Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 17-10-2016, 12:03   #1
Registered User

Join Date: Sep 2014
Location: Colorado
Boat: Pacific Seacraft Crealock 34
Posts: 37
Sharing Icom AT-140 With Two Radios

Greetings,

I have an Icom M802 connected to an AT-140 on my boat. I also have an Icom IC-706MKIIG that has been collecting dust for quite a while and would like to install it in the boat as a backup and to also do things that would require a real VFO (e.g. PSK31).

The AT-140 will work just fine with the 706 (already checked the specifications) and I'm thinking that all I need to do is build a switch box for the the tuner control connection and use an off the shelf coax switch for the antenna connection. Any concerns that I may be missing? Thanks for reading.
__________________

__________________
berferd is online now   Reply With Quote
Old 17-10-2016, 15:20   #2
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 1,886
Re: Sharing Icom AT-140 With Two Radios

berferd,
You seem to understand things well...and yes, this will work...
A bit of a complicated arrangement, but it will work...
{Personally, I'm not a fan of doing this to your primary HF radio (M-802) and possibly not having the radio on-line and working when needed in an emergency, etc., you've got two switches to throw (one a homebrew device), and the possible added issue of RFI......so, I'm not recommending that you do this....just answering your question...}


1) As for "concerns" you're going to need to switch 3 separate wires (+13.6vdc, Start, and Key) and keep the two radio's tuner control signals isolated from each other...
So, a multi-gang switch would be called for....or a multi-pole relay...

Also, understand that you will need to switch the "switch" or relay, with the radios powered off, so that whatever radio you wish to use will turn on and recognize that there is a tuner connected (if you turn the radio on and then switch, it will not know there is a tuner there....once the radio is "on" it doesn't "look" for the tuner until it is powered down and repowered up again...)


2) As for coax switching, "off-the-shelf" is a subjective term!!
I recommend the Daiwa CS-201....been using them for decades and they are reliable, work well, and have 70db isolation....(note that the "Alpha Delta" switches are also good for this)

But, please do not bother with cheap (MFJ, B&W, etc.) switches....not reliable and poor isolation...



3) BTW, since I don't operate PSK31, this may sound like an ignorant question....but, isn't there a way to "fine tune" stations in the software???
The M-802 tunes in 100hz steps, and I thought for sure that PSK software allowed you to tune using the computer / software / soundcard, once the radio's passband was centered on the particular slice (500hz to 3000hz, or so) of the band you desire??
Am I incorrect here??
Just curious...


Fair winds...

John
__________________

__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Old 17-10-2016, 15:49   #3
Registered User
 
S/V Illusion's Avatar

Join Date: Oct 2007
Location: Lakewood Ranch, FLORIDA
Boat: Alden 50 in Narragansett Bay, RI
Posts: 1,552
Re: Sharing Icom AT-140 With Two Radios

Quote:
Originally Posted by berferd View Post
Greetings,

I have an Icom M802 connected to an AT-140 on my boat. I also have an Icom IC-706MKIIG that has been collecting dust for quite a while and would like to install it in the boat as a backup and to also do things that would require a real VFO (e.g. PSK31).

The AT-140 will work just fine with the 706 (already checked the specifications) and I'm thinking that all I need to do is build a switch box for the the tuner control connection and use an off the shelf coax switch for the antenna connection. Any concerns that I may be missing? Thanks for reading.
Without over complicating this, yes, it will work fine. I base this on similar configuration on our boats for the past 20 years. By the way, either radio will recognize the tuner by simply pushing the 'tune' control.
__________________
S/V Illusion is offline   Reply With Quote
Old 17-10-2016, 15:53   #4
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 1,886
Re: Sharing Icom AT-140 With Two Radios

S/V Illusion,
I've never tried this...
Quote:
Originally Posted by S/V Illusion View Post
By the way, either radio will recognize the tuner by simply pushing the 'tune' control.
Thanks for the clarification....
I know the radio doesn't know it's there, and doesn't display any "tune" indication, so I assumed you have to have the tuner connected upon power up...appears I was wrong...

Thanks!

