OK, Astro folks, here is an interesting one...
I have an Astro XTS3500 with a truly annoying hum in the transmitted audio in analog mode. I'm not sure how it performs in digital mode, because I don't have any way to test it, but in analog mode I detect a hum on the receiving end of the any transmission that I make while in high power mode. If I drop to low power, the hum goes away, or even if I go into the service mode and adjust the high power softpot down. I don't have a watt meter, or a scope to check it out -- I'm using the just my ear and another radio to test the XTS. I can detect the hum even when transmitting in CSQ mode without PL or DPL. ??????
Also, the radio is considerably louder when using an external speaker mic. The internal speaker sounds great, but just isn't very loud. At full volume, I get no distortion, no plastic rumbling, and most of all, no desire to turn it down even indoors. When I compare it to my MT2000, they are about equal volume when the MT2000 is about 3/4 and the XTS is all the way up. I didn't see any rated audio alignments in the service section of RSS, so I'm assuming that this isn't easily calibrated.
Also note, I just purchased this radio and the seller assures me that the audio was normal prior to shipping it. He also explained that he noticed the hum in the audio in the past, but was able to remove it by adjusting the deviation down. I believe the seller to be telling the truth, so my question is if the problem is likely to be a hardware or alignment problem.
Any help would be greatly appreciated.... If more information is needed, please let me know and I'll provide whatever is needed. Oh yea, If it is a hardware problem that directly resulted from rough handling by UPS, and the package was sufficiently insured, will UPS repair the radio or replace it? Just curious if I should be going down that road...
-Yosh
XTS3500 Problem, please help...
Moderator: Queue Moderator
Thanks Shaun!
You are on to something here (or at least led to me find the answer, read on), and I think I figured out where the hum is coming from. After taking the radio apart, cleaning all of the contacts, making sure all of the shield were "snapped" together and then re-assembling the radio, I checked the radio and there was a small difference made to the relative volume of the hum (it went down). I found that one of the shields was not completely snapped together (other than finding a piece of wax, and some scotch tape floating around, everything looked pristine).
However, the hum was still there. Perplexed, I played around with different programming options like turning on and off the PL, DPL, CSQ mode, changed the signaling, etc. all to no avail.... Until the battery went dead....
I swapped to a JBRO NiCD (I had been testing with a W & W Mfg. NiMH), and the hum goes away. Put the W & W back on - hum comes back. So, I charged up the W & W to see if it had anything to do with voltage, and it doesn't. I have three W & W NiMH batteries and they all introduce the hum to the transmitted audio. Has anyone heard of this?????? I am assuming that the metal in the battery is picking up transmitted RF and "injecting" it into the battery contacts. I wonder if this radio is more sensitive than others, or if it is acting normally and the W & W batteries are just acting like antennas to RF???? If anyone has insight into this problem, I sure would like to hear about it. I am relieved that this may not be a radio problem - batteries are cheap
You are on to something here (or at least led to me find the answer, read on), and I think I figured out where the hum is coming from. After taking the radio apart, cleaning all of the contacts, making sure all of the shield were "snapped" together and then re-assembling the radio, I checked the radio and there was a small difference made to the relative volume of the hum (it went down). I found that one of the shields was not completely snapped together (other than finding a piece of wax, and some scotch tape floating around, everything looked pristine).
However, the hum was still there. Perplexed, I played around with different programming options like turning on and off the PL, DPL, CSQ mode, changed the signaling, etc. all to no avail.... Until the battery went dead....
I swapped to a JBRO NiCD (I had been testing with a W & W Mfg. NiMH), and the hum goes away. Put the W & W back on - hum comes back. So, I charged up the W & W to see if it had anything to do with voltage, and it doesn't. I have three W & W NiMH batteries and they all introduce the hum to the transmitted audio. Has anyone heard of this?????? I am assuming that the metal in the battery is picking up transmitted RF and "injecting" it into the battery contacts. I wonder if this radio is more sensitive than others, or if it is acting normally and the W & W batteries are just acting like antennas to RF???? If anyone has insight into this problem, I sure would like to hear about it. I am relieved that this may not be a radio problem - batteries are cheap
Yosh
I've seen this in some of my XTS3000 UHF radios when operating at the radios specified upper band edges, especially at the high end in a 450 to 520 radio, when the power was set to the maxed specified value of 4 watts, the battery voltage was dropping under 7 volts even when it was fully charged and new. This was occuring with a fresh battery and I found that the transmitter was very inefficient at the high end of the band. What model radio is it ? Check the softpot settings for power in the frequncy range where the hum is, if its above the specified setting then it could happen, it could also occur at the specified power setting, in your case it does seems to be battery voltage related. I had to stick wires between the battery contacts and then attach the battery to the radio and I put a voltmeter on these wires to see how much the battery voltage dropped in transmit, and in my case it was dropping below 6.5 volts and the hum was there.
I solved the problem by getting a higher capacity battery and by lowering the power output slightly.
Mike
I've seen this in some of my XTS3000 UHF radios when operating at the radios specified upper band edges, especially at the high end in a 450 to 520 radio, when the power was set to the maxed specified value of 4 watts, the battery voltage was dropping under 7 volts even when it was fully charged and new. This was occuring with a fresh battery and I found that the transmitter was very inefficient at the high end of the band. What model radio is it ? Check the softpot settings for power in the frequncy range where the hum is, if its above the specified setting then it could happen, it could also occur at the specified power setting, in your case it does seems to be battery voltage related. I had to stick wires between the battery contacts and then attach the battery to the radio and I put a voltmeter on these wires to see how much the battery voltage dropped in transmit, and in my case it was dropping below 6.5 volts and the hum was there.
I solved the problem by getting a higher capacity battery and by lowering the power output slightly.
Mike
Well, after a bit of testing, I am concluding that the hum is directly related to the mfg. of the battery (W & W Mfg.) and it's SOC. If a W & W battery is fully charged, then the hum is barely noticeable. As you deplete the batteries remaining capacity, the hum increases. I have found that between the three W & W batteries that I have, one is really bad, the second is OK, and the third doesn't seem to affect the radio like the others. My JBRO NiCd works flawlessly.
I'll have to do further testing like Mike above to determine if it is voltage related. I guess the W & W could have a higher internal resistance (which is consistent with NiMh batteries), and at the higher power setting causes a drop in voltage and producing the hum. I've done all of my testing at 462 MHz and at 3.9 Watts on high power.
I believe that the radio is working normally and I'm going to try a Motorola original battery to confirm this. Shall report when completed...
-Yosh
I'll have to do further testing like Mike above to determine if it is voltage related. I guess the W & W could have a higher internal resistance (which is consistent with NiMh batteries), and at the higher power setting causes a drop in voltage and producing the hum. I've done all of my testing at 462 MHz and at 3.9 Watts on high power.
I believe that the radio is working normally and I'm going to try a Motorola original battery to confirm this. Shall report when completed...
-Yosh