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Old 07-10-2011, 02:53   #1
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SSB - Transmission Problems with Lower MHz

A little help: I have the Icom 802, with Auto tuner: I also have a large ground plate (18x6) and 3" foil running from the tuner to the plate - short run -possibly 1 foot. My reception is excellent on most freq.'s and I transmit very well on 8mhz and 12mhz and fair on higher freq.s. just can't seem to push out anything readable on 6mhz and forget 4mhz ... Going crazy - possibly someone can help... replaced wire from tuner to backstay and connectors as well.. Also: weird note: I am able to connect / trigger email (sailmail) on 6 mhz - but very rarely ever have voice comms..

any advise greatly appricated: I'm departing Gibralter soon to cross atalntic and of course all the nets are using 6mhz..

Thanks,
Jim
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Old 07-10-2011, 04:35   #2
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Re: SSB - transmission problems w/ lower mhz

Hi Bluemoon,

you did not tell us anything about the antenna.
Is it a backstay with isolators? How long is the total antenna until the auto tuner? (including the GTO15 or similar from the lower backstay to tuner)
Is it a vertical? How long?
Please inform us.

What you might try out on 6 Mhz (what is the exact frequency of your net?) is to cut one or 2 1/4 wave radials (about 12.5m long on 6 Mhz), lay them out on the deck and connected also to the auto tuners ground lug.
If this works, and the tuner is able to tune, you might fix them permanently e.g. along the toerail. Easy and cheap.

Jan
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Old 07-10-2011, 05:51   #3
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Re: SSB - transmission problems w/ lower mhz

Is the tuner successfully tuning on the lower freq's? Is the transmit power set to high? Have you checked the power output with wattmeter or are you just going on the fact that you can't communicate when you say you can't push out anything readable?

Eric
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Old 07-10-2011, 06:47   #4
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What time of day or night are you trying to use these lower frequencies, and over what distances? You will only get relatively short distances during daylight hours at 4 mHz, and maybe only somewhat better at 6 mHz.
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Old 07-10-2011, 10:51   #5
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Re: SSB - Transmission Problems with Lower MHz

+1 on all of the above.
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Old 08-10-2011, 02:33   #6
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Re: SSB - Transmission Problems with Lower MHz

First - Thank You for the reply's..
OK:
I am using the backstay with isolators which is on about a 15 degree rake.
Total ant. lenght: 39.7 feet (+/- 3") or 12.4 mtrs. -from the top insolator to the tuner.
detailsLength between isolators: 23.2 feet or 7.4 mtrs, I am using GTO15 wire: from backstay to the tuner: 16.5 feet or 5 mtrs.)
The freq: 6516 - but I seem to have the same issues anywhere along the 6mhz band..
I need to look up what a 1/4 wave radial is - sounds like a possible fix. 12.5 mtrs is long = boat only 11mtrs but really want it to work- sounds good Thank you

second ?:
Time of day trying to transmit: mostly early am, around 6 am to 10 am depending on net schedule... I have the exact same issues even in the middle of the night.
Transmit is set to : HIGH
The tuner will cycle (TUNE) and set itself..(??) Unit will not register any power bars / push as it does on other freq's.
I will need to check the output wattage.

Thanks again
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Old 08-10-2011, 07:09   #7
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Re: SSB - Transmission Problems with Lower MHz

When you press the TUNE button, the TUNE indicator should flash during tuning. If successful, the TUNE indicator will then stay on. If unsuccessful, the TUNE indicator will go off and the THRU indicator will come on. You should be seeing the power bar indicators while talking into the mic. If not, do you see the SWR indicator come on while talking?

Eric
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Old 08-10-2011, 08:22   #8
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Re: SSB - Transmission Problems with Lower MHz

Have you checked for a bad connection, especially on the ground leg of the system?
A tiny bit of corrosion is all it takes.

My long distance wifi system went deaf on me from that until I cleaned up a connector.

HF is no different.
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Old 08-10-2011, 08:35   #9
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Re: SSB - Transmission Problems with Lower MHz

What are people saying about your transmissions?? The 802 is notorious for clipping if it doesn't like antenna match, and we had a boat with exactly the same problem in the Pacific this summer. They were crystal clear on 14 mhz, but broke up badly on 4 and 6. This is a well known problem, and the fix is to send the radio back to Icom for modification. The newer radios are supposed to have been modified, but there are still a bunch out there with problems.
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Old 08-10-2011, 22:44   #10
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Re: SSB - Transmission Problems with Lower MHz

Jim,
With the limited info you've provided so far, the best we can do here is guess....
Eric and Don, etc. have started in the right direction...
But, perhaps I could piece a few things together, and attempt to come up with some possible solutions???
I'm assuming you are currently in Gibraltar???? (please advise...)

