/21/2010 11:49 AM, Bernie Doran wrote:
>> what improvement is actually shown by the balun, vs the coax flipover or
>> grounding one pin of the balanced input?  Bernie W8RPW
>> ----- Original Message -----
>> From: "Tisha Hayes"<tisha.hayes at gmail.com>
>> To:<r-390 at mailman.qth.net>
>> Sent: Tuesday, September 21, 2010 9:55 AM
>> Subject: [R-390] The Saga Pt 6 (Antenna Balun
>>
>>
>>> "Has anybody tried a balun of the proper ratio to couple the coax to the
>>> balanced input?"
>>>
>>> Yes, I have, that is the way to go. I hand wound a 2.5:1 un-bal, put it 
>>> in
>>> a
>>> metal box with a coax connector on one end and a twinax pigtail on the
>>> other. It works just great.
>>>
>>> If I recall correctly, using the C connector there is a mini coax 
>>> flipover
>>> you need to do at the RF deck to get the best sensitivity.
>>>
>>>
>>> -- 
>>> Ms. Tisha Hayes/ AA4HA
>
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