[Hallicrafters] Dummy antenna for S40 alignment

[Bill Gerhold]

Exactly right, and that is why in all my station setups, I have used 450 ohm
balanced line and a tuner.  This is the only way I know, that my receiver is
seeing the impedance it wants to see and I am getting maximum signal
transfer.  How do I know this?  Because the transmitter is tuned to the same
frequency which is typically at or equal to 1:1 via the tuner.  Therefore, I
also have a low SWR for the receiver as well.

I tried this little experiment, I pulled my SX-111 off line and connected
the rear antenna connector to my MFJ-259B with a short piece of coax.  I
then fed the MFJ signal into the receiver right in the middle of the 40
meter band.  Using the front panel trimmer on the SX-111, I was able to get
a nice 1:1 SWR between the MFJ unit and the receiver.  Turning the main
tuning knob on the receiver from band edge to band edge, saw the SWR slowly
creep up to way over 10:1 at the band edges with attendant signal loss.

Hence, a good SWR is as important for your receiver as it is for your
transmitter.

K2WH

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Al Parker
Sent: Friday, December 10, 2004 8:52 PM
To: Craig Roberts; Edward B Richards; hallicrafters
Subject: Re: [Hallicrafters] Dummy antenna for S40 alignment

hi guys,
    The main thing you wanta do is set up the rcvr for what impedance you
plan to feed into it.  If the S-40 has no antenna trimmer, then you can't
do any adjusting other than your alignment, e.g. SP-600.  If it does
you've got some leeway. (don't stop hr)
    A resonant antenna is resonant on only a very narrow band of freqs.,
whether it has a balanced, open wire feedline, or what. So, elsewhere, the
impedance is gonna be off, sometimes way off.
    What you really wanta do is use an antenna tuner for your receiver if
you're "band cruising" no matter what antenna you use.  You've either
gotta tune the antenna system to the rcvr or the rcvr to the ant. sys.
    I've done it, and demonstrated it to others, with SP-600's.  Any wire
is gonna be a very high, or very low impedance in many places across the
SW bands.  You can hear something then, but if you use a tuner and adjust
it to feed the rcvr in the imp. range it expects, just like "we know" we
hafta do with a transmitter, you'll hr more.  tuner - that's how you get
the best transfer of energy, rcvg or xmtg.
    that's my story & I'm stickin to it.
73,
Al the grouch
W8UT

----- Original Message ----- 
From: "Craig Roberts" <crgrbrts at verizon.net>
To: "Edward B Richards" <zuu6k at juno.com>; "hallicrafters"
<hallicrafters at mailman.qth.net>
Sent: Friday, December 10, 2004 5:19 PM
Subject: Re: [Hallicrafters] Dummy antenna for S40 alignment

>
> I was actually toying with the idea of building an old style open feeder
> line doublet, per Army instructions, for my Hammarlund SP-600 (which has
> a 100 ohm input impedance) and seeing if it would make any discernable
> difference.  Does anyone feed their antique receiver with an antique
> resonant antenna?  If so, how's it work?
>
> 73,
>
> Craig
> W3CRR


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