ctcss tone levels - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: January 25, 2020, 01:56:46 pm
content: Hi all,ive just fitted a ctcss board to my radio,it opens the repeater fine but get horrible audio reports,would a too high ctcss input to the dev pot cause this?,its fine simplex.

author: TheMG
author_rank: Frequent Contributor
timestamp: January 26, 2020, 01:10:11 am
content: The CTCSS tone deviation should be at least 500Hz but no greater than 1Khz. If it's too high it leaves not enough room for the voice modulation and you end up with distortion.

author: CaptDon
author_rank: Super Contributor
timestamp: May 19, 2020, 01:26:45 am
content: Can you monitor your transmit audio with another radio??If you sound like the Yellow M&M talking through the fan bladeson the old TV commercial then yes, the tone level is too high!!!

author: vk6zgo
author_rank: Super Contributor
timestamp: May 19, 2020, 12:23:13 pm
content: The last time I installed CTCSS, I had a Deviation meter, but no more.The usual trick is to send a very low level, & see if it will trigger the repeater.If not, increase it slightly & try again, until it does.Tweak the level back & forth till it consistently triggers the repeater, checking all the time that the CTCSS tone does not become noticeable when listening to your transmission.

author: m3vuv
author_rank: Super Contributor
timestamp: May 20, 2020, 09:20:41 am
content: ive been told its due too the node/gateway i tx into is set to narrow fm not wide,the only thing i can change is the dev pot,is there a way to mod the radio to have a switchable wide or narrow fm on tx?,cheers m3vuv.

author: christopher iles
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:27:32 am
content: Hello,Where have you connected the output of the CTCSS to?It should normally be connected to the wiper of the deviation pot and not onto the mic audio.If you have connected everything correctly, disconnect power to the CTCSS board and check your transmitted audio.If it returns to normal, you may need to re-route and/or screen your wiring.A spare radio to monitor your own transmission will be invaluable to nail this one.Kind regards,Chris. G0VOE.

author: m3vuv
author_rank: Super Contributor
timestamp: May 21, 2020, 12:44:29 pm
content: it goes to the middle leg of the dev pot,i cant tell if the audio is better with the tone board disconected as i need the tone to open the node,its like the node clips my audio

author: vk6zgo
author_rank: Super Contributor
timestamp: May 21, 2020, 01:05:08 pm
content: Can you tell us more about this "node/gateway"?The reason I ask, is last time I retro fitted a CTCSS generator, was to a FT290R to access a 2m FM to 10m FM "gateway" which had a brief "vogue" back in the late 1990s.I set the correct CTCSS frequency & deviation in my lunchtime at work,with trustworthy equipment.I got into the "gateway" but my signal was reported as "sounding a bit off frequency".I checked the radio transmit frequency & sure enough, it was "a bit off".I had not had any problems on repeaters, or simplex, but it looks like the gateway was more critical.Perhaps it didn't demodulate the signal down to baseband audio, like a normal repeater, but was a translator, so my "off frequency" condition was more critical on 10m, where the deviation was narrower.

author: CaptDon
author_rank: Super Contributor
timestamp: May 21, 2020, 02:36:33 pm
content: I also wonder if that deviation pot sets both the mic audio devand your ctcss? Perhaps the ctcss board is messing with the micaudio at this summing point? I make the guess that the radiosounded fine prior to adding the ctcss modification?

author: m3vuv
author_rank: Super Contributor
timestamp: May 21, 2020, 04:42:13 pm
content: ive not heard it myself but the folks tell me my audio sounds clipped.