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Author Topic: How well do IC-756s and IC-7600s work on RTTY  (Read 3396 times)
K0OD
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« on: April 13, 2009, 10:48:08 AM »

I'm thinking of buying Icom's month-old IC-7600 or perhaps the recently discontinued 757PRO III. I know very little about digital modes. I doubt I'd be a heavy user in any event.

How well does the latest 756 do on RTTY and PSK? Does anyone have thoughts on how well the 7600 might do? My special area of interest is low band DX and a bit of contesting.

Thanks
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AA4PB
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« Reply #1 on: April 13, 2009, 06:35:42 PM »

The PRO is a great RTTY rig capable of 100% duty cycle. I expect the 7600 will be as well. You want to use sound card software however with either AFSK or direct FSK keying for the transmitter. The on-screen receive display isn't too practical, at least on the PRO.
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K0OD
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« Reply #2 on: April 13, 2009, 08:08:09 PM »

I was referring to the inherent ability of the 756 to work RTTY and the 7600 to work both RTTY and PSK. The new 7600 features a front panel USB jack that directly accepts a simple USB keyboard. Its built-in monitor is small of course.

Are you saying that any kind of serious digital work would still require use of a computer so that the digital capabilities of those radios are pretty worthless?

I was especially wondering how well those radios print weak RTTY signals under difficult conditions.  

 
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AA4PB
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« Reply #3 on: April 14, 2009, 06:50:16 AM »

The 7600 with its keyboard ability is a little more useful. I've only tried the built-in RTTY receive capability of the PRO a couple of times just to see if it works. Personally I don't find much use for watching text scrolling across the small screen and no transmit ability. In my opinion, most serious RTTY people would want a larger screen to view more lines of text plus the memory and file capabilities that a computer program offers. So, from my prospective the built in RTTY capability of the PRO is a non-starter that really doesn't offer much practical capability to the radio. Someone who only wants to occasionally monitor some RTTY and doesn't have a computer available in the shack might find it useful.

As to the question of whether the built in decoder can copy weaker signals than a sound card program, I seriously doubt it - but I haven't done a side by side comparison. I find the biggest issue is not weak signal reception, but rather the ability to avoid interference from adjacent stations and the receiver's IF filters are the biggest help there, regardless of what you use to decode the signals.
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AA4PB
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« Reply #4 on: April 14, 2009, 06:57:22 AM »

In regard to PSK31, unless the 7600 has a waterfall display that lets you see all the activity and select the signal you want to copy, you'll find it really limiting. It's a real pain to try to tune in a PSK31 signal with the VFO. We used to do that when PSK31 first started but there weren't many stations on the air then. Now with all the PSK31 signals stacked right next to each other it would not be much fun :-)

Again, computer software has a lot of other features to offer like CQ, memory, and file functions that may not be implemented on the 7600.
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VA7CPC
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« Reply #5 on: April 14, 2009, 07:53:59 AM »

I think the 756 ProIII is one of the few rigs with "twin peak" filters (implemented in the IF DSP) for RTTY.  A friend, who runs a big contest station, has several of them, and says they're as good as you can get for RTTY.  I don't know about the IC-7600.

For RTTY contesting -- even "light contesting" -- a computer running contest-logging software (e.g. N1MM Logger), with a waterfall display, is your best friend.  

       Charles
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AA4PB
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« Reply #6 on: April 14, 2009, 10:12:19 AM »

Yes, but you can run the twin peak IF filters and still use external computer decoding software. It's the built-in decoder and display that I question the value of - not the twin peak filters.
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K0OD
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« Reply #7 on: April 14, 2009, 10:24:38 AM »

AB4OJ's detailed review of the 7600 says:

re:PSK
"The vector diagram, FFT scope, AFC menu and waterfall display to the right of the encode/decode text field greatly facilitate correct tuning. With a keyboard plugged into the front-panel USB port, the IC-7600 becomes a self-contained PSK31 and RTTY terminal. The IC-7600 decoded weak (S1 to S2) 20m PSK signals reliably..."


re; RTTY
"The familiar tuning-bar display together with the FFT scope and waterfall display to the right of the encode/decode text field, make correct tuning very easy...especially when using the Twin Peak Filter"

Sounds good, right?
 
http://www.ab4oj.com/icom/ic7600/7600notes.pdf
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AA4PB
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« Reply #8 on: April 14, 2009, 01:24:02 PM »

Yes, it sounds like Icom has made a lot of improvements to the 7600 over the PRO. One question I would have is whether it provides any facility for recording and playing back "canned messages" and whether there is any way to save received data, call signs, etc. If not then I still think you are ahead using a computer, unless of course you don't have or don't want a computer in the shack.