John
__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Old 17-10-2016, 16:34   #5
Registered User
 
El Pinguino's Avatar

Join Date: Aug 2013
Location: el campo
Boat: 39' Westerly Sealord
Posts: 3,179
Re: Sharing Icom AT-140 With Two Radios

Maybe this would work for you .... AMS-33

ELAD make good stuff..

EDIT.. and they have a US agent.
El Pinguino is offline   Reply With Quote
Old 17-10-2016, 16:47   #6
Registered User
 
sy_gilana's Avatar

Join Date: Jan 2005
Location: On board
Boat: Van de Stadt 50'
Posts: 1,042
Send a message via Skype™ to sy_gilana
Re: Sharing Icom AT-140 With Two Radios

Thats a bit complicated.

We have an antenna patch bay, the HF through the tuner, 2 vhfs and an FM all come to the patch bay, on the other side of it, all the radio antenna cables come to the patch bay.

I have 3 jumper cables that can cross connect any radio to any antenna.

The Tuner is supplied by a separate DC supply, with a power and "tuned" LED.

I also can disconnect my SSB Inverted L antenna outside of the boat before the tuner when there is lightning around.

Can post photo of the shack if you like.
__________________
Tight sheets to ya.
http://gilana.org
sy_gilana is online now   Reply With Quote
Old 17-10-2016, 18:02   #7
Registered User

Join Date: Sep 2014
Location: Colorado
Boat: Pacific Seacraft Crealock 34
Posts: 37
Re: Sharing Icom AT-140 With Two Radios

Thanks for all the replies and suggestions.

I thought having an A-B switch (4PDT) for the AT140 control lines would be pretty straightforward and keep the radio not in use completely isolated from the AT140. I would have to make sure that the box is shielded properly from RFI of course.

I see one person has a patch panel. There must be others who have more than one HF radio on board that use the backstay for an antenna.

Regarding the PSK31, IIRC, you need a radio than can tune in 10hz steps notwithstanding the capabilities of the PSK31 software. But I've been inactive for quite a while, so maybe my memory is a little fuzzy on this. Besides, even if I could do it on the M802, I am already using the accessory socket for the Pactor modem keying/modulation.
__________________
berferd is online now   Reply With Quote
Old 18-10-2016, 10:55   #8
Registered User

Join Date: May 2016
Posts: 35
Re: Sharing Icom AT-140 With Two Radios

There are many advantages to using the ham radio for ham operation. I dont own that one, but all competitive radios have neat stuff that might be out of place on a dedicated marine ssb. In addition, having a backup is usually a good idea.
The biggest concern is insertion loss. When purchasing the AB switch, that is the most important spec. A couple of high quality patch cables, and that is ALL you need, assuming you only have one antenna on your boat.
Just be careful to power the radio off that is to be switched away from the antenna.
__________________
Redpcx is offline   Reply With Quote
Old 18-10-2016, 12:47   #9
Registered User

Join Date: Sep 2014
Location: Colorado
Boat: Pacific Seacraft Crealock 34
Posts: 37
Re: Sharing Icom AT-140 With Two Radios

Thanks, would like to see that. Does your antenna tuner have control cables (like the ICOM) that have to be switched between radios?

Quote:
Originally Posted by sy_gilana View Post
Thats a bit complicated.

We have an antenna patch bay, the HF through the tuner, 2 vhfs and an FM all come to the patch bay, on the other side of it, all the radio antenna cables come to the patch bay.

I have 3 jumper cables that can cross connect any radio to any antenna.

The Tuner is supplied by a separate DC supply, with a power and "tuned" LED.

I also can disconnect my SSB Inverted L antenna outside of the boat before the tuner when there is lightning around.

Can post photo of the shack if you like.
__________________
berferd is online now   Reply With Quote
Old 18-10-2016, 13:04   #10
Registered User

Join Date: Sep 2014
Location: Colorado
Boat: Pacific Seacraft Crealock 34
Posts: 37
Re: Sharing Icom AT-140 With Two Radios

Thanks for the pointer, but that would be overkill for my needs (and would not handle switching the control lines anyway). I only have one HF antenna and two HF radios. An A/B coax switch (like the Daiwa CS-201 recommended by John) combined with a separate (shielded) switch for the control lines is the direction I am leaning towards but am open to other suggestions.

