Icom HM-8 Microphone Use

K6QD · Post by **K6QD** » Sun Oct 19, 2008 8:05 pm

Can anyone provide info re: the HM-8 generation of DTMF codes? I have an old Icom 2M radio (IC-25A) that doesn't generate DTMF codes itself and I want to use the HM-8 to do so.

wx1f · Post by **wx1f** » Sun Oct 19, 2008 10:23 pm

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K6QD · Post by **K6QD** » Mon Oct 20, 2008 2:45 am

Thanks for the reply Gordon - You are correct. I am looking to implement the IC25A with tone capability to enable repeater access. This does not necessarily require any mods to the radio itself (such as piexx.com products) because I believe the HM-8 mic can generate these tones. The HM-8 has a 0-9 keypad which, I believe initiates generation of DTMF tones, but I do not know the relationship between the standard tones and keypad on the mic., e.g. how do I generate a 131.8 Hz tone with the HM-8?

wx1f · Post by **wx1f** » Mon Oct 20, 2008 11:54 am

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K6QD · Post by **K6QD** » Mon Oct 20, 2008 5:26 pm

Thanks! I now understand the mic. won't do what I was thinking. I have been using the 25A like you say as a packet monitor for years and simply wanted to expand it's usefulness, so no big deal.

wx1f · Post by **wx1f** » Mon Oct 20, 2008 5:56 pm

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K6QD · Post by **K6QD** » Mon Oct 20, 2008 11:36 pm

Thanks again Gordon. There are two Packet sites left locally, but I have used Internet cluster sites for the past 3+ years. For the $, Pixx is surely viable. 73 -

k9yli · Post by **k9yli** » Thu Oct 23, 2008 3:26 pm

[ I get tone boards from AES.. single tone board is about $21.
most locations have same tone for most local repeaters.

Or a very small 6 position dip switch will allow changeing tones. but you need a cheat sheet to do it.
Also Marlin jones (mpja.com) has both screwdriver and thumb wheel
binary switch if you wanted and external switch pack along side the radio.
still need the cheat sheet..

K6QD · Post by **K6QD** » Thu Oct 23, 2008 4:07 pm

And... The "cheat sheet" comes from?

k9yli · Post by **k9yli** » Sat Oct 25, 2008 2:45 pm

QD
the cheat sheet comes with the tone genertor.

you solder jumpers (6 possible) to get the available tone you want.
If you wire in binary switches to allow you to change the tone, you need the cheat sheet as no one could remember the
conversion of binary code to tone freq.

binary code of 6 gives you possible

64 possible selections.

32 16 8 4 2 1 added together get 64.

0 0 0 0 0 1
0 0 0 0 1 0 etc.

i beleive also it is wired by "not" logic....

a jumper equals zero no jumper equals 1

the MPJA switches have both the true position and the compliment position
contacts so easy to wire up..

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Icom HM-8 Microphone Use

Icom HM-8 Microphone Use

Re: Icom HM-8 Microphone Use

Re: Icom HM-8 Microphone Use