|
Did try the volume this evening...I was only able to decode packets
with the volume at least 3/4ths. And even then it wasn't packets from the local repeater, but from my Yaesu in the other room. Mike- That gets back to the +5KHz question. Have you ever had the frequency of the IC-2N adjusted? If it is like the IC-2A, there is one master crystal oscillator that sets the receive frequency, and three oscillators that set transmit minus, transmit simplex and transmit plus offsets from the receive oscillator. If the receive oscillator was off frequency, and you had adjusted a transmit offset oscillator to bring it back on frequency, then the receive frequency would still be off. Try setting the receive frequency 5 KHz higher and lower using the thumbwheel switches, and see if either makes an improvement. That would tell you the radio needs alignment. 73, Fred, K4DII |
Did try the volume this evening...I was only able to decode packets
with the volume at least 3/4ths. And even then it wasn't packets from the local repeater, but from my Yaesu in the other room. Mike- That gets back to the +5KHz question. Have you ever had the frequency of the IC-2N adjusted? If it is like the IC-2A, there is one master crystal oscillator that sets the receive frequency, and three oscillators that set transmit minus, transmit simplex and transmit plus offsets from the receive oscillator. If the receive oscillator was off frequency, and you had adjusted a transmit offset oscillator to bring it back on frequency, then the receive frequency would still be off. Try setting the receive frequency 5 KHz higher and lower using the thumbwheel switches, and see if either makes an improvement. That would tell you the radio needs alignment. 73, Fred, K4DII |
In article ,
Radioactive Man wrote: Well, I should point out that I'm not using a regular TNC. I'm using this: http://www.ringolake.com/pic_proj/zcd/zcdmodem.html It has worked very well with my little mighty Yaesu VX-2R, just not with the Icom IC-2N. Did try the volume this evening...I was only able to decode packets with the volume at least 3/4ths. And even then it wasn't packets from the local repeater, but from my Yaesu in the other room. This mdemless TNC design looks to me as if it might be rather vulnerable to the presence of high-frequency noise in the audio signal. It's not using conventional bandpass detection, but is using a simplified zero-crossing detector. High-frequency audio noise could cause spurious zero crossings, which the firmware in the onboard PIC might not be filtering out adequately. The IC-2N may have a "hotter" receiver section which could be passing through more noise from weaker packet stations. First thing I might try would be adding a low-pass RC filter - one or two stages - with a cutoff frequency of 2500 or 3000 Hz. Adding a series capacitor to act as a high-pass filter at 800 - 1000 Hz might also help. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
In article ,
Radioactive Man wrote: Well, I should point out that I'm not using a regular TNC. I'm using this: http://www.ringolake.com/pic_proj/zcd/zcdmodem.html It has worked very well with my little mighty Yaesu VX-2R, just not with the Icom IC-2N. Did try the volume this evening...I was only able to decode packets with the volume at least 3/4ths. And even then it wasn't packets from the local repeater, but from my Yaesu in the other room. This mdemless TNC design looks to me as if it might be rather vulnerable to the presence of high-frequency noise in the audio signal. It's not using conventional bandpass detection, but is using a simplified zero-crossing detector. High-frequency audio noise could cause spurious zero crossings, which the firmware in the onboard PIC might not be filtering out adequately. The IC-2N may have a "hotter" receiver section which could be passing through more noise from weaker packet stations. First thing I might try would be adding a low-pass RC filter - one or two stages - with a cutoff frequency of 2500 or 3000 Hz. Adding a series capacitor to act as a high-pass filter at 800 - 1000 Hz might also help. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
I found a picture of the IC-2AT at RigPix and, yes, my IC-2N looks a
lot like that except mine has no keyboard. And mine looks exactly like the IC-2E, except instead of the 5k/0k switch mine says Dial/Main. Mike (Fred McKenzie) wrote in message ... I recently got two older Icom IC-2N HTs (2 meter) for use in decoding APRS packet radio. Nice radios, but I get less than 10% of packets decoded with either radio. Mike- I agree with Dave's assessment of your problem. My first thought was to turn down the audio level and see if that improved things. Otherwise, check to be sure your +5 KHz switch is off (or on if appropriate). Back around 1990, I had an IC-3AT and an IC-2AT connected in an experimental dual TheNet node, connecting between a 220 backbone network and local access on Two Meters. I never had a problem like yours. I'm not familiar with the IC-2N. Could it be a variant of the IC-2A? If not, then it is possible that model had a differently wired earphone jack, with a DC voltage on the shield terminal rather than ground. In that case, there could be a short circuit when connected to a TNC that had its ground also connected to the co-ax shield on an external antenna. I know this could be the case with some Radio Shack handheld radios, but have never encountered it with Icom. 73, Fred, K4DII |
I found a picture of the IC-2AT at RigPix and, yes, my IC-2N looks a
lot like that except mine has no keyboard. And mine looks exactly like the IC-2E, except instead of the 5k/0k switch mine says Dial/Main. Mike (Fred McKenzie) wrote in message ... I recently got two older Icom IC-2N HTs (2 meter) for use in decoding APRS packet radio. Nice radios, but I get less than 10% of packets decoded with either radio. Mike- I agree with Dave's assessment of your problem. My first thought was to turn down the audio level and see if that improved things. Otherwise, check to be sure your +5 KHz switch is off (or on if appropriate). Back around 1990, I had an IC-3AT and an IC-2AT connected in an experimental dual TheNet node, connecting between a 220 backbone network and local access on Two Meters. I never had a problem like yours. I'm not familiar with the IC-2N. Could it be a variant of the IC-2A? If not, then it is possible that model had a differently wired earphone jack, with a DC voltage on the shield terminal rather than ground. In that case, there could be a short circuit when connected to a TNC that had its ground also connected to the co-ax shield on an external antenna. I know this could be the case with some Radio Shack handheld radios, but have never encountered it with Icom. 73, Fred, K4DII |
|
|
All times are GMT +1. The time now is 04:02 PM. |
|
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
RadioBanter.com