Quote:
Originally Posted by El Pinguino View Post
Maybe this would work for you .... AMS-33

ELAD make good stuff..

EDIT.. and they have a US agent.
__________________
berferd is online now   Reply With Quote
Old 18-10-2016, 13:24   #11
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 1,886
Re: Sharing Icom AT-140 With Two Radios

Red,
1) Actually the concern is not insertion loss....at HF, even a toggle switch from the hardware store won't cause much loss...
The issue is isolation...(although, if you use one of the switch brands I mentioned, it isn't a concern)
2) And, FYI, it matters not if the radio not in use is powered up or not...if the radio is connected to the switch, it is exposed to the transmit energy, the same whether powered or not...which is why the switch isolation is the important spec here...
(I sometimes leave one of my rigs at home powered up on the "not in use" side of the switch to monitor my transmit signal and do tests/evaluations...myself and others have been doing this for decades...)
Quote:
Originally Posted by Redpcx View Post
The biggest concern is insertion loss. When purchasing the AB switch, that is the most important spec. A couple of high quality patch cables, and that is ALL you need, assuming you only have one antenna on your boat.
Just be careful to power the radio off that is to be switched away from the antenna.
This subject comes up quite often on the ham radio discussion boards (usually every month)....so, here is what I wrote just a couple months ago...

Quote:
1) The short answer is:
If you have a switch with adequate isolation (which is what everyone is recommending), there is no possibility for damage.

Daiwa, Alpha Delta, etc. switches offer enough isolation to do this job just fine...(I myself use Daiwa and Bird switches)

Look for isolation specs of 50db to 60db, or higher...

(Daiwa CS-201 specs show 60db at 600mhz, and I find >70db or so at HF...a great switch!! My Bird 74 shows > 85db at HF!!)


https://www.dxengineering.com/parts/dwa-cs-201a

http://www.alphadeltacom.com/pdf/Delta%204%20Switches4.pdf

http://www.birdrf.com/Products/Components/Selector-Switches/74_6-Position-Coaxial-Selector-Switch.aspx


Other switches, with lower isolation (or unknown isolation specs), are usually not recommended, as they can allow too much of your transmit power thru the unused ports, and could be damaging to your other radios' receivers....
Some switches to immediately discount are the "unknown" switches, "CB radio switches", etc....heck, even the B&W multi-switches have fairly poor isolation, and I'd not recommend them.

Most receivers and sensitive RF gear are designed to handle signals as strong as +20dbm....and some receivers can handle +30dbm, that's one watt....while some sensitive test gear is spec'd as "not to exceed +15dbm"....
But, for our HF ham gear, a safe spec is +20dbm....(but, typically no damage would occur even at +30dbm...)

Makes NO difference if the rig is "on", "off", has power to it or not...if it is connected to the coax switch, it is exposed to the RF signal...
And, if you use headphones on the rig that you are not transmitting on, you can use it to monitor your own signal (I've been doing this for many decades!)




2) The long answer is:
Well, it's longer!

If you look at the entire issue in terms of "isolation" (or "path loss" ), and use db and dbm, etc., the whole subject becomes clear...
(I will "round off" the numbers to the nearest whole db)


100 watts = +50dbm
S-9 +60db (typically) = -10dbm
That's a 60db difference...


Free space path loss (direct-wave, line-of-sight):
1.0 miles distance @ 14.25mhz = 60db
1.25 miles distance @ 3.8mhz = 50db


Examples:
a) Two hams, living about 1 mile from each other....
Both have 3-ele triband yagis at 35' - 40' (typical antennas)
Neither has an amp...

If their antennas are pointed at each other...

