Re: [Discuss-gnuradio] power amplifiers on TX

[Martin Braun]

Daniel,

can you please group the pages into something cohesive? Not sure if the
common theme is 'ham radio' or 'hardware', but something like that.

Thanks for adding all the content!

Cheers,
Martin

On 01/10/2016 12:25 PM, Daniel Pocock wrote:
> 
> 
> On 30/12/15 22:24, Marcus Müller wrote:
>> Hi Daniel,
>> Cannot stress this enough:
>> Don't try to do everything to the max right from the start. Sure, 100mW
>> is a lot less than what can do in the licensed bands, but then again,
>> not coming from an amateur background, 120W right out scare me. Please
>> make sure no more than -15dBm are fed into the USRP RX. So at an output
>> power of 120 W ~= 51dBm, you need isolation of at least 66dB between
>> your TX antenna and the RX port of your USRP for the TX frequency. Also,
>> considering you're buying a device that can potentially cover 70MHz to
>> 6GHz, spending lots of money on a powerful amplifier that can but
>> operate on a few MHz really sounds like an unbalanced investment. Maybe
>> reduce the output power (unless you want to do moon bounce, maybe), and
>> get separate filters, just to keep the option of not operating in
>> 144-147MHz; your whole operational range is much smaller than the amount
>> of spectrum you can control with the USRP at once.
>>
>> Of you're not going to use two highly directive antennas for RX and TX
>> to achieve isolation:
>> You will either need an RX/TX switch (that you should definitely control
>> using the USRPs GPIO pins, which can be programmed to certain states
>> when transmitting, receiving or doing full duplex) to isolate RX from TX
>> when transmitting, or an extremely expensive circulator-based device.
>>
> 
> 
> As this isn't specific to ham radio, I created a dedicated page about
> transceivers on the wiki, including some of your feedback:
> 
> https://gnuradio.org/redmine/projects/gnuradio/wiki/HardwareTransceiver
> 
> Can anybody else add more specific examples of RX/TX switches they have
> used, cases and heatsinks for putting everything together, etc?
> 
> 
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