To me, one of the benefits of digital modes are things like call sign capture, hit a key to send the call exchange, bult-in logging, etc. How would you handle an RTTY contest with just a radio and keyboard? You'd spend a lot of time typing CQ and I keeping a log by hand.
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K0OD
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« Reply #9 on: April 14, 2009, 04:24:42 PM »

"Built-in memory keyer provides 4 channels for CW mode and 8 channels each for RTTY and PSK31 modes, capable of storing up to 70 characters for each channel. The memory keyer is useful for sending CQ or exchanging numbers during contests. When not contesting, you can store and send your name, QTH, rig, etc, With a USB keyboard, you can send memory contents using function key on the keyboard."


Here's a link to complete specs and a link for downloading the manual:
http://www.icomamerica.com/en/products/amateur/hf/7600/default.aspx

I don't know how the capabilities of the 7600 compare with the 756PROIII. I presume the 7600 offers more plus the new PSK ability.  The 7600 can save received signals into the USB memory.

Quickly scanning the manual, I see where serial numbers can be injected on CW. Don't see anything about that on RTTY or PSK.
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AA4PB
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« Reply #10 on: April 15, 2009, 05:43:51 AM »

I guess *my* bottom line is this: Would I purchase a 756PRO or an IC7600 simply because it had built in RTTY or PSK31? No way. I'd certainly purchase it because it is a good radio (I've had the 756PRO since it first hit the market) but the RTTY and PSK31 feature would have little influence because you can get much more digital capability from a computer program (even a free one). I really don't think the built in digital modes on the 7600 will copy signals any better than using a properly interfaced digital computer program with the same radio.
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N0ZLD
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« Reply #11 on: April 29, 2009, 06:43:32 PM »

Hope this helps, a picture is worth a thousand words

http://www.icom-france.com/files/IC-7600_keyboard.jpg
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K4FX
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« Reply #12 on: April 30, 2009, 09:14:05 AM »

I have been into RTTY for some years now and used many different radios, my current rig is a Pro II, I don't think there is a huge amount of difference (other than tx memories) on RTTY between it and a Pro III. It is by far the best RTTY I have ever used. The PA is solid as a rock, full 100w in contests without a whimper. I have checked the on-board decoder against MMTTY many times (free program and the best IMHO) and they are always extremely close. When there are errors, they are usually the same wrong character.

Like the other poster said, it's better to use a PC sound card for convenience. In my case I am logging to the PC anyway, so its a lot easier for me to have the data there to begin with. It would be a pain to have to retype the call into the logging program, especially when contesting!  But I must say it would be nice to have that USB keyboard feature as a backup in case the PC crashed just as some rare country came along.

The twin peak filter is wonderful, I can work contests comfortably under conditions that would have wiped me out on previous rigs, that TPF at about 250 hz is awesome.

I would recommend FSK over AFSK, before the Pro I had a Flex SDR-1000, lack of FSK is why it is gone, Another thing about the Pros (and most Icoms) They are very easy to interface to the PC. You do not need to spend money on a rigblaster for FSK keying, with 2 NPN transistors and 2 1K resistors you can set up a nice FSK/PTT interface, (see http://www.aa5au.com/rttyinterface.html)

Don AA5AU is well-known as one of the better RTTY contest ops around and he says the Pro III is the best rig he has operated, Icom sent him a pair of them to try out just to convince him how good they were, now he owns one. Check out his opinion of the Pro at http://www.aa5au.com/rtty_radios.html

You will enjoy RTTY, it is my favorite mode by far, and you will find some really nice people on that mode.

Look forward to working you there!

73

Bill K4FX


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ZS1SA
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« Reply #13 on: June 01, 2010, 08:08:48 AM »

I have only been using the 7600 for about a month now but I can confirm that it does have a waterfall display, and there are 8 programmable brag tape memory's (sorry, old terminology) each for RTTY and PSK operation. You can select the WIDE mode which makes the waterfall display and received text window screens much larger, causing the S meter and other information normally on the screen to shrink down in size. And the big plus......no computer noise from the PC.
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W5LZ
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« Reply #14 on: June 05, 2010, 05:59:36 AM »

Very simply, if it's built-in to a radio it typically won't have all the 'features' a computer program will have.  That doesn't mean that using a computer is the only way to do it, just that there are more 'bells-n-whistles' available.  And of course, there's also all the typical 'catches' when using a computer with a radio, as in they typically don't 'like' each other.  So, select the method you would rather contend with.
Paul

And naturally... If you ain't got Kenwood, you got squat!  Wink
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