Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rating: Thread Rating: 3 votes, 3.67 average. Display Modes
Old 20-08-2011, 10:08   #16
Registered User

Join Date: Apr 2007
Posts: 718
Re: Ham on a Budget

Quote:
Originally Posted by sailvayu View Post
The icom tuner by the way CAN be used with any radio I have used one with a SEA 222 worked perfect.
You can with an external circuit for the control signals AND can adjust your power output to 10 watts cw during tuning. You can't do that with the 222 so I don't see how it could work with the icom tuner. At least not the AT-130/AT-140, not sure about the AH series. The AT-130/AT-140 tuners actually measure the power and will not go into tune mode if it exceeds around 15 watts as it will damage an attenuator circuit that is switched in during tuning.

Quote:
Oh and you must get the Boat license if you leave the country but you need that for a VHF as well.
A marine SSB installation requires a station license regardless if you leave the country.

Eric
__________________

__________________
fairbank56 is offline   Reply With Quote
Old 20-08-2011, 10:20   #17
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,872
Images: 4
Re: Ham on a Budget

Quote:
Originally Posted by John Drake View Post
A simple dipole that you can run up is a fine idea, but you will need quite a bit of GOOD quality coax to make that work.
With a reasonably well-tuned dipole, you can get away with merely average-quality coax and still do quite well. For example, if you have 50 ft of RG58 coax you're only going to lose about 1dB at 14 MHz.

Where the good (low-loss) coax becomes important is if the coax-fed dipole antenna SWR is very high and you are using a tuner to match this to your transceiver.

The coax between the tuner and the transceiver should always see a low SWR, so regular coax will work OK.

Of course, it's never a bad idea to use good coax. I'm just pointing out that you can get away with a lot as long as the antenna is well-tuned.

On my boat I carry a pre-cut 20-meter dipole and length of RG58 coax, all coiled up, as an emergency spare. Assuming I can find a way to put one end in the air (mast stump? whisker pole?) it's going to work pretty well as a sloping dipole and will not need a tuner.
__________________

__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 20-08-2011, 11:12   #18
Registered User
 
S/V Illusion's Avatar

Join Date: Oct 2007
Location: Lakewood Ranch, FLORIDA
Boat: Alden 50, Sarasota, Florida
Posts: 1,693
Re: Ham on a Budget

Quote:
Originally Posted by Paul Elliott View Post
With a reasonably well-tuned dipole, you can get away with merely average-quality coax and still do quite well. For example, if you have 50 ft of RG58 coax you're only going to lose about 1dB at 14 MHz.

Where the good (low-loss) coax becomes important is if the coax-fed dipole antenna SWR is very high and you are using a tuner to match this to your transceiver.

The coax between the tuner and the transceiver should always see a low SWR, so regular coax will work OK.

Of course, it's never a bad idea to use good coax.
I guess it depends on how important loss is. To illustrate, the 1dB loss to which you refer equates to over 20% loss of power at the antenna and more if there is a mismatch. If comms are marginal, that loss can make the difference between a mayday being/not being heard. Seems like a false economy to me.
__________________
S/V Illusion is offline   Reply With Quote
Old 20-08-2011, 11:46   #19
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,872
Images: 4
Re: Ham on a Budget

Quote:
Originally Posted by S/V Illusion View Post
I guess it depends on how important loss is. To illustrate, the 1dB loss to which you refer equates to over 20% loss of power at the antenna and more if there is a mismatch. If comms are marginal, that loss can make the difference between a mayday being/not being heard. Seems like a false economy to me.
Sure, compared to the mythical lossless cable! And I sort of pulled that 1dB number from my hat.

Looking at some styles of RG58 vs RG8 (RG8 is a typical "good" cable). I see that 50 ft of the RG58 gives you about 0.67db loss @ 14MHz, while the RG8 has a loss of about 0.33dB. Let's assume that our antenna SWR is 1.5:1 -- this gives us a total cable loss of (RG58) 0.75dB and (RG8) 0.36dB, a difference of 0.31dB.

0.31dB equates to a 7% power loss. I'm not going to feel too bad about 0.3dB in this case.

