“New” KI4IJQ Repeater

So I finally got around to working on the permanent 147.180Mhz repeater… originally the 147.345Mhz repeater this was supposed to be the permanent repeater, the current one was just temporary… so after 5 or so years in service I figure its about time the real one went up :)

KI4IJQ repeater

so here is the basic layout of the repeater… from top to bottom

1) Audio Compressor – Will normalize (expand/compress) incoming audio before the repeater controller
2) Arcom RC-210 repeater controller – Not sure if this will be the final controller, thinking of getting an S-Com 7330 since I am not totally happy with the Arcom
3) Audio panel – this panel just has a speaker, volume control and selector switch that lets you listen to the audio coming out of each receiver
4) Receiver Voter – basically an audio comparator, as part of a voting system the voter is what decides which receiver is getting the “best” signal and “votes” it, aka passes the audio to the controller
5) Mastr III – this is the actual VHF 2M repeater…
6) Mastr III Receiver Shelf – this has 2x UHF receivers for the satellite receive site links
7) Mastr III Receiver Shelf – this has 1x UHF receiver for satellite receive site links
8 ) UHF Preamplifier/multi coupler – shares one UHF antenna to the 3x UHF receivers
9) Fuse Panel – distributes the high current 12V to all the low current 12V equipment
10) 12V high current power supply – powers everything in the shelf minus any power amplifiers
11) 26V high current power supply – powers the Mastr III VHF PA
12) VHF Mastr III PA – 10mW in 110W out – set to 15W out via software PA pot setting… will be driving a 250W TPL PA

so first thing I had to do was program the all the shelfs…

Mastr III software

mmm DOS

then tune the RX Synthesizer modules…

Mastr III RX Synthesizer module

Red light indicates no lock. There is a tunable capacitor to tweak the VCO.

Mastr III RX Synthesizer Module in Extender Card

using an extender card you tweak the VCO until the red light turns off… then you have to tune the front end…

Mastr III RX Front End

basically a 5 slug filter in front of the receiver to increase selectivity

Mastr III RX Front End

tuning it requires the use of a signal generator… as you get closer to getting it properly tuned you keep turning down your signal until you get it to “ideal”… which ideally should be at -120dBm or better

next up is the transmitter

Mastr III TX test

using the Mastr III DOS software and the PA PWR setting I tuned the Mastr III’s PA to 15W so it could drive a secondary PA, a 250W TPL

I did this for 2 reasons, 1 the Mastr III PA is a lot more difficult/expensive to repair/replace than the TPL, so the TPL will act as a “sacrificial lamb” if anything catastrophic happens to the repeater… 2 once the system gets its satellite receive sites its receive footprint is going to be pretty large, so we need to compensate with more transmit power

VHF Mastr III repeater

done for now… all thats left is to use the service monitor and a TIMS set to set all the audio levels

Wednesday, June 15th, 2011 Amateur Radio