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Author Topic: ICOM 740 ?  (Read 1639 times)
N6AJR
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Posts: 9921




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« Reply #15 on: October 25, 2008, 10:41:46 PM »

that sounds like a hunndred dollar radio.  if it is missing this and needs that tweeked, I would not invest any more than that.

for a starter radio and especially if you have HOA problems think about something you can use in the shack and in the car.  like an ft 857d , a IC706 mIIG or an alinco dx70 .

all 3 do 2m and 440, and 6m and all ha bands all modes. used in the 400 to 600 dollar range and new the ft 857 is about 700 bucks.

 a screwdriver antenna for the car and a tripod with radials to mount it on for the shack, and at least you can get on the air.  good luck, have fun
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OLDGEEZER
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Posts: 48




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« Reply #16 on: October 26, 2008, 03:11:59 AM »

Thanks for your input Tom;

I'll consider your comments.........

All the Best

Dave
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WB8VMW
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Posts: 29




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« Reply #17 on: March 19, 2009, 03:03:01 PM »

I just picked up a 740 at a show and it looked good on the out side and of course the seller said it was in tip top shape. Well when I got it home and hooked it up the receive was ok but when I tune in a station it's like there is a notch that it blanks out. As it tune a station comes in and gets strong then it nuls out then on the other side it comes in strong again. On transmit I get form 10 to 20 watts and thats it. Should I put a rope on it and use it for fishing or take it back to the one who sold it to me and put it where the sun don't shine.
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K7KBN
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Posts: 2825




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« Reply #18 on: March 19, 2009, 06:01:49 PM »

VMW - you describe the problem as a "notch".  

The IC-740 has a notch filter.  Is yours turned on?

73
Pat K7KBN
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73
Pat K7KBN
CWO4 USNR Ret.
N6AJR
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Posts: 9921




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« Reply #19 on: March 19, 2009, 06:16:57 PM »

just for comparison sake you can buy a new yaesu ft 857 D for under $700

it does 2meters, 440 mhz, 6 meters, and 160 through 10 meters, and it does all modes, ssb, cw, digital, psk31, am  and fm. all bands all modes for under 700 bucks new, throw in a 12 v supply and a fan dipole you bild your self, and you are there,  used they go for aboput 500 550 als is the alinco dx 70 and the icom 706M II G for around 450 to 500 used.  just an idea, also  go to a local club nmeeting and find some more info on available righs,  I had a 740 and also a 735 and a 720 and got rid of them as "clunky"  I kept the 746 pro. ( I have 10 or 12 hf rigs, and I like to play...)
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WB2WIK
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Posts: 20635




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« Reply #20 on: March 19, 2009, 06:31:13 PM »

Unfortunately I just caught up with this thread and didn't see it earlier.

As an owner of *two* IC-740s back in the early 80s (bought them both "new", one for HF and one to use with VHF transverters), it's a nice rig.  However it certainly has some weaknesses.

One thing I found that "fails" -- a lot -- is transistor "Q5," on the front end board.  It fails from excessive RF voltage coming in the antenna port, which is a very common problem in a multoperator contest station.  This transistor shunts the RF input stage when you transmit, but if it fails, it shorts out and then permanently reduces receiver sensitivity until it's replaced.

Besides a high powered multiop station, the same transistor (which is originally rated only 60V breakdown) can fail from lighting transients and other causes.

WB2WIK/6
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WB8VMW
Member

Posts: 29




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« Reply #21 on: March 20, 2009, 04:01:48 AM »

I did check the notch filter and it's off. I have read the manuel several times and there are a lot about this radio I don't understand and I'm not into contest or field days. I am and old brass pounder and love to rag chew. Being 72 my brain is not vary good at learning new things.
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WB8VMW
Member

Posts: 29




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« Reply #22 on: March 20, 2009, 04:17:10 AM »

The reason I bought this radio was because the price was right for me( little did I know). I have a HW 101 I built in the early 70's and a HW 16 but when the kids came along and I got two jobs my air time went out the window. Two years ago I retired and wanted to get back on the air but the 101 and 16 had been sitting to long and needed a lot of work. I guess my only choice is see how much to repair the 740 or 101 and do what ever it takes to get back on the air. 99.9 % of my on air time is pounding brass and I love to rag chew. thanks guys for the info.
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W9JAB
Member

Posts: 70




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« Reply #23 on: March 20, 2009, 09:17:23 AM »

I also have an Icom 720A, I do not know the difference between the 720 & the 720A, But mine seems to work just fine, the weak link is the stepper relay in the tuner. I ,m send a link for a mod. but I been told the repair out weights the worth of the radio.
http://www.hayseed.net/~jpk5lad/IC-720/720Index.htm


JOE
W9JAB
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VE3GNU
Member

Posts: 86




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« Reply #24 on: March 20, 2009, 10:25:19 AM »

I've had my 740 new since '82, and other than the compressor issue (It's been out of service for a long time for me, but then again---I have no use for it anyway!) everything that matters still works well.
The issue of the 'wonky' compressor switch for me has to do with RF out.  It would appear that the compressor switch can impact on the RF power out, so make sure that the compressor switch is EITHER IN OR OUT when you check for RF power OUT because that is an INTERMITTENT issue with this switch, and then leave it in the position that will cause the transmitter to deliver the power out.
Also, from my experience of using the radio 'portable' the screws on the two boards on top (IF and Main) could work loose and need to be retorqued, so check that.
73---Ernie
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W4UDX
Member

Posts: 21




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« Reply #25 on: April 21, 2009, 07:55:26 PM »

Both issues (compressor switch and preamp switch) are well known and documented. Google MTS - Malcolm Technical Support (Scott Malcolm, long-time Icom tech). He has info on his website about these failures and easy solutions for those who are not afraid to use a soldering iron. The IC-740 will hang in there with the modern rigs, unless you are into computer control. I sometimes miss mine, but it has been replaced by a 718 with DSP and narrow SSB filter, which is also a very good radio.
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