By all means, use the best cable you can afford, especially if it's going to hold up better against the salt air and sunlight. Make sure your connectors are well-installed. All these things can help, if only marginally, and it's a good idea. But if you want to try out a dipole antenna and you've got some RG58 on hand, I say go for it! I've even used RG174 for short runs of coax, at HF frequencies, but the loss is definitely significant (about 1.6dB in my example above.)
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 20-08-2011, 11:51   #20
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 1,793
Send a message via Skype™ to Auspicious
Re: Ham on a Budget

Quote:
Originally Posted by conachair View Post
What about winlink? http://www.winlink.org/userPositions

Seems popular and looks free.
Use of Winlink is free. You still need the hardware and software to connect. The SCS PTC-II modems are still the standard. Alternatively you can use WINMOR to connect to Winlink. WINMOR uses a soundcard to generate and decode the digital signals that are modulated and demodulated by a software TNC. Many if not most computer soundcards are not stable enough but you can buy a darn good external soundcard (like the SignaLink USB from Tigertronics) for about $100. WINMOR doesn't have the support that the SCS modems do so making a connection is more problematic. WINMOR is also not supported by the commercial services like Sailmail, ShipCom, and CruiseEmail. Winlink has committed to support for both WINMOR and Pactor (the SCS modems).

SCS recently released a new, yet higher speed modem. SCS PTC-IIpro and PTC-IIusb modems may well start showing up on EBay at reasonable prices as people upgrade, especially outside the US.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 20-08-2011, 12:31   #21
Registered User
 
S/V Illusion's Avatar

Join Date: Oct 2007
Location: Lakewood Ranch, FLORIDA
Boat: Alden 50, Sarasota, Florida
Posts: 1,693
Re: Ham on a Budget

Quote:
Originally Posted by Paul Elliott View Post
Sure, compared to the mythical lossless cable! And I sort of pulled that 1dB number from my hat.
Good pull! At 14MHz, that 1 dB loss is precisely the difference between RG58 and RG213 and is as high as 1.5dB loss compared with LMR coax. As no antenna provides a perfect match and no connector is loss-less, the loss is inevitably higher. Nothing mythical here!
__________________
S/V Illusion is offline   Reply With Quote
Old 20-08-2011, 12:49   #22
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Re: Ham on a Budget

What's mythical is why the argument :-)

1. The price difference between, e.g., RG58 and RG8X is negligible in the quantities we're talking about, so go for the better coax; and

2. I defy anyone...anywhere...to be able to discern a 1db difference on the receiving end.

BTW, for a vertical dipole on a sailboat, the thinner coax (RG8X) is preferable to, e.g., RG-213, RG-214, RG-8, LMR-400, etc. because it presents less windage and less weight, so it doesn't flop around so badly in a seaway.

But, fun on a quiet Saturday afternoon, huh?

73,

Bill
WA6CCA
__________________
btrayfors is offline   Reply With Quote
Old 20-08-2011, 14:02   #23
Registered User
 
drew23's Avatar

Join Date: Dec 2008
Location: cruising Mexico
Boat: Searunner 37 trimaran, Islander 34
Posts: 286
Re: Ham on a Budget

thanks all for such thoughtful replies!

yes, btw, I am a licensed ham - VA7DSX, hopefully soon to be VE0TF. I am jumping though as many bureaucratic hoops as are being thrown at me currently, and intend to have all of the appropriate station licenses to operate internationally.

much to think about! so far I'm gathering that spending the extra couple of hundred on an SGC tuner is not money wasted...?
__________________
"Analogies are dangerous, Amanda, because life is like a sandcastle."
blog: https://disengage.ca hf: VA7DSX / VE0TF instagram: mux23
drew23 is offline   Reply With Quote
Old 20-08-2011, 15:23   #24
Registered User
 
S/V Illusion's Avatar

Join Date: Oct 2007
Location: Lakewood Ranch, FLORIDA
Boat: Alden 50, Sarasota, Florida
Posts: 1,693
Re: Ham on a Budget

Quote:
Originally Posted by btrayfors View Post

2. I defy anyone...anywhere...to be able to discern a 1db difference on the receiving end.
No problem. Just to clarify - A one dB loss is not equivalent to a 1 dB in hearing it. The reference to dB is often confused between power, voltage and audio so it's important to differentiate when considering the topic.
As it applies to this discussion, a 1 dB loss in coax equates to a 25% loss of power at the antenna. For the typical 100w output transceiver, that's obviously a 25 w loss which can and usually is quite noticeable particularly when the signal strength is marginal.
The point being that the trivial cost difference between cheap and good quality coax is a false economy.
__________________
S/V Illusion is offline   Reply With Quote
Old 20-08-2011, 17:00   #25
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,005
Send a message via Yahoo to roverhi
Re: Ham on a Budget

The SGC 230 was the hands down winner as the best auto tuner available in the informal survey I did. I couldn't get the AH4 to tune with the 718 radio and needed to get my butt to sea. Turned out to be an open circuit in the radio not communicating with the tuner. Choice was to send the otherwise functioning radio back to Icom for repair and put off sailing for a couple of weeks or buy a tuner that didn't need input, other than the RF out, to tune. Since I'd already been delayed three weeks, went with everyone's reccomendation and bought an SGC 230. Installed it and left the next day. Perfect communications all the way to Hawaii with contacts from all around the Pacific Rim and across the US.
__________________
Peter O.
'Ae'a Pearson 35
roverhi is offline   Reply With Quote
Old 20-08-2011, 17:05   #26
Registered User

Join Date: Apr 2007
Posts: 718
Re: Ham on a Budget

Quote:
Originally Posted by S/V Illusion View Post
No problem. Just to clarify - A one dB loss is not equivalent to a 1 dB in hearing it. The reference to dB is often confused between power, voltage and audio so it's important to differentiate when considering the topic.
A db is a db. A 3db change in voltage is a 3db change in power.