100 watts (+50dbm) minus coax loss, plus antenna gain = +55dbm ERP (approx.)....
+ 55dbm, minus path loss (~ 60db @14.25mhz), plus other station's antenna gain and minus his coax losses = 0dbm (which is approx. S-9 +73), a whopping strong signal....but certainly not one that would "damage" your radio...
{yes, you might have trouble copying weak signals when your ham buddy a mile away from you is on-the-air, but that's a whole 'nother discussion!}
(they can co-exist on-the-air better, if they point their antenna nulls at each other....sometimes this can make a 20-30db difference each....and depending on where they point their antennas at any particular moment, they can find many signals from 1000's of miles away to be stronger!)



b) The same two hams....
This time on 75 meters, with dipoles in the trees out behind each others' houses....distance between antennas is about 1.25 miles....and let's just say that these antennas have 0dbi gain, including coax losses...(in the real world, line-of-sight, on the horizon, probably less than that....but for sake of this example, let's just say 0dbi...)

100 watts (+50dbm) minus coax loss, plus antenna gain = +50dbm ERP (approx.)....
+ 50dbm, minus path loss (~ 50db @3.8mhz), plus other station's antenna gain and minus his coax losses = 0dbm (which is approx. S-9 +73), a whopping strong signal....but certainly not one that would "damage" your radio...
{And, again, yes, you might have trouble copying weak signals when your ham buddy a mile away from you is on-the-air, on a nice quiet winter night.....but, again, that's a whole 'nother discussion!}

(this example on 75m was my own for years, but we typically used amps during the summer months to work our other friends thru the T-storm static crashes....before he moved 15 miles west of town, my best friend and I gave each other whopping strong signals on 75....we could copy the other without an antenna!)



c) You've got two rigs that you wish to switch between..
You buy a nice antenna switch with 50db of isolation...

100 watts (+50dbm) minus the switch isolation (50db) = 0dbm (which, again, is approx. S-9 +73).... a whopping strong signal....but certainly not one that would "damage" your radio...

{If you increase the isolation (by using a higher isolation switch) to 60db, you end up with -10dbm (approx. S-9 +63)....and if you used a switch with 70db of isolation, you'd have -20dbm (approx. S-9 +53)...}

And, by good luck, even the worst performing HF rigs will still not "overload" with signals of -10dbm / S-9 +60 or so....
BUT, you can use this other rig in receive mode to actually monitor your transmit signal (use headphones on the other rig to listen to your transmit signal).....you can hear yourself, while making adjustments, and/or switching in/out processor, changing mics, etc...
AND, you can check how wide / how broad your own signal is....(a GREAT way of seeing how your mic gain, ALC, Carrier Level, processor, etc. controls how much you splatter, key clicks, etc.)
{Yes, we'd all love to see our rigs on a spec analyzer with white noise in the mic input....and some of us have this gear to do it, but most hams don't....but if you have two rigs and a good antenna switch, you can do a pretty good job without 1000's of dollars of test gear!}



3) As for "accidently transmitting on the wrong rig" (the one that is not switched to the antenna)....

This is a red herring issue, for a few reasons...
a) You're not going to transmit if you haven't listened....
b) The "port-to-port" switch isolation is the same for both ports, so no worries damaging the receiver of the rig that IS connected to the antenna...
c) Every modern ham rig has "SWR protection", and will fold-back (or cut-off) the transmit power when the radio is transmitting into a high SWR (or infinite SWR), as would be the case if transmitted into an "open circuit" (no antenna) or a direct short....
(now, I cannot guarantee that every rig will survive an indefinite period of time transmitting into an infinite SWR....but it should take you but a few seconds to figure out that you need to switch the switch! Just don't "hot switch" it!!)



4) For those who will say that all the above is true, but things can fail....
Yes, things can fail....but never had a Daiwa or Bird switch fail yet, and been using them (along with DowKey) for decades...

But, fyi....my own brain and hands have failed....which is why when connecting things up, I always double-check before turning things on, and/or transmitting....(and I have on rare occasions, found I connected the wrong cable!)


Sorry that the long answer was so long....
But, I hope you can now see that if you know the "isolation" of the switch you can make your own choices, and use the other rig as your "monitor", allowing you to evaluate both rigs, their settings, etc., and how you operate them....

Hope this helps!

73,
John, KA4WJA

Fair winds...

John
__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Old 18-10-2016, 15:25   #12
Registered User
 
patprice's Avatar

Join Date: Apr 2010
Location: Tasmania
Boat: Swanson 36 in Australia Bavaria 42 in Med
Posts: 146
Re: Sharing Icom AT-140 With Two Radios

Can anyone sell me a Remote Head Kit for a IC-706 Mk2G ? OPC-581.

