I have moved several GE Mastr II 40 watt units up from the 417 mHz area to the
440 mHz area as repeaters. The exciter tunes up OK to the higher frequency,
but the receiver front end and LO multiplier will not tune. I use LOW side
injection for the LO string and modify the helical resonators in the front
end. I remove all the helical resonator coils and remove one quarter turn from
each coil to get it to tune up into the 440 band. The modified receiver will
tune from 420 through 450 with this mod. A better approach is to obtain a
450-470 mobile and exchange the LO and front end modules. No modification is
required to the helical resonators on the 450 to 470 radios. Be sure to use
HIGH side injection for the receiver with the 450-470 front end.
On the low pass filter for the transmitter, I paralleled a #20 bare wire with
the wire already in place coupling the sections of the filter together and the
reduced inductance moves the filter up enough into the band to pass 450 with no
problem. I did not change anything else in the amp.
73 - Jim W5ZIT
--- On Tue, 3/10/09, iamcranked <la...@thunderbolt.net> wrote:
From: iamcranked <la...@thunderbolt.net>
Subject: [Repeater-Builder] GE mastr II station PA
To: Repeater-Builder@yahoogroups.com
Date: Tuesday, March 10, 2009, 3:55 AM
I am looking for some help with a UHF GE Mastr II base I just
acquired. I've never worked on one of these before and have no knowledge as to
what mods need to be done. My unit currently is on 416.550 and I need to move
it up to 444.425 but have some questions before I begin. My biggest concern is
about the Power Amp.
I have a 19D321347 G5 Rev N PA board which according to LBI-30213E is a 406-420
Mhz 40 watt PA. There seems to be another version of the same board number
except it is a G9 and the LBI says it is for 420-450 Mhz but I can't find a
listing with the differences between them. The LBI shows both G5 and G9 range
boards with the same components listed as the (LL) designation supposedly
covering the entire 406-450 range.
Can anyone enlighten me as to the difference between the G5 and G9 version of
the 40 watt PA?. Will the 406-420 PA board work in the 444 range? If not can
anyone advise what mods need to be done so it will?
My PA also has a 19D327024 G1 filter which shows it is used in both the 406-420
range as well as 420-450 range. However when the G9 version of the PA board is
used it shows it covers 420-450 Mhz.
Will I need to mod the filter to get the 444 Mhz signal to pass?
There again I find no differences to the filter board when used in the
different segments.
I appreciate any help
Larry - N7FM