Congrats to you, for understanding that much of the HF maritime comms are on the lower HF freqs.....
You'll find quite a bit of cruiser's nets on 4, 6, and 8mhz...as well as most voice distress comms on 2, 4, and 8mhz....so getting your HF-SSB set-up working well on these freqs is important.....(as well as verifying your DSC operations, as this WILL be your primary means of contacting other vessels in your vicinity.....)



A) Up front, my first guess is that you have mulitple / a few minor problems.....
"M-802 clipping issue", incorrect transmit/rec freqs selected, on-board (and/or close-by) RFI, M-802 "speech comp" turned off, HF radio propagation vagarities, other boats/stations having their own issues, etc. etc...
(read further for the details...)






B) This appears to be okay....
Quote:
Originally Posted by bluemoon365 View Post
I have the Icom 802, with Auto tuner: I also have a large ground plate (18x6) and 3" foil running from the tuner to the plate - short run -possibly 1 foot.

Total ant. lenght: 39.7 feet (+/- 3") or 12.4 mtrs. -from the top insolator to the tuner.
detailsLength between isolators: 23.2 feet or 7.4 mtrs, I am using GTO15 wire: from backstay to the tuner: 16.5 feet or 5 mtrs.)
BUT, it does make me wonder where the tuner (AT-140 ???) is mounted, and how much GTO-15 wire is inside the boat and/or run near the M-802.....
As long as the AT-140 is mounted close to the backstay (typically 3' - 5' max) and AT-140 and GTO-15 wire are not too near the M-802, then your antenna system seems fine.....(if this is not the case, this could be one minor problem....but NOT in the top 3 items on my list...)
An approx. 40' long antenna, is approx. 1/4 wavelength on 6mhz, and this should be a decent antenna and provide an easy match for the AT-140....








Quote:
Originally Posted by bluemoon365 View Post
My reception is excellent on most freq.'s and I transmit very well on 8mhz and 12mhz and fair on higher freq.s. just can't seem to push out anything readable on 6mhz and forget 4mhz
Transmit is set to : HIGH
The tuner will cycle (TUNE) and set itself..(??) Unit will not register any power bars / push as it does on other freq's.Also: weird note: I am able to connect / trigger email (sailmail) on 6 mhz - but very rarely ever have voice comms..
C) You have not mentioned the serial number of your M-802???, nor its age????, nor how long you've had it installed????, nor whether it has always worked this way????
Nor, the actual power output of your M-802?????

(Having the answers to these question can help a lot, as will the answers to the following questions!!!!)

And while many do not have an external power meter, the M-802 DOES have its own rf output power meter (the 8 segment "S/RF" meter on the M-802's front display, with each segment corresponding to approx. 15 watts)...and you wrote:
"....Transmit is set to : HIGH The tuner will cycle (TUNE) and set itself..(??) Unit will not register any power bars / push as it does on other freq's...."
So, with "Hi Power" selected, and the tuner actually tuning (assume you meant that you do get a "TUNE" indication on the M-802 dsiplay, after pressing the "Tune" button, indicating that the AT-140 has completed its tuning and found a decent match)....
I'm wondering how much deflection of this meter when transmitting voice???
On various freqs bands???
How many segments show on "normal speech"???
Versus how may segments show on a whistle????
(and, just to make sure the transmitter is outputting fully, how many segments show when transmitting a carrier, such as when pressing the mic PTT button when in "FSK" mode????)

Knowing your M-802's serial number, and the answers to the above question, are VERY important pieces of the puzzle, as many of the early production M-802's (those with ser # below 0108261) had a significant transmit issue on voice (which did NOT affect data comms), known to many M-802 owners, and the marine electronics industry, as "the M-802 Clipping Problem"......
This is evident by abrupt voice cut-out, and/or significant reduction in power output when transmitting voice......AND the symptons DO vary somewhat from band-to-band and radio-to-radio....but are well know to may here on this side of the Atlantic....

Icom DOES have a FREE (and easy) fix for this issue....

See this discussion for details....
http://forum.ssca.org/phpBB3/viewtopic.php?f=5&t=12547

Again, using just the limited info we have, this is my "first guess" on what might be the cause of your M-802 troubles.....






D) My second place guess / possibe contributing factor, is channel/frequency you've selected for the "net"......the "freq" that you're attempting to communicate on, on 6mhz...
Quote:
Originally Posted by bluemoon365 View Post
The freq: 6516 - but I seem to have the same issues anywhere along the 6mhz band..

