loran questions

OK. Thanks, Larry. That means all those nice LORAN receivers for sale on
Eprey without couplers basically aren't useable. Which is probably why the
go so cheap......
 >> Stay informed about: loran questions 

In article <rDknf.8151$Y72.5181@bignews1.bellsouth.net>, "RB" <rbig DeleteThis @bellsouth.nospam.net> wrote:
>Got a question on LORAN sets. I don't want to get into the desireability of
>GPS as the nav mode of choice today. I'm fiddling around with LORAN and
>trying to get going with it.
>
>1. What is/are LORAN operating frequencies?
>
>2. Marine LORANS are found with external couplers (pre-amps) which go at
>the base of the fiberglass/whip antenna. Can marine LORANs which are made
>for use with external couplers give reasonably good performance without the
>coupler? Or, is lack of the coupler a "killer"?
>
>2. Are there marine LORAN receivers which don't require external couplers
>(i.e., that hook direct to the antenna)?
>
>3. If you have a marine LORAN which does in fact need an external coupler
>to get enough signal through and you don't have the companion coupler unit,
>are any commonly available pre-amp boards for the LORAN frequencies
>available? If so, where find?
>
>

Man, I had to do a little searching. We used to track Loran to check long term timming
stability of atomic clocks. 100 kHz seems the right frequency. A loran signal
is probably best received using a loop antenna, but for receiving multiple direction
signals a whip is needed I'm sure.
All you need is a 100kHz amplifier, probably low passed and preferably
bandpassed matched to the antenna, and to the receiver input.

greg
 >> Stay informed about: loran questions 

On Mon, 12 Dec 2005 14:00:42 -0600, "RB" <rbig.DeleteThis@bellsouth.nospam.net>
wrote:

>Got a question on LORAN sets. I don't want to get into the desireability of
>GPS as the nav mode of choice today.

===========================================

So you realize that LORAN is functionally obsolete and that a $100
WAAS enabled GPS will give you far better accuracy, and with far less
succeptibility to interference sources such as thunderstorms, ignition
noise, alternator whine, etc.?

If you are a real traditionalist I have a RayJeff RDF unit in the
garage that I might sell as an antique. It was my first electronic
navigation unit, purchased new in 1971. Accuracy? Maybe plus or
minus one mile at ten miles off the coast. LORAN C improved accuracy
to about 100 yards, WAAS GPS to about 10 to 20 feet.
 >> Stay informed about: loran questions 

"Larry" <noone.DeleteThis@home.com> wrote in message .> Killer. The very-low frequency
LORAN antenna is electrically 2340' long
> (1/4 wavelength on 100 Khz). To achieve this in an 8' long whip it is
> VERY heavily loaded with a large inductance and that coupler. No, you
> can only get it working with the cou0ler or a 2,340' long whip, your
> choice.
>
> >
> > 2. Are there marine LORAN receivers which don't require external
> > couplers (i.e., that hook direct to the antenna)?
>
> The couplers on the marine antennas are built into the whip. They're
> still there.
>
> >
> > 3. If you have a marine LORAN which does in fact need an external
> > coupler to get enough signal through and you don't have the companion
> > coupler unit, are any commonly available pre-amp boards for the LORAN
> > frequencies available? If so, where find?
> >
>
> It's not a preamp problem. There's tons of signal from teh MEGAWATT
> LORAN-C pulse transmitters and their massive capacitor hat loaded 850'
> tall antenna towers. The problem is that 2340' 1/4 wave whip it takes to
> hook 'em up.
>
> You need the antenna system it came with.....

While there is certainly no question that the matching coupler and 8' whip
are pretty much standard, just for fun we experimented with some of the old
TI lorans, and found that the SSB antennas on many power and sail boats
worked fairly well, with one major "gotcha". Loran C, at 100 khz is very
easily messed up by electrical noises from almost anything on a boat. Having
the 8' whip antenna up and away (several feet at least) from the noise
makers and the boat's wiring, made major differences in noise pick-up. Water
damaged TI loran couplers were pretty common, and you could pull the guts
out and throw them away, and jumper the whip connector to the signal feed
wire inside the coupler. Performance not perfect by a long shot, but if you
shut down the main engine and everything else, you could get a fix. (the
hard way)
Old Chief Lynn
 >> Stay informed about: loran questions 

I have a few loran couplers laying around, some trimble, northstar, TI,
possibly a SI-Tex. I could give you one for the price of shipping if you
want. Don't know what model Loran your looking at, some couplers
interchangeable, some not.

Eric

"RB" <rbig.TakeThisOut@bellsouth.nospam.net> wrote in message
news:rDknf.8151$Y72.5181@bignews1.bellsouth.net...
> 3. If you have a marine LORAN which does in fact need an external coupler
> to get enough signal through and you don't have the companion coupler
> unit, are any commonly available pre-amp boards for the LORAN frequencies
> available? If so, where find?
>
 >> Stay informed about: loran questions 

What is in these "couplers" is it just a huge inductor to cancel out
the capacitive reactance?

I discovered this phenomenon the hard way when I replaced the shielded
cable on my car antenna with just some simple coax. Absolutely no AM
signal at the end. Then I figured out why the real cable is a coax
with a very tiny center conductor inside a hollow tube to minimize the
capacitance. If you used something similar to connect any antenna to
your loran it would probably work better.

