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Author Topic: IC-47A tones???where did they go?  (Read 7105 times)
KA4AQM
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Posts: 108




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« on: November 28, 2017, 02:52:17 PM »

Recently bought a great little IC-47A, but it will not access the local repeaters with tones. Short of digging into the radio, how can I chk for tones being transmitted? Simplex works fine. Perhaps tone generator is shot or missing, but the word TONE shows up in orange on the face telling me I can select TONE, but I think the tones are not going out. ANY help would be appreciated. 73, Randy, KA4AQM
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WB6BYU
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« Reply #1 on: November 28, 2017, 03:31:41 PM »

Did you set it to the right tone frequency?

I have the manual for the 2m IC-27A in front of me, and the tones are set by number.  You need a
copy of the manual to know which tone number corresponds to which tone frequency.

And, while the manual says  you can save the tone setting in memory, that may just mean that you
can save the tone ON/OFF setting.  Based on my experience with this and the later IC-28, it wouldn't
surprise me if you still have to set the actual tone frequency manually each time you switch to a
different repeater, rather than relying on the tone frequency being stored in memory.  (At the time
these rigs were made, access tones weren't as common as they are today.)

You can't test the tone in simplex mode because the radio only transmits tone in duplex mode (even
when the TONE light is on.)  However, if you can listen directly to the output of the radio in duplex
mode, you can set the tone number to something between 39 and 55, and you should hear an
audible tone on the output.

It is possible that something is wrong with the tone generator, or more likely that the tone deviation
control is set wrong (either too little or too much deviation when the tone is generated.)
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KA4AQM
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Posts: 108




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« Reply #2 on: November 28, 2017, 04:20:54 PM »

Thanks wb6byu. My original 2M rig when first licensed in 1979 was (and still being used) is the ic-27A. Very familiar with the radio, programming, memory, and all that.  I have hit cpu reset twice. I know numbers are used for tones, etc. I have listened to output in simplex and duplex on another radio....like I said, simplex it does great. My thoughts are leaning towards tone generator. I’ve sent text to previous owner asking if he knew anything about this deficiency. I have full manuals for both -27 and -47, great radios. Was just trying to throw a line out for ideas. Again, thanks for the ideas....do you still have the 27a?
Randy
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K5LXP
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« Reply #3 on: November 28, 2017, 05:29:00 PM »

Wouldn't be hard to pop the cover and make sure the tone IC is installed.  Guessing you don't have a service monitor but if you could lay hands on a basic scope, even a soundcard scope you can install for free, you could poke at the encoder circuit and see what if any tones it's generating.

Mark K5LXP
Albuquerque, NM
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KA4AQM
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Posts: 108




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« Reply #4 on: November 28, 2017, 06:02:06 PM »

Thanks Mark.....still scratching my head, waiting for an epiphany   Smiley
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N1CX
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Posts: 338




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« Reply #5 on: December 25, 2017, 01:56:18 PM »

HRO special on 2m Yaesu 80w mobile right now $129 good deal LOL

Love those old icoms. Sometimes its better to walk away though..food for thought depending on how deep you get into it.
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N1CX
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« Reply #6 on: December 25, 2017, 02:02:47 PM »

I started with a Regency HR2B and then a GLB synthesizer add-on. That was cutting edge stuff back then  Grin I had a 22s, several 25a, 27a, many more. Cool old radios for sure. Find someone with a tone decoder or a service monitor such as an ifr etc. You should be able to tell if it has pl or not. If you select a higher frequency many times you can hear it in the background depending on it's level. 250hz area.
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KA4AQM
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« Reply #7 on: December 27, 2017, 02:06:29 AM »

K5LXP...Mark, I opened case. Appears tone encoder chip is in there. I’ve programmed all memories with local repeaters and continued to try and open the closest one, but no dice. I can still use radio to hear 440, but like many communities, 440 is low activity so no real loss here. I use an FT60R as a backup if I want to get into repeater. Just wish I could get this great little radio to transmit tones. Thanks for all the suggestions.
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K5LXP
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« Reply #8 on: December 27, 2017, 08:08:20 AM »


Do you have, or can lay hands on an oscope?  Seems it'd be a fairly direct process to trace down where the tones are being generated, and where they stop.  I went through this a while back getting my own "vintage" 2m rig on the air with tones.  Mine is a Kenwood 7400 and the tone generator on that rig was just an op amp oscillator you tweaked a trimmer until you got close enough to trip the repeater.  Maybe that was good enough in the '70s but I decided to put a tone module from a commercial radio in it, and as a result I had to scope out the various signal paths and get the levels straight.  The 47A tone circuit is very simple, I bet you find the problem very quickly with a scope.

Mark K5LXP
Albuquerque, NM

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G7WFK
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« Reply #9 on: December 27, 2017, 01:24:38 PM »

As you have an FT60, would have thought the simplest test was to set it to T SQ and see if the IC 47 can open the squelch.
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WB6BYU
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« Reply #10 on: December 27, 2017, 01:29:50 PM »

The high tone numbers (39-55 or so) generate audible tones, and may
be the easiest for debugging since you can detect them with high impedance
headphones or an audio amp.

There should be a tone deviation adjustment somewhere - the pot may be
turned down, or may have a dirty wiper contact.  In my experience that would
be the most common cause of failure.

(I've also encountered a problem with the tone being turned up too high:
it would trip the repeater, but the tone would overdeviate and mask the voice.)
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KA4AQM
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Posts: 108




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« Reply #11 on: December 27, 2017, 02:00:39 PM »

WB6BYU-
In fact, right next to the Tone encoder chip is a pot (R96) called the tone deviation adjustment. I was tempted to just adjust the pot back and forth a little and then put it back in it's original position....what could it hurt? Of course I didn't have that "what could it hurt" epiphany until I had closed everything back up. I need to find/borrow a freq/tone detector locally. I've seen the cheap ones on YOUTUBE where they detect freq and the tone on one screen, really neat. Think I will put out a club call to see if anyone has one. That way I can make the R96 adjustment and see if that does anything....stay tuned! And thanks!
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AC7CW
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« Reply #12 on: December 27, 2017, 02:29:26 PM »

Some handhelds will scan to find the tones. You might borrow one of those.
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Novice 1958, 20WPM Extra now... (and get off my lawn)
WB6BYU
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« Reply #13 on: December 27, 2017, 05:05:31 PM »

Just listen to your transmitted signal on your HT.

If you have it set for one of the audible tones you should hear it.
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AC7CW
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« Reply #14 on: December 28, 2017, 09:38:25 AM »

Just listen to your transmitted signal on your HT.

If you have it set for one of the audible tones you should hear it.

He still won't know exactly what tone is being transmitted. What if the tones basically work but the programming is off and it's sending the wrong tone?
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Novice 1958, 20WPM Extra now... (and get off my lawn)
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