And maybe bracket `MB-63.

Apologies for hijacking the thread!
__________________
patprice is offline   Reply With Quote
Old 18-10-2016, 21:17   #13
Marine Service Provider
 
Scott Berg's Avatar

Join Date: Jul 2011
Location: Aboard
Boat: Seaton 60' Ketch
Posts: 741
Re: Sharing Icom AT-140 With Two Radios

I have three (3) HF radios and four (4) antennas. Here is how I handle this:

Three radios (Icom 756pII, Yaesu FT600, Yaesu FT100D) are on a 4x1 Alpha Delta antenna switch; the other position is held by an MFJ 259b Antenna Analyzer that lets me see the antenna/tuner...

The common goes from there to another 4x1 AD switch, this one for the antennas. The positions are: Inverted L (mizzen cap jumped to the triatic) using an SG230, a 20m vertical dipole, a 3 band Hustler (15,20,40) on the rail, and a dummy load.

This means I choose one radio, one antenna, and I'm good to go. Note that only the Inverted L needs an antenna tuner. The dipole is cut to 20m (or 15) and the Hustler stingers are adjusted to resonance. Pick a radio, pick an antenna, transmit.

This is much easier with an SG230 (no control cable needed) than an AT140 Icom.

(I also have an SGC 500 amp and a Palstar antenna that patches in to the above bypassing the SG230 (limited to 200w); that uses a large knife dpdt knife switch and a 5kw 4:1 UnUn... radio is so much fun!)

73
__________________
Scott Berg
WA0LSS
SV CHARDONNAY
Scott Berg is offline   Reply With Quote
Old 19-10-2016, 11:41   #14
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 1,886
Re: Sharing Icom AT-140 With Two Radios

Pat,
Good news!!
A quick search found exactly what you want....but it is VERY pricey!!!
(and I think way over-priced)
Icom IC 706's 703's Separation Kit | eBay
That's the whole IC-706Mk2G separation kit, with OPC-581, MB-63, and MB-62....
For $185 USD!!!!


I don't think I'd pay that much (or about that), for the whole radio....so, I doubt that ebay listing is what will make you happy??

So...

Not sure about you all downunder, but up here our best bet for finding one of these would be:
a) local hamfests...
b) eham.net qrz.com qth.com classifieds...
c) and last stop would be ebay...
Quote:
Originally Posted by patprice View Post
Can anyone sell me a Remote Head Kit for a IC-706 Mk2G ? OPC-581.

And maybe bracket `MB-63.

Apologies for hijacking the thread!
Hope this helps??

Fair winds..

John
__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Old 19-10-2016, 11:48   #15
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 1,886
Re: Sharing Icom AT-140 With Two Radios

As far as hijacking the thread....got a quick question for Scott...

Scott,
A few years back I used a friend's 756ProII at his house for a weekend, and liked it....(a lot of the same DSP architecture inside the M-802), but didn't have another rig to A/B compare against...
So, I'm curious...

When you compare the 756ProII, with the FT600 and FT100D, what do you think??
Functions?? Functionality??
Transmit audio reports??
Receive??
Quote:
Originally Posted by Scott Berg View Post
Three radios (Icom 756pII, Yaesu FT600, Yaesu FT100D) are on a 4x1 Alpha Delta antenna switch;
Fair winds...

John
__________________

__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Reply

Tags
icom, radio

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
For Sale: ICOM M802 SSB, ICOM AT-140 Tuner, Pactor PTCIIpro with III Paul L Classifieds Archive 1 25-07-2012 19:34
For Sale: ICOM SSB with AT 140 Tuner YachtCalypso Classifieds Archive 2 07-02-2011 05:37
For Sale: Icom 802 Marine SSB Radio with AT 140 Antenna Tuner loved cruising Classifieds Archive 3 13-01-2011 07:54
For Sale: ICOM M802 & AT-140 Tuner Randyonr3 Classifieds Archive 6 09-01-2011 23:46


Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:36.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.