BAD Problems with XTS3000

[fireradio]

Well, my almost-new XTS3000 came in the mail today! Yay! But guess what? Something isn't quite right with it Here's the deal...

It's an 800 MHz H09UCH9PW7BN with Host 7.00.02, DSP 7.03.06, and a FACTORY flashcode of 5000080000001, meaning it has IMBE/Proj25, Smartzone, Digital ID Display.

The problem is while transmitting, there is a HORRIBLE hum in the background. My voice is barely heard at all on another radio (analog). When I go into digital mode, the hum is so bad that you can't hardly hear the usual data (P25) sound. I haven't really been able to test RX, since the radio hasn't been programmed, but I think that is ok. Everything else about the radio seems fine. What is wrong???? Please help...

Thanks!!

Oh yeah, I tested it with a speaker/mic and had the same problems. No difference...

[XDCLabs.COM]

Q - Btw, with that Host/DSP combo.. Can you use DOS RSS still?
A - Yes

[XDCLabs.COM]

M uses a 3 part version numbering scheme separated by "."s

If the first one denotes Major new features. In your case, you have the capability of APCO OTAR, Omniling, encrypted APCO data, etc. Whether you have them enabled is another story. The second part indicates minor features or major bus fixes. The third part indicates bug fixes. Actually this is more or less of an industry standard in the software world.

Unless you desperately need the new features (which will require flash upgrading as well for the codeplug), I'd say don't upgrade.

[fireradio]

Well, I've got a stubby antenna -- so, I'll try to swap it out w/ a long one at work tomorrow. I had no idea that a stubby antenna alone could do that. I know they suck, but I never have heard of that. The weird thing is public safety in this area all use XTS3000's (analog and digital trunked) and on analog I've never heard a hum ... I didn't even know there was supposed to be a problem like that w/ the XTS's. Anybody else have any other ideas? I'll let you all know how it works tomorrow...

I haven't had a chance to program the radio yet, so I don't know about the DOS RSS...all I have is the CPS anyway..

Thanks!!

[Yosh]

My XTS3500 UHF buzzed like crazy when I was using W & W NiMh batteries. I switched to a JBRO and the hum went away. I believe that the problem (in my case) related to RF as well as internal resistance and the associated voltage drop during transmit. I could move my hand around the radio and the hum would get worse or better depending on where the it was. Fully charged batteries made a bit of a difference, but nothing major.

-Yosh

[fireradio]

I've got a Motorola NiCD battery with a date code of 137. I'll see if I can come up with another battery and try that, but I think the problem is something else

Thanks

[mike m]

While your searching for the buzz how about checking the band edges and the middle of the rptr input and the talkaround frequncies and see if your XTS3K has terrible second harmonic rejection. I have 3 xts3ks that have harmonics that are in the -48 to -52 dBc range around 821 and 852 MHz. Quit a bit out of the spec'd -70 dBc. This is using a 30dB pad at the radio antenna port and the same results going into 3 different HP70000 series spectrum analyzers, so I doubt measurement problems.


Mike

[mike m]

While your searching for the buzz how about checking the band edges and the middle of the rptr input and the talkaround frequncies and see if your XTS3K has terrible second harmonic rejection. I have 3 xts3ks that have harmonics that are in the -48 to -52 dBc range around 821 and 852 MHz. Quit a bit out of the spec'd -70 dBc. This is using a 30dB pad at the radio antenna port and the same results going into 3 different HP70000 series spectrum analyzers, so I doubt measurement problems.


Mike

[fireradio]

Thanks everyone for your help! Unfortunately, I just couldn't find the problem (and neither could anyone else...) So I returned the radio, and I have another one coming to me shortly.

Thanks again!