[Antennas] AM Broadcast RX Antenna?

Tue Nov 17 21:06:39 EST 2015

I just checked out C Crane - they used to have a long range AM (MW) antenna
for trucks - it's not in their catalog anymore.

73
David N1EA

On Tue, Nov 17, 2015 at 8:12 PM, Barry E. Maguire <bmaguire at att.net> wrote:

> 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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