Let me know what the number is on the final power module.
The new Mitsubishi RA series have problems with the heat sink die not
being flat. In the center there is about a .8mm indentation for no
reason. The datasheet specify it is nessacary to mill the heat sink to
fit this, but it is not economical as each module is slighlty
different, so most just stick heatsink grease in the gap and call it
good.
I recently built a 1250 MHz amp based on the RA18H1213G and I got
metal poisioning from milling the copper die by hand with 600 grit
sand paper. But you can use a belt sander with a fine belt and where
gloves and a mask.
Repair may be possible, pop the plastic cover of the module and search
for hair line fractures like the old MA-27 in the Yaseu 5100. But
usually I have heard that the entire board cracks when something ain't
right mechanical wise in the modules.
On a related note, if the module is not getting B+ or Bias voltage it
will attenuate the incoming signal up to 60dB.
On Mar 30, 2005 8:21 PM, Paul Finch <[EMAIL PROTECTED]> wrote:
>
> Hello,
>
> Who was the person that was saying new was better than old junk the other
> day? I tried to key my 3 month old TKR-850 repeater today and it was there
> but real low in signal strength and I was only about a mile from the site.
> I knew something was wrong! Ya see I be smart about these things. Anyway
> there is no power out, this radio has been in service three months and
> broke, my Johnson's have been in service 7 plus years and no problems, yes
> new is better that old junk, right!?!?! The UHF Johnson 559 rated at 25
> watts has been running 40 for a long time!
>
> I will look into the problem and let everyone know what I find. To be fair
> about this, the other day someone turned the air conditioner in my tower
> building off and the ambient air temperature went up to 140 degrees F, but
> the Johnson's survived, go figure! Matter of fact, everything did except
> the new Kenwood.
>
> Paul
>
>
> Yahoo! Groups Links
>
>
>
>
>
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