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low cost 2m portable repeater

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dy2mpl

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hi to all,
i am an amateur radio enthusiast and i want to build a simple low cost 2m portable repeater to be use by our group of amateurs can anyone help me?please do include an schematic diagram of the circuit, tnx and good day to all
 
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The words Simple, Lowcost, and Portable are not usually used in connection with 145Mhz repeaters.

First of all we will disregard the licencing issues, I dont know how it works in your country.
Technically the first consideration is the antenna(s) and the Tx/Rx frequency spacing.
The usual frequency spacing is 600khz, and if you want to use a single antenna for Tx and Rx you will need a duplexer with about 80/90dB isolation between transmit and receive ports.
Such duplexers are not simple, lowcost or portable.

You will need separate transmitter and receiver.
The receiver will need good overall screening and good filtering in the RF stages.
The transmitter will need good overall screening and low phase noise to prevent swamping the receiver.

Depending on the application, you will need some control logic and a callsign generator, there are various designs around on the web.


Jim GM3ZMA
 
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thanks for the advise maybe i lacked some details about the project,this are some of the details i am planning to use 2 portabe handies the very dependable icom 02 series and separate antennas for rx and tx to eleminate the high cost of duplexers and proposed frqs.are rx will be at 14meg tx at 15meg or shall i say 146.55 rx 156.55 tx
 
proposed frqs.are rx will be at 14meg tx at 15meg or shall i say 146.55 rx 156.55 tx

156.55Mhz, you have to be joking!

That is marine band channel 11, somewhat outside the amateur frequency allocations!

JimB
 
in your country maybe that is marine band but here in the philippines is not, although i am aware of the allocated amateur freq. which is 144 to 147.00 only,and if i have mentioned 156.55 that is for the purpose of testing only if anybody can help me build a portable repeater
 
The controller can easily and inexpensively be built around a Picaxe chip, a few audio isolation transformers between the RX and TX radio, even a 'roger beep' at the end of the TX... heck, even a simple CW IDer every 9.5 minutes (just to be safe). All this can be done for less than $50USD Im sure of it.

However, since the TX and RX freq difference is typically only a few kc's off, the duplexer is going to be quite expensive!

You can get a VHF duplexer with 1mhz seperation for $60USD on ebay... However a used 2m duplexer will be around $500USD.

Look to Google for more info on the Picaxe and repeater controller...
picaxe repeater controller - Google Search


GL OM,
Andrew
 
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