[Antennas] AM Broadcast RX Antenna?

Tue Nov 17 20:12:48 EST 2015

Folks,
Why not check the MFJ catalog or DX Engineering and see what solution that 
they may offer ?
http://www.mfjenterprises.com/catalog.php

http://www.dxengineering.com/?gclid=CNCfuY_lmMkCFdgIgQodtVgLNA
73,
Barry
wb4izr

----- Original Message ----- 
From: "djed1--- via Antennas" <antennas at mailman.qth.net>
To: <kargo_cult at msn.com>; <antennas at mailman.qth.net>
Sent: Friday, November 13, 2015 10:03 PM
Subject: Re: [Antennas] AM Broadcast RX Antenna?

> As Hue has stated, the car radio may be designed for essentially an open 
> circuit (short antenna that looks like a small capacitor).  So a network 
> that matches to 50 ohms may not be the right thing.
>
> First, most receiving antennas at these frequencies are designed to 
> provide adequate signal without a 50 ohm match, so they don't need to be 
> tuned.  Even an 8 foot whip will probably have a tuned bandwidth of a 
> couple of KHz, so it's impractical for a consumer radio.
>
> Most importantly, you only need enough antenna receiving area (gain) to be 
> able to hear the atmospheric noise level, which will be very high at 660 
> KHz.  So the first thing to try is what you did- substituting the 8 foot 
> whip for the current antenna.  If your noise level drops when you 
> disconnect the antenna from the radio, then you're limited by external 
> noise and a bigger, or matched antenna won't improve your range.
>
> The next best improvement is to put a capacitive  "hat" on the 8 foot 
> whip, to make it effectively higher. This may be impractical.  After that, 
> try a series inductor or L network.  Since we don't know what the receiver 
> input is, this may not help (if the receiver is designed to work with a 
> short whip).
>
> Ed  W2EMN
>
>
>
>
>
>
>
> -----Original Message-----
> From: Hue Miller <kargo_cult at msn.com>
> To: antennas <antennas at mailman.qth.net>
> Sent: Fri, Nov 13, 2015 8:12 pm
> Subject: Re: [Antennas] AM Broadcast RX Antenna?
>
>
> 1000 miles out, year round, daytime too? That is a stretch.
> You already know,
> of course, that there's not much of a "match" possible
> to the car radio's
> AM
> antenna. The input to the car radio is for a low capacitance (short in
>
> terms of wavelength ) antenna.
> It's interesting i think that you got
> substantially better results with
> the CB type whip length.
> When i was
> working, i drove the hills on the Oregon coastal range. In DX
> season i could
> listen from
> Newport, Oregon, to CBC Vancouver 690, KIRO Seattle 710, KFBK in
>
> Sacramento ( i think ), and a
> all-comedy station on 1160 ( IIRC ) from
> Alberta. The 690 Vancouver
> would sometimes be fighting
> it out with XETRA on
> 690 from Mexico, and a few times Vancouver was
> nowhere to be heard and i
> had
> good copy on the Mexican. This is with a stock radio in a Ford
> Ranger
> truck.
> When i told the service order writer at the dealer that i wanted the AM
>
> radio noise situation in my
> Dodge Caravan taken care of, he told me i needed
> to go to an auto
> electrics specialty place and
> besides, no one uses AM any
> more, just a few old folks. The noise in my
> van, i think from the fuel
> pump,
> is so bad i cannot DX with it, just the local stations. The
> service people
> must hate working on
> the fuel pump because they all told me just to wait til it
> fails, not to
> be preemptive about it.
>
> One thing i've wondered about, is in
> the old Whitney car parts catalog
> was a "car antenna booster"
> which was
> simply some kind of coil that inserted at the base of the
> antenna. However
> just mentioning
> this makes me wonder how you'd install it. The claim was that
> it would
> pull in more & better. Seeing
> as the car radio expects only a
> certain capacitance hi-Z input, i don't
> see how a coil in the antenna
> would
> help. There's no magic to a coil. Maybe the benefit was
> 'psychological'.
> -Hue
> Miller
>
>
> ------ Original Message ------
> From: "KD7JYK DM09"
> <kd7jyk at earthlink.net>
> To: antennas at mailman.qth.net
> Sent: 11/13/2015 3:54:32
> PM
> Subject: Re: [Antennas] AM Broadcast RX Antenna?
>
>>The station my wife
> wants to hear is about 1,000 miles out.
>>
>>We did notice an improvement when
> holding the 102" whip against the
>>factory
>>antenna, greater signal strength
> and better signal to noise ratio, I
>>thought
>>we could do even better if it
> was matched to the primary frequency she
>>listens to during her morning and
> evening commute.  She doesn't listen
>>to
>>local FM at all, so it's either 660
> AM or the satellite radio.
>>
>>I have a close-body CB mount to modify to match
> the contour of the
>>truck bed
>>and some 1/4" aluminum to make a secondary
> mount about a foot above
>>that to
>>really stabilize things.  On the back
> side, inside the fender, I can
>>add a
>>matching network, then either T into
> the existing co-ax or remove the
>>factory antenna entirely and use just the
> 102" whip.  We're in a fringe
>>area
>>so the longer antenna would no doubt
> help with reception in general,
>>but the
>>primary concern is the DX AM
> station.
>>
>>Kurt
>>
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