[amsat-bb] Re: true duplex radios

[Martin]

Hi Jim and others.

For ordinary Repeaters the Rx/Tx in the same band is mandatory. But just 
think of the filtering needed for TX'ing lots og watts just 600kHz away 
from your Rx-frq.
This is also the reason why most repeaters (at least that I know of) 
uses really big cavity-filters.

But for Rx/Tx on the same frequency - Forget it. What would be the 
purpose anyway?

In my terms, a full-duplex radio is a radio that listens on one band, 
whilst transmitting on another.

Regards
OZ1TMM, Martin


Jim Heck wrote:
> Hi All,
> 
>   In my experience, you dont have to listen to the output channal of a repeater,
> while transmitting to its input, ie you dont have to hear your own signals coming
> back through the repeater. BUT you do (ideally) when working through a satellite.
> 
>   Again im my experience, such a radio as Greg has described is called a "half
> duplex" one.
> 
>   The big advantage of using a full duplex radio for satellites is that you can
> check if you are being rebroadcast by the satellite or not, without relying on
> others to tell you. (You can also change the polority of the up link signal, for
> maximium smoke!)
> 
> 73 Jim G3WGM
> 
>> -----Original Message-----
>> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org]On
>> Behalf Of Greg D.
>> Sent: 02 June 2009 07:12
>> To: clintbrad4d at earthlink.net; amsat-bb at amsat.org
>> Subject: [amsat-bb] Re: true duplex radios
>>
>>
>>
>> {queue thunder clap}
>>
>> Wait a minute...  How can a radio be capable of cross-band repeat and not
>> be full duplex?  I believe the answer is no.  Cross-band (analog)
>> repeating is inherently full duplex.  So, perhaps this is a simple way to
>> ask a non-satellite person, without having to explain what duplex means.
>>
>> By the way, my Alinco DR-610 mobile rig is also full-duplex.  You may add
>> it to the list.  (In fact, it's got some down-right-weird modes, between
>> the two sides of the radio, that it's sometimes anyone's guess what will
>> happen when you key up.)
>>
>> Greg  KO6TH
>>
>>> From: clintbrad4d at earthlink.net
>>> To: amsat-bb at amsat.org
>>> Date: Mon, 1 Jun 2009 12:37:16 -0700
>>> Subject: [amsat-bb] Re: true duplex radios
>>>
>>>  >> ... Yaesu FT-8800 ...
>>>
>>> Really? Dual-receive, indeed. And will perform crossband repeating.
>>> But I can transmit on one band and simultaneously hear myself on
>>> another with a FT-8800?
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