".....around 6 am to 10 am depending on net schedule..."

Also: weird note: I am able to connect / trigger email (sailmail) on 6 mhz - but very rarely ever have voice comms...
6516khz is the "ship's receive freq" / "coast station transmit freq" for ITU duplex channel 606, and although the reciprocal "ship's tranmit freq" of 6215khz IS the international (GMDSS) 6mhz voice distress, saftey, and calling frequency....the use of 6516lhz as a simplex freq for a maritime "net", although possible, seems odd to me...
And this fact, combined with the possibility that you've selected a "duplex channel" (606) 6516khz/6215khz to attempt "simplex" comms, makes me wonder if you've gotten the correct transmit and receive freqs selected????
Please verify this....

Some channel / freq tables....
EDIT: They didn't post well....sorry....


For all the Int'l HF Voice Maritime Duplex and Simplex channels, (and shared-use channels available in Region 2), see this page....
http://www.navcen.uscg.gov/doc/rtchan.txt







E) My third place guess is a combination of things....
Quote:
Originally Posted by bluemoon365 View Post
Time of day trying to transmit: mostly early am, around 6 am to 10 am depending on net schedule... I have the exact same issues even in the middle of the night.
Transmit is set to : HIGH
The tuner will cycle (TUNE) and set itself..(??) Unit will not register any power bars / push as it does on other freq's.
I will need to check the output wattage.
.....some of these things could be:
~~ Defective M-802, poor transmitter output on lower freqs (not too likely...)

~~ and/or significant atmospheric and/or local man-made noise on the lower freqs (always an issue with those new to HF)....
Getting a maritime HF set-up to communicate with other small vessels, when you are stuck in a marina and/or anchored-off a heavily industrialized area is difficult thing to do....(I know that while I was able to contact Herb in 2007, from Gib, on 12.359mhz, the RF noise on my end made it almost impossible.....so if you ARE in Gib, you're doing pretty good!!!)

~~ and/or your M-802's "speech comp" being turned off (the factory default), which can effect your average voice power output enough that if you don't have good propagation and low noise levels, you may have difficulty completing voice comms on some of the lower freqs.....

~~ and/or possible RFI getting into the M-802 (which CAN be very freq dependent) causing either erroronus SWR readings or RF output cut-backs or serious distortion of your voice signal.....(this is a fairly high probability, especially with other items attached to the M-802, such as your PACTOR modem, etc.....) Do you have adequate ferrites on all cables??? and have you attempted 4mhz and 6mhz voice comms with all other cables (PACTOR, etc.) removed from the M-802????

~~ and/or poor choice of freq / time for the communications path desired....although it seems that you understand this, be sure to attempt 4mhz comms to a "known" good station....(such as Monaco Radio, 3AC)
I hear Monaco Radio's hourly anouncements (and national antheym) here in Florida on a regular basis on 16mhz and 12mhz....so I do know they are on the air.....try them in the evening (or early mornings) on ITU ch. 403 and 804.....(you will also work them on 1224, and possibly on 1607, but with weaker signals, as you might still be in their skip-zone on 16mhz...assuming you are in Gibraltar....Monaco is about 700nm from Gib...)
{I haven't heard Olympia Radio (SVN, in Greece), nor Oostende Radio (OST, in Belgium) in a while, but you may wish to attempt comms with OST on ITU ch. 411 and 815 (or even 1207), as Belgium is about 1000nm from Gib....}
These would be "known" good stations and give you a decent test on the lower freqs....
(If you're a licensed ham, you may try the 75/80m and 40m ham bands, and speak to many hams all over Europe and the US....as good tests for your system on the lower freqs....)

~~ You may also want to try the Coastal MF stations around you.....
(1.6mhz - 3.0mhz).....as well as contact with other vessels on 2mhz freqs....(yeah they're noisy, but give them a try....)
Just to verify that your M-802/AT-140/Backstay is working fine on these freqs as well!!!!
I believe you can raise Tarfia on 1704khz/2129khz Voice.....and raise Lisboa Radio on 2087.5khz DSC and work them on 2182khz voice....(check a recent copy of Reed's....)

~~ If you are still in Gibraltar, contact Sheppard's.....they have a radio tech (or contract one as needed), which might be worth the few pounds spent, should some of the above advice/questions be confusing to you....





