I've wanted to put an active shortwave antenna on my car for ages, but
didn't want to start messing with building one.

Years back I got replies from Universal, Gilfer, EEB etc. saying that
they never saw such a thing - but they might carry one if available.
In particular, several resellers said they might have liked a well
made, overload-resistant, mag-mount unit with a DC-RF splitter.

I might add I would have loved something that
- dampened both FM and Medium Wave (never seen one, not even plans for
one, and both bands are a big problem in my area)
- worked well on 12 Vdc (not 24)
- cost less than $1000.

I even talked to an active car radio antenna maker who told me the
design changes were trivial. Their best active car antennas had
separate AM and FM channels, so they could have moved the AM passband
up (they had standard cutoffs at 100 kHz and 5MHz, as to cover
longwave too) and left the FM channel unbuilt. The problem was, they
were an OEM, never did a production run of less than say 10k pieces
and weren't enthused about selling into a specialty channel with
ridiculous volumes and 100s of distributors in 3 continents!

As it happens, if you want something MIL-spec running on 24Vdc, have
$1000 to burn and you don't mind having to drill holes in your car,
and to cope with big signal above and below HF, you're well served.

I did some searching recently and still came up empry handed.

Is there something I have missed?

Ummm... The Michael Jackson 'aww-topsy'?
'Doc

On 9 Jan 2004 14:07:29 -0800, (SpamLover) wrote:

I've wanted to put an active shortwave antenna on my car for ages, but
didn't want to start messing with building one.

Years back I got replies from Universal, Gilfer, EEB etc. saying that
they never saw such a thing - but they might carry one if available.
In particular, several resellers said they might have liked a well
made, overload-resistant, mag-mount unit with a DC-RF splitter.

I might add I would have loved something that
- dampened both FM and Medium Wave (never seen one, not even plans for
one, and both bands are a big problem in my area)
- worked well on 12 Vdc (not 24)
- cost less than $1000.

I even talked to an active car radio antenna maker who told me the
design changes were trivial. Their best active car antennas had
separate AM and FM channels, so they could have moved the AM passband
up (they had standard cutoffs at 100 kHz and 5MHz, as to cover
longwave too) and left the FM channel unbuilt. The problem was, they
were an OEM, never did a production run of less than say 10k pieces
and weren't enthused about selling into a specialty channel with
ridiculous volumes and 100s of distributors in 3 continents!

As it happens, if you want something MIL-spec running on 24Vdc, have
$1000 to burn and you don't mind having to drill holes in your car,
and to cope with big signal above and below HF, you're well served.

I did some searching recently and still came up empry handed.

Is there something I have missed?
Sort of missed, though not for HF the Hyundai Santa Fe (small SUV type
vehicle) has no external antenna's. A friend has one and was told by
the dealer that it uses internal active antenna's - he confirmed with
the owner's manual. There are separate antenna's for MW and FM which
are located in two different locations. He hasn't let me strip down
the interior to check them out though 8-}

Radiomaster A-50?
McKay Dymek DA-100E?
MFJ-1024?
Sony AN-1?

--
Crazy George
Remove N O and S P A M imbedded in return address
"Howard" wrote in message
...

On 9 Jan 2004 14:07:29 -0800, (SpamLover) wrote:

I've wanted to put an active shortwave antenna on my car for ages, but
didn't want to start messing with building one.

Years back I got replies from Universal, Gilfer, EEB etc. saying that
they never saw such a thing - but they might carry one if available.
In particular, several resellers said they might have liked a well
made, overload-resistant, mag-mount unit with a DC-RF splitter.

I might add I would have loved something that
- dampened both FM and Medium Wave (never seen one, not even plans for
one, and both bands are a big problem in my area)
- worked well on 12 Vdc (not 24)
- cost less than $1000.

I even talked to an active car radio antenna maker who told me the
design changes were trivial. Their best active car antennas had
separate AM and FM channels, so they could have moved the AM passband
up (they had standard cutoffs at 100 kHz and 5MHz, as to cover
longwave too) and left the FM channel unbuilt. The problem was, they
were an OEM, never did a production run of less than say 10k pieces
and weren't enthused about selling into a specialty channel with
ridiculous volumes and 100s of distributors in 3 continents!

As it happens, if you want something MIL-spec running on 24Vdc, have
$1000 to burn and you don't mind having to drill holes in your car,
and to cope with big signal above and below HF, you're well served.

I did some searching recently and still came up empry handed.

Is there something I have missed?
Sort of missed, though not for HF the Hyundai Santa Fe (small SUV type
vehicle) has no external antenna's. A friend has one and was told by
the dealer that it uses internal active antenna's - he confirmed with
the owner's manual. There are separate antenna's for MW and FM which
are located in two different locations. He hasn't let me strip down
the interior to check them out though 8-}

Thank you all!

Hmm, let's see...


Radiomaster: new to me, price OK, but not mobile, no AM dampening.

MFJ-1024: I knew that one, rather similar, probably easier to
repackage or fit on a a magmount. Attenuator: very useful!

Sony AN-1: old model, discontinued; as above, but no attenuator (?)

Hyundai Santa Fe: ok, it's built into a car that's not my model, no
SW, no idea what it is. [My old Celica had a hidden AM/FM windshield
antenna already 15 yrs ago, and worked very well, but I stuck a whip
on the side of the sunroof for SW...]

MJ aww-topsy: autopsy? Uh?



Methinks the product I want is still firmly planted in the imaginary
domain!
If I get off my bony butt and build it, I'll share the joy.

Again, if anyone has suggestions for plans (both ELECTRICAL and
MECHANICAL!), here's my dream specs, which I bet would make several
people happy:

- Preamp passband optimized for 3-26 MHz, matching short telescopic
whip (remember, SW-BCL more than ham radio), rolling off steep on
either side. Not that easy, may require a bit of creativity. In my
area, a tight perimeter around the HF passband is essential. Sometime
my car radios don't receive ANYTHING AT ALL because of monstruous FM
overloads.

- Powered by 12Vdc, via thin 50 Ohm coax, RG 174 or similar. Pretty
standard too.

- Mag mounted, for easy installation even on rental cars, etc.
There's a ton of those out there for VHF / UHF / CB etc.

- Power / RF splitter, maybe with attenuator knob.

- Additional step-up RF transformer for matching coax to random-wire
socket on portables (I tried it, it does make a big difference).

Any hints, other than using a glorious J310?