Beware ICOM 746 owners! Do not use on 60 meters.
 

I'm passing this info along because I thought it was important for the group
(and before someone damages the radio they worked so hard for). The below
email was a response from an ICOM tech after an amateur op inquired about
the performance of the 746 and 746 Pro on 60 meters. Take the info for what
its worth.

73 de Paul

Good Morning....

Thanks for your e-mail.

The 746 final PA band pass filters were never designed to support operation
outside of the amateur radio bands. They will "stretch" to accept normal
operation in the MARS and CAP frequencies just above and just below the
amateur radio spectrum, but they will not support operation down in the 5
MHz area. They will heat up and you will damage the radio. About the only
two radios will have reasonable operation on the 5 MHz area are the 706MkIIG
and the 718.

Best Regards;

Mike Hilton

Technical Support Representative

ICOM America, Inc.

2380 116th Ave. NE

Bellevue, WA 98004

Ph. (425) 454-7619

Fax (425) 637-8417

www.icomamerica.com

Hmmm, mine works OK! I have made numerous QSOs on 60m
but most were during the first week that it was opened!

Nothing melted in mine.

On Sat, 22 Nov 2003 08:37:02 -0500, "Paul Vanasse"
wrote:

I'm passing this info along because I thought it was important for the group
(and before someone damages the radio they worked so hard for). The below
email was a response from an ICOM tech after an amateur op inquired about
the performance of the 746 and 746 Pro on 60 meters. Take the info for what
its worth.

73 de Paul

Good Morning....

Thanks for your e-mail.

The 746 final PA band pass filters were never designed to support operation
outside of the amateur radio bands. They will "stretch" to accept normal
operation in the MARS and CAP frequencies just above and just below the
amateur radio spectrum, but they will not support operation down in the 5
MHz area. They will heat up and you will damage the radio. About the only
two radios will have reasonable operation on the 5 MHz area are the 706MkIIG
and the 718.

Best Regards;

Mike Hilton

Technical Support Representative

ICOM America, Inc.

2380 116th Ave. NE

Bellevue, WA 98004

Ph. (425) 454-7619

Fax (425) 637-8417

www.icomamerica.com

Hmmm, mine works OK! I have made numerous QSOs on 60m
but most were during the first week that it was opened!

Nothing melted in mine.


YET! I think the prudent thing to do is make sure you are running
relatively low power when operating on 60M. You are supposed to be
running maximum of 50W ERP. I'd think 10 or 20 watts out of the
transmitter would prevent over-heating of the band pass filter components.



Ed WB6SAT

On Tue, 25 Nov 2003 23:12:36 GMT, "Ed G."
wrote:


Hmmm, mine works OK! I have made numerous QSOs on 60m
but most were during the first week that it was opened!

Nothing melted in mine.


YET! I think the prudent thing to do is make sure you are running
relatively low power when operating on 60M. You are supposed to be
running maximum of 50W ERP. I'd think 10 or 20 watts out of the
transmitter would prevent over-heating of the band pass filter components.



Ed WB6SAT
Yeah - that makes sense. Thank you.

If I go on 60 m again I will do just that.

The problem is to get the 10-20w out of the radio you may have to shove 100w
into the filter, and that's what hurts. You need to monitor the current
drawn to determine if there is a possibility of damage.

--
Clif Holland, KA5IPF
AVVid
Authorized Kenwood and Icom Service Center
816 W Shady Grove Rd
Irving, TX 75060

www.avvid.com

1-800-214-5779
972-870-0630 (Local)
"Ed G." wrote in message
.. .

Hmmm, mine works OK! I have made numerous QSOs on 60m
but most were during the first week that it was opened!

Nothing melted in mine.


YET! I think the prudent thing to do is make sure you are running
relatively low power when operating on 60M. You are supposed to be
running maximum of 50W ERP. I'd think 10 or 20 watts out of the
transmitter would prevent over-heating of the band pass filter components.



Ed WB6SAT

"Clif Holland" wrote in message
...
The problem is to get the 10-20w out of the radio you may have to shove
100w
into the filter, and that's what hurts. You need to monitor the current
drawn to determine if there is a possibility of damage.

Give this man a cigar because he's today's exclusive winner on 21!

The problem is that most modern hams today don't have a clue about what
you're talking about because most modern hams don't understand the theory
behind bandpass filtration, especially in their own Riceboxes. They actually
believe the radios will go from DC to Daylight once opened.

I believe this is the reason why Yaesu, Kenwood, and Icom haven't publicly
released the mods to these radios (other than to MARS/CAP members) because
these companies know damn well that they'll be performing a slue of warranty
repairs on the lot because some jack ass will actually try to use his radio
on the commercial AM broadcast band.

"Paul Vanasse" wrote in
news:VUlxb.6898$LV1.6847@okepread05:


"Clif Holland" wrote in message
...
The problem is to get the 10-20w out of the radio you may have to
shove
100w
into the filter, and that's what hurts. You need to monitor the
current drawn to determine if there is a possibility of damage.
Though I can't speak for the 746Pro I can firmly state that the BP filter
for the 746 DOES cover the 60 meter segment. It is spec'd for 4.0 to 8.0
MHz. Measurements in the lab showed no difference between the current
draw vs output power between 40 and 60 Meters. Assuming your antenna
presents a good match, you should be confident that the 746 will perform
just fine and within specs when modified for 60 meter operation.

73
Dave

Give this man a cigar because he's today's exclusive winner on 21!

The problem is that most modern hams today don't have a clue about
what you're talking about because most modern hams don't understand
the theory behind bandpass filtration, especially in their own
Riceboxes. They actually believe the radios will go from DC to
Daylight once opened.

I believe this is the reason why Yaesu, Kenwood, and Icom haven't
publicly released the mods to these radios (other than to MARS/CAP
members) because these companies know damn well that they'll be
performing a slue of warranty repairs on the lot because some jack ass
will actually try to use his radio on the commercial AM broadcast
band.

The problem is to get the 10-20w out of the radio you may have to
shove 100w into the filter, and that's what hurts. You need to
monitor the current drawn to determine if there is a possibility of
damage.


If you are having the above problem, then there's something wrong with
you radio. My 746Pro puts out nearly full power on 60M, as it does on
all other bands with absolutely NO change in current draw. If the default
40M filter was attenuating the 60M signal that much it would sure show up
on the watt meter!


Ed WB6SAT

Anyone that understands the operation of solid state PA sections with band
pass filtering for each band would not risk using the rig out of band. It
may not of hurt anything yet but why risk it. In time it will catch up to
you. The filters are designed to present a safe matched impedeance to the PA
for a specific frequency range and attentuate any spurs. Icom says no...what
about "dont do it " dont you understand?

Gary

On Sun, 07 Dec 2003 17:06:15 GMT, "Gary Poland" wrote:

Anyone that understands the operation of solid state PA sections with band
pass filtering for each band would not risk using the rig out of band. It
may not of hurt anything yet but why risk it. In time it will catch up to
you. The filters are designed to present a safe matched impedeance to the PA
for a specific frequency range and attentuate any spurs. Icom says no...what
about "dont do it " dont you understand?

Gary

Probably the same part that hundreds of others of us
"don't understand", who are enjoying our IC746 rigs
every day on 60m ya numbskull!