Spectra VHF Help

glock318 · Post by **glock318** » Sat Feb 25, 2006 5:39 pm

Hello,

I just recived a 110 watt vhf spectra from a fellow that had a kenwood tk-790 100w, and a vhf spectra 110w mounted in his truk, He had the antennas 1/4 wave spaced about 6" apart on the roof. I dont know how long he had it like that but , He said that he started to notice that he could not recive well at all anymore. Well when I found out that he had the antennas spaced 6" apart I knew that the feedback from the 100watt antenna had to be feeding back through the other radio. So my question is what does it hurt when it feedsback through like that? The Rf board ? Next question I dont have a schmatic so I dout I can fix it. IF any one here can help me please send me a pm Thanks in advance!

kcbooboo · Post by **kcbooboo** » Sat Feb 25, 2006 5:45 pm

Probably some front-end protection diodes (if present) or the RF amplifier transistor. They're all probably surface-mount components. Not much else usually goes wrong due to an overload.

Bob M.

glock318 · Post by **glock318** » Sat Feb 25, 2006 5:49 pm

Thanks I'll check them Thank You

Will · Post by **Will** » Sun Feb 26, 2006 12:08 am

kcbooboo wrote:Probably some front-end protection diodes (if present) or the RF amplifier transistor. They're all probably surface-mount components. Not much else usually goes wrong due to an overload.

Bob M.

Bob is correct. The RF amplifier for the receiver is mounted on a cerramic substrate and it is diffacult to replace. The cerramic sinks the heat making surface mount rework/repair very diffacult.

Most of the time based on hundreds of Spectra repairs, RF overload causes the RF shunt diode on the TA PA shorts out. This can be checked with an ohm meter. There have been some failure of the RX RF amp transistors also.