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Old 02-08-2006, 11:31 PM   #1
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Default Which TNC(HF modem) to get

Ok i recently purchased a new icom M710 with a tuner. My next inqury is regarding the TNCs or HF modems.

I read quite a bit about ptc IIe from SCS and i guess it can be upgraded to ptc III with firmware and more memory(unless it laready has enough memory). They are usually around $800-$1200 or so.

My question is why is the other modem like the KAM-XL from kantronics so much cheaper? Like 300-400 for a new one. I guess is it because it doesn't do pactor II or III.

Also could anyone tell me what data rates are normally achievable. When they say 1200bps is that the speed of the RS232 connection to the laptop or the speed of the HF connection.

Thanks,

Petar
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Old 02-09-2006, 05:59 AM   #2
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The fastest speed possible today is provided only by Pactor 3, a proprietary technology of SCS. The older (and cheap) TNCs will not work on Pactor 3. And you WANT Pactor 3.

The data rate that is achievable is dependent on the HF propagation link. The software (Airmail) controls the data rate, adjusting it to the highest data rate possible based on the previously received data packets.

Terry

(Off today sailing to Thailand. Back on the Internet in 2 weeks)
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Old 02-09-2006, 08:28 PM   #3
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Petar, let me expand just a bit on Terry's post.

The only modern TNC manufacturer today is STS, a German company. Since they own the market, the price is high but the good news is that they make excellent hardware. Your choices with them are either a IIe or a IIpro, the fundamental difference between them being that the later makes 'hands off' operation of the radio possible. For those of us long-term cruising, this is a huge convenience. OTOH it is not a necessity. Both these TNCs will run at Pactor I, II and III speeds IF you pay the additional licensing fee for Pactor III.

There are other TNC's available but they are typically based on older technology and can only operate at Pactor I speeds. This essentially elminates the option of obtaining large weather forecast files (text and graphics). Another problem with Pactor I is that some Winlink stations no longer offer Pactor I service. With only so many 'good propagation' hours in a day and an expanding user base, these stations want all transactions to be relatively prompt so they can service the most people. I would definitely not recommend a Pactor I-only TNC for that reason. I don't know what Sailmail's system requires so, if only planning to use Sailmail, you might research this with them.

Jack
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Old 02-11-2006, 10:11 AM   #4
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Petar,

I concur with al the above posters.

However, I believe that all you will ever need is Pactor 1 for that absolute necessarry text E-mail or text weather forecast on the high seas. ( ie the Kam.)

It depends where you want to cruise, but if it is in the Caribbean, or Med, chances are that your longest passage will be about 5 days or less. Then you will sit in a marina somewhere for days with a very fast, internet speed, WiFi connection or cable connection., or Internet cafe'.

All pictures and weather images can be downloaded then at Internet speeds.

Most cruisers spend a huge part of their time cruising, in marinas or on the hook close by an internet cafe, or cell phone-to-internet connection.

A used Kam TNC goes for about $100 on E-bay. Make sure the one you buy, can do Pactor 1. (fimware 8 or so).
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Old 02-11-2006, 10:34 AM   #5
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As far as whether Pactor 1 is still being accepted by the Winlink2000 nodes (shore stations) - you be the judge.

All the stations without a "+", still accept Pactor 1 connections.

Sailmail also works on Pactor 1 from the Bahamas, at least. But possibly all over the world.

Click here: http://www.winlink.org/stations.htm
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Old 02-11-2006, 09:32 PM   #6
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That link is a nice way to 'answer' the Pactor 1 question.

A close look will show, as I mentioned above, that you probably won't want to be relying on a Pactor 1-only TNC if cruising the Med. (Unfortunately, both the Austrian & Bulgarian stations offer limited freqs and poor antennas, from what I can tell). OTOH if Caribbean bound or in coastal N American waters - and Pactor 1 will meet your needs - then you have many PMBO options.

Jack
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Old 02-16-2006, 03:19 AM   #7
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I think the gap between the non pactor I and pactorII/III is pretty big. But I do want to be isolated from marinas and will be making passages as well. So for that reason the II or III speeds are importnat. I just hope I find a used ptc 2. They make so much noise on ebay that its almost not worth bidding.

I wonder if the pice gap between pactor I and II/III will get smaller as the speeds increase. The question is will that happen in the next year? Probably not. Unless the STS gets some
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Old 02-16-2006, 04:27 AM   #8
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For the times when cruising offshore, is there any reason why satellite phones should not be a viable alternative to pactor? Iridium phones in Oz can now be purchased by Aussies, who operate a business which takes them out of the areas of coverage of mobile phones, for as little as AU$400 (US$300). Costs for making calls and sending or receiving data files are as low as AU$0.70c (US$50c) per minute from and to anywhere in the world. My knowledge of Pactor is very limited and I understand little about the speed and reliability of the system. But I do know Iridium does not rely on propogation for quality or effectiveness,it will operate as reliably as does a GPS and it is no longer wildly expensive.

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Old 02-16-2006, 08:08 PM   #9
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Auzzee:

On the surface, satcom looks like an inviting alternative...and it's always going to be easier to use and more available (almost 24/7). The problem with it serving as a replacement for Pactor HF is in how a crew wants to communicate on a boat, which is usually a LOT! Once email is put aboard, it becomes a tool as well as a means to socialize long-distance. As the volume of email goes up, so does the cost when using satcom service. Moreover, some uses - e.g. attaching wx graphics - is not feasible with satcom, or there are other limitations on what can be retrieved (e.g. with Skymate). That's why almost every time we're aboard a larger boat that's being cruised on a much bigger budget than WHOOSH, they use Pactor comms far more than their satcom system. As the owner of a gorgeous NZ-built 65' ketch told me in Horta, he would hate to spend what it would take to do even a portion of his nav and wx f'cast work using his satcom. The crew of a 68' power cruiser, who's been all over the Pacific & Med, told us they work hard to avoid using their satcom system due to its cost. It seems that even the well-off like to avoid spending a dollar when they can.

Another reason Pactor is preferred is that its operation has been nicely married with other software programs and so, e.g. downloading GRIBs and plotting them directly on one's Maxsea software is all but automatic - even operating the radio is automatic once it's turned on and the laptop keyed.

Integration and cost seem to be big drivers for Pactor use, even aboard some gold platers.

Jack
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Old 02-17-2006, 04:37 AM   #10
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Point taken Jack. I guess the next concern is when to buy; sooner or later Pactor 3 will be obselete and Pactor 5 will be cheap. But the list is getting shorter. Still need Lectrasan, 2 new sails, windvane self steering and a different view across the bow.

David.

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Old 02-21-2006, 09:02 AM   #11
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Since cost is always a factor... You may want to start studying for your Ham license now. Sailmail is $250 a year for their email service (for non Hams) and Winlink is free for Hams. The Ham license will pay for that Pactor-3 in 4 years (just in time to buy that pactor 5 upgrade).
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