{ BTW, just so you know I regularly communicate on low hf freqs, 3.6mhz - 4mhz over long distances (5000 - 6000 miles) from my boat, using my M-802/AT-140/Backstay antenna/Dynaplate grounding plates....from USA to EU all the time....(and if I stay up late enough, from Florida to Aus and NZ... as well)
Just last month, while spending a few hours speaking with some friends, around the SE USA, I was interrupted by a ham in southern Argentina (~ 6000 miles from me), asking if I could move up a few khz, as they were starting their "net" there in a few mnutes, it was no-big-deal and we moved up a few khz......So, if your system is done right, and pick the times/freqs correctly, long-range, low-freq, HF comms from a sailboat on salt water is "sweet"!!! }





F) There are other possible problems/issues that could be causing these symptons.....but without further info/data (answering all the above questions, etc.), there's no use in rambling on and on, wasting your time....






FYI, this is probably something to NOT do right away.....
Quote:
Originally Posted by bluemoon365 View Post
I need to look up what a 1/4 wave radial is - sounds like a possible fix. 12.5 mtrs is long = boat only 11mtrs but really want it to work- sounds good Thank you
Not that there is anything wrong with using tuned radials as a counterpoise, but please do all of the above / answer all the above first, before you go and layout some radials....







I do hope this helps....

Good Luck and Fair Wind....


John
s/v Annie Laurie
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Old 09-10-2011, 07:38   #11
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Re: SSB - Transmission Problems with Lower MHz

Quote:
Originally Posted by ka4wja View Post
D) My second place guess / possibe contributing factor, is channel/frequency you've selected for the "net"......the "freq" that you're attempting to communicate on, on 6mhz... 6516khz is the "ship's receive freq" / "coast station transmit freq" for ITU duplex channel 606, and although the reciprocal "ship's tranmit freq" of 6215khz IS the international (GMDSS) 6mhz voice distress, saftey, and calling frequency....the use of 6516lhz as a simplex freq for a maritime "net", although possible, seems odd to me...
6516Khz is also in the radio's memory as simplex channel 6-5 as well as channel 95 (6D ship to ship) of the 160 user channel's. I had also initially thought he may be trying duplex channels, but since he isn't getting any transmit power bars on his display, I think it is another issue such as high swr or radio hardware problem. Another thought is that he may be programming these freq's in but failing to program in the transmit freq as well...i.e. his channel is set for receive only.

Eric
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Old 09-10-2011, 09:18   #12
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Re: SSB - Transmission Problems with Lower MHz

[Correcting my typo.....the MF DSC freq is 2187.5khz.....Sorry about that, my fingers were faster than my brain!!!]


Eric,
Yep, my oversight....not seeing 6D....

My first guess is still the "clipping problem"......

With my second guess now being RFI / erroronus SWR readings / power fold-back.....
Quote:
~~ and/or possible RFI getting into the M-802 (which CAN be very freq dependent) causing either erroronus SWR readings or RF output cut-backs or serious distortion of your voice signal.....(this is a fairly high probability, especially with other items attached to the M-802, such as your PACTOR modem, etc.....) Do you have adequate ferrites on all cables??? and have you attempted 4mhz and 6mhz voice comms with all other cables (PACTOR, etc.) removed from the M-802????
Third guesses as stated above, and now what you highlighted (improper freq / mode programming).....
Fourth guesses: a combination of any of the above....


As for M-802 hardware issue, I placed that further down the list, as he wrote that he IS able to make sailmail connections on 6mhz....(I'm assuming that is with OSY, in Belgium???....on 6330.5khz???)
If he'd simply select a 6mhz channel, and switch to "FSKmode" and key the mic.....and observe the M-802's transmit output dsplay....and let us know if he IS getting full output, then we'd be able to eliminate a transmit PA and/or output filter issue as the culprit.....

Hopefully we'll see what he finds....


73,
John
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Old 09-10-2011, 09:53   #13
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Re: SSB - Transmission Problems with Lower MHz

Does anyone know if the Icom M710 may have the same issue.I bought mine in 2009.I don't have serial # handy.
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Old 09-10-2011, 11:34   #14
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Re: SSB - Transmission Problems with Lower MHz

Quote:
Originally Posted by highseas View Post
Does anyone know if the Icom M710 may have the same issue.I bought mine in 2009.I don't have serial # handy.
If you mean the "clipping" problem, the M710 is clean in this regard. I've got the M710-RT (the remote-head version, purchased in 2001), and it continues to be a great radio.
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Old 09-10-2011, 11:45   #15
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Re: SSB - Transmission Problems with Lower MHz

Thanks Paul,I think it is of low output power possibly,if there is a problem.When I was running the Amigo net last winter in Mexico some stations said I was weak.A couple of people looked at it,did some stuff.Will do more tests when I get back to boat this winter.
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