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Search: Posts Made By: plebian99
Forum: Marine Electronics 24-01-2020, 14:53
Replies: 83
Views: 6,002
Posted By plebian99
Re: Backstay antenna length decision

Well we are not installing a marine HF antenna in a controlled science lab.

1. Picking a magic length or arguing about some minimum length is really a nonsense in the real world. Sure its a...
Forum: Marine Electronics 24-01-2020, 04:17
Replies: 83
Views: 6,002
Posted By plebian99
Re: Backstay antenna length decision

Any altternative to the normal backstay will need to be considered very carefully. Its unfortunate that many hams think that the only objective in antenna design is to get an antenna up regardless...
Forum: Marine Electronics 22-01-2020, 02:27
Replies: 83
Views: 6,002
Posted By plebian99
Re: Backstay antenna length decision

While any random length of wire works, if you are a long distance sailor you need to consider the efficiency of the overall antenna system.


If you are mainly a coastal cruiser and hugging...
Forum: Marine Electronics 03-01-2019, 23:48
Replies: 8
Views: 944
Posted By plebian99
Re: ssb n vhf switch

It can be done you need to use whats called a diplexer. You need a specific diplexer that is optimised for VHF and HF. I seem to recall that there was one such device in the Shakespeare catalog. ...
Forum: Marine Electronics 03-01-2019, 23:38
Replies: 9
Views: 1,572
Posted By plebian99
Re: SSB Antenna Question - GTO-15 Connector?

Search out of type HN Amphenol connectors. These are proper high voltage connectors. If you mount it on a insulated support and fill it with Dow Corning DC4 dielectric grease you will never arc...
Forum: Marine Electronics 03-01-2019, 23:27
Replies: 9
Views: 1,572
Posted By plebian99
Re: SSB Antenna Question - GTO-15 Connector?

I would not use a Millen connector under any circumstance. Its a poor connector design that is very dangerous. Worst of all is that the material that they use to make this HIGHVOLTAGE connector is...
Forum: Marine Electronics 28-02-2018, 05:40
Replies: 20
Views: 3,683
Posted By plebian99
Re: Icom M802 & AT-140 Grounding???

Is this a infomercial post?

What "S-units" did you use to make your anecdotal observations? Is your meter calibrated or are just reporting LCD bars or needle wiggles as gain?

Maybe you can...
Forum: Marine Electronics 24-02-2018, 19:38
Replies: 1
Views: 473
Posted By plebian99
Re: Crosstalk / interference between Autopilot and stereo

Its not really cross talk. Its just interference. All electronic equipment makes noise, and this noise can be radiated or conducted on the power cables or into other equipment. The other point also...
Forum: Marine Electronics 24-02-2018, 19:30
Replies: 8
Views: 2,417
Posted By plebian99
Re: MFJ-16010 HF long wire antenna tuner

Good point. Mount it at the feedpoint and see how long it lasts! Even buried in a lazarette or locker would be so inconvenient. Feeding coax to a backstay and then using this tuner would be an act...
Forum: Marine Electronics 24-02-2018, 19:14
Replies: 20
Views: 3,683
Posted By plebian99
Re: Icom M802 & AT-140 Grounding???

Its wishful thinking that you are going "un-bond" your DC and RF ground. A reality check with a multimeter will soon confirm this!

Un-bonding is actually not the thing to do in my experience. What...
Forum: Marine Electronics 24-02-2018, 03:40
Replies: 8
Views: 2,417
Posted By plebian99
Re: MFJ-16010 HF long wire antenna tuner

You seriously recommend people use this piece of crap on a boat?

Its a really a poorly designed and built Antenna Tuner whose ratings are very questionable. I have repaired a few of these for...
Forum: Marine Electronics 23-02-2018, 02:07
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

Try to get the coax feed plug that allows you to connect a coax fed antenna directly to the radio. I would try also to feed this piece of random wire with a RX only 9:1 Unun. You will pick up a lot...
Forum: Marine Electronics 23-02-2018, 02:00
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

You have have very clear thinking about RX antennas.

1. The angle is also important for receive. The height of the ionosphere varies hence the take off angle and the angle of arrival will vary.
...
Forum: Marine Electronics 22-02-2018, 13:11
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

That bit of wisdom might have some truth in it.

But what we are talking about is the very basics, like not putting a hole in your yacht hull and not go sailing. Radio physics might be hard to...
Forum: Marine Electronics 22-02-2018, 03:13
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

With due respect to your friend. On 13.5 mhz a 22 meter antenna will make a lousy antenna whose radiation angle is too high. I have attached a radiation angle plot of this antenna. The angle of...
Forum: Marine Electronics 21-02-2018, 03:37
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

Well if we deal with the facts its not hard to understand why less than perfect installations work over seawater.

Most installations that have problems have more to do with the way the antenna is...
Forum: Marine Electronics 20-02-2018, 04:04
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

All good points.

The point was not about trying to find a "magic length, it was trying to find a compromise antenna length with a reasonable radiation pattern from say 4 to 14mhz without...
Forum: Marine Electronics 20-02-2018, 03:46
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

No The Single radial is connected to your TUNERS grounding lug or bolt. You backstay or rigging wire is connected to the antenna terminal. Just think of it as an L or bent dipole. Its nothing more...
Forum: Marine Electronics 20-02-2018, 03:34
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

You want to open another "yacht ground " debate? Lets not go there. But if you want to put your "balloon" into a packet and called it a "Kiss magic Balloon" you will have sailors swearing that you...
Forum: Marine Electronics 19-02-2018, 13:03
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

A much simpler way if you using a random length of wire is simply to use a decoupled 9:1 UNUN. Reduces noise and is cheap. When a 9:1 UNUN is connected to a good backstay antenna on receive its a...
Forum: Marine Electronics 19-02-2018, 13:01
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

That point is not missed. Its the mistake made very often by many assuming that the RX only and TX antenna efficiency is 2 different subjects.

The junky pieces of wire that some yachts people use...
Forum: Marine Electronics 19-02-2018, 03:22
Replies: 58
Views: 5,501
Posted By plebian99
Re: Is length of antenna for MF/HF frequencies (Rx only) important?

I would not subscribe to the view that "longer" is better.

Most random wire antennas like backstays or sloping dipoles have a very good efficiency. There is little point in having the best ...
Forum: Marine Electronics 08-05-2017, 02:29
Replies: 48
Views: 14,354
Posted By plebian99
Re: Choice between Icom and Standard Horizon fixed mount VHF's

That is a fair point and no doubt Icom's marketing intent is to sell as many radios across all markets. In that sense they are mass produced.

There is however a big difference between a...
Forum: Marine Electronics 07-05-2017, 03:06
Replies: 48
Views: 14,354
Posted By plebian99
Re: Choice between Icom and Standard Horizon fixed mount VHF's

Most marine radios use the same internal electronics. They also have enough receiver performance. There is no need for super high performing ultra sensitive receivers since we only talking about line...
Forum: Marine Electronics 07-05-2017, 02:59
Replies: 16
Views: 2,740
Posted By plebian99
Re: BBC (and other) Shortwave Braodcasts, still on-the-air (and stong in Florida!)

Radio New Zealand and Radio Australia can be heard.

But there is a lack of variety on the shortwave bands these days for english listeners. The shortwave band seems to covered from one end to...
Showing results 1 to 25 of 73

 
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