[ICOM] PBT Mod and questions

[Adam Farson]

Hi Frank,

Many thanks for the heads-up. I had understood that the Data Level and PBT
pots differed in resistance value. I wonder why the filter was pulled; this
would degrade the adjacent-channel selectivity and close-in dynamic range of
the receiver. This is almost as bad as the "IF Shift" mess in the IC-765,
which bypasses the 9 MHz filter when activated.

Cheers for now, 73,
Adam VA7OJ/AB4OJ
 
-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of Frank A. Ellis
Sent: 25 March 2006 14:02
To: ICOM Reflector
Subject: RE: [ICOM] PBT Mod and questions

Hi Adam,

In the -x75 series radios, the center-detented PBT pot was left as is (i.e.
not replaced with a non-detented
pot) but was re-wired and re-labeled as "DATA LEVEL", so there was no
"missing control" to reinstall if PBT was reinstated. It simply has to be
re-wired back to the original configuration. In addition, the -x75
PBT-enabled radios had a MuRata CFJ455K (-5 version I
believe) installed at the 455 KHz IF. This filter was removed and a small
capacitor was installed in it's place to restore the signal path in the
non-PBT radios. So, in the -x75 series radios without PBT, there was
additionally a stage of selectivity missing, along with no PBT.

73 Frank W3UHF



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