Quote:
As it applies to this discussion, a 1 dB loss in coax equates to a 25% loss of power at the antenna. For the typical 100w output transceiver, that's obviously a 25 w loss which can and usually is quite noticeable particularly when the signal strength is marginal.
It's actually a 20.6% loss or 20.6 watts from the 100w output. It is not "quite noticeable", but actually barely noticeable under marginal conditions. It is a detectable change but not a significant one. When conditions are better than "marginal", it may take 3-6db for a noticeable change.

Eric
__________________
fairbank56 is offline   Reply With Quote
Old 20-08-2011, 17:07   #27
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Re: Ham on a Budget

Quote:
Originally Posted by fairbank56 View Post
A db is a db. A 3db change in voltage is a 3db change in power.



It's actually a 20.6% loss or 20.6 watts from the 100w output. It is not "quite noticeable", but actually barely noticeable under marginal conditions. It is a detectable change but not a significant one. When conditions are better than "marginal", it may take 3-6db for a noticeable change.

Eric
Yup!

If I turn the power output on my transmitter down from 100 watts to 79.4 watts (1db), ain't nobody, nowhere gonna be able to tell the difference!

But I certainly agree with Illusion about using good coax. Aside from the trivial price difference and the slight radiated power difference, there can be other good reasons. Like RFI suppression. Hence, my preference for double-shielded RG-214 or LMR-400 for long runs between the transceiver and the tuner.

Bill
__________________
btrayfors is offline   Reply With Quote
Old 20-08-2011, 17:54   #28
Registered User
 
Dsanduril's Avatar

Join Date: Aug 2011
Location: South Pacific
Boat: Outremer 50S
Posts: 1,451
Re: Ham on a Budget

Back to the OP's question - On our Cross we have a tuner installed in the aft end of the starboard float. As far back as we can get it. We then have a wire antenna that's approximately tuned for 20m that runs up through a bushing in the deck just above the tuner. We use a flag halyard to hoist the antenna up into the sky when we want to use it, then take it back down and coil it up on deck when we don't. Only time we have a problem is when reaching deeply on a port tack - the boom and the antenna can interfere with each other. Otherwise, that nice wide platform you have makes an ideal place for hanging an antenna only when you want it without having to put insulators in backstays, etc.

For a counterpoise (worthwhile IMO) we glued down some copper mesh in the bottom of the float under the antenna. Not a real pretty job, but no one ever goes there, it's dry, and the outside is usually in the water (except occasionally on a starboard tack with a good breeze). Of all the things I find most useful, a decent SWR meter. Allows you to make sure your tuner is doing its job, and to play around with other antennas if you want to.

I always have a 50' length of coax around (RG8 for the arguers here), and I put together dipoles all the time, but I like to play with those kinds of things. With a good dipole you don't need the tuner, and we do the same thing with the dipoles, hang them as inverted V's using the flag halyard and getting the width by tying one end to each float (or fore and aft if the direction is better). Never had a problem reaching pretty much the world using these inverted V's and an old Kenwood TS520 (nothing like a tube radio when your SWR is high)
__________________
Dsanduril is offline   Reply With Quote
Old 22-08-2011, 10:16   #29
Registered User

Join Date: Aug 2011
Location: Rockford WA
Posts: 5
Re: Ham on a Budget

The SGC websire has their tuner manuals in pdf format and discusses marine antennas. Another thought as to ground plane -- saw one boat use two lengths of 300 ohm ladder line one 17 ft and one 34 feet in the bilge. I would think direct burial electric wire would do same job - just seal far end to prevent moisture.

Be interesting to see EZNEC models of suggested antennas especially the one attached to a grounded back stay.

PhilE WA7JCE email phil at air-pipe dot com
__________________
PhilE is offline   Reply With Quote
Old 22-08-2011, 10:29   #30
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,363
Re: Ham on a Budget

I wonder if that electric fence wire that is braided into poly line would work well for a pull up/down antenna?
__________________

__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Reply

Tags
budget

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low Budget Extended Voyaging seamaster Powered Boats 8 21-08-2011 10:47



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:50.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.