Have fun.
 >> Stay informed about: loran questions 

These are "active" antenna's. Power is provided via the coax and there is
a PCB in there with a pre-amplifier circuit. Some units have notch filters
and/or bandpass filters in them.

Eric

<nospam.don.DeleteThis@gmail.com> wrote in message
news:1135303953.704458.276600@g43g2000cwa.googlegroups.com...
> What is in these "couplers" is it just a huge inductor to cancel out
> the capacitive reactance?
>
> I discovered this phenomenon the hard way when I replaced the shielded
> cable on my car antenna with just some simple coax. Absolutely no AM
> signal at the end. Then I figured out why the real cable is a coax
> with a very tiny center conductor inside a hollow tube to minimize the
> capacitance. If you used something similar to connect any antenna to
> your loran it would probably work better.
>
> Have fun.
>
 >> Stay informed about: loran questions 

"Eric Fairbank" <fairbank56.RemoveThis@yahoo.com> wrote in
news:KaGdnSbo3qIMmzHe4p2dnA@comcast.com:

> These are "active" antenna's. Power is provided via the coax and
> there is
> a PCB in there with a pre-amplifier circuit. Some units have notch
> filters and/or bandpass filters in them.
>
> Eric
>
>

Don't confuse them. They think you can plug just any old thing into any
old thing just because it has the same BNC connector and it will be on the
cheap.

If we go telling them different, technicians' families will starve and have
a bad Christmas...

Not long ago I found a formerly-good GPS front end plugged into a formerly-
good LORAN receiver, myself...

They're pretty close, right?....(c;
 >> Stay informed about: loran questions 

On Fri, 23 Dec 2005 09:15:42 -0500, "Eric Fairbank"
<fairbank56.RemoveThis@yahoo.com> wrote:

> These are "active" antenna's. Power is provided via the coax and there is
>a PCB in there with a pre-amplifier circuit. Some units have notch filters
>and/or bandpass filters in them.

=====================================

Absolutely right. If anyone really wants to hack around with this
stuff I have a couple of Northstar LORAN-C units sitting around
without antennas or couplers. They were first class units in their
day and have SO-239 coax connectors on the back.
 >> Stay informed about: loran questions 

Wayne.B <waynebatrecdotboats DeleteThis @hotmail.com> wrote in
news:p22pq19betu33o8pqfrfdfjdt55kk7g4an@4ax.com:

> Absolutely right. If anyone really wants to hack around with this
> stuff I have a couple of Northstar LORAN-C units sitting around
> without antennas or couplers. They were first class units in their
> day and have SO-239 coax connectors on the back.
>
>

I have someone Christmas gift, too. I have a perfectly good-working
Stephens Engineering SEA-106 HF synthesized SSB Marine transceiver with
microphone and NO CABLES OR COUPLER in first class condition I'll give to
the first person who shows up to pick it up. If you have a SEA-106, or
know someone who has one, this one hasn't a scratch. It was at the main
helm of a motoryacht, inside in the air conditioning, all those years.
It's owner said it had been removed when they restored the helm's
woodwork and made a new panel for new gear. Someone threw out all the
cables and coupler which was dumped in another box away from the
transceiver. Sorry.... He said it was working when uninstalled, but he
wanted a marine radio that would work with his new ham license more
easily.

The power plug is marked with + and - and "ON" terminals, which I assume
is a remote power switch to just jumper out. I have no book, no cables,
as it was handed to me after installing a new Icom M802 on the boat. I
never turn down free stuff, even if I have no clue....

Of course, it comes with a full money-back guarantee....(c;

Munge up your email address and post it in reply if you want it....PICKUP
ONLY in Charleston, SC.
 >> Stay informed about: loran questions 

On Fri, 23 Dec 2005 19:50:37 -0500, Larry <noone.RemoveThis@home.com> wrote:

>I have someone Christmas gift, too. I have a perfectly good-working
>Stephens Engineering SEA-106 HF synthesized SSB Marine transceiver

===========================

I will see that and raise you a Stephens SEA112 with coupler. With
the right incentives I might also throw in a Wood Freeman auto pilot
assembly (chain drive). It is a mechanical marvel and only weighs 50
pounds or so.
 >> Stay informed about: loran questions 

Wayne.B <waynebatrecdotboats DeleteThis @hotmail.com> wrote in
news:n08pq15q3k6jfm2dp3godl17uj9k5o8iqj@4ax.com:

> I will see that and raise you a Stephens SEA112 with coupler. With
> the right incentives I might also throw in a Wood Freeman auto pilot
> assembly (chain drive). It is a mechanical marvel and only weighs 50
> pounds or so.
>
>
>

You know if we keep this up we'll end up with S/V "Newsgroup", a nice old
Morgan OI 41 loaded with antique electronic gear, for next Christmas...(c;
 >> Stay informed about: loran questions 

Wayne.B <waynebatrecdotboats.DeleteThis@hotmail.com> wrote in
news:n08pq15q3k6jfm2dp3godl17uj9k5o8iqj@4ax.com:

> I will see that and raise you a Stephens SEA112 with coupler. With
> the right incentives I might also throw in a Wood Freeman auto pilot
> assembly (chain drive). It is a mechanical marvel and only weighs 50
> pounds or so.
>
>

God, if the Ebay hawkers see this giveaway going on they're gonna have a
HEART ATTACK for Christmas!....(c;
 >> Stay informed about: loran questions