|
From: | Matt Ettus |
Subject: | Re: [Discuss-gnuradio] RFX900 Failure |
Date: | Wed, 24 Feb 2010 15:57:13 -0800 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 |
On 02/24/2010 09:42 AM, David Evans wrote:
Hi all, Power output has significantly dropped, initially by 8dB, now much more. My first thoughts are that the PA has failed, so is it possible to break the transmitter... - by prolonged transmitting at high power (i.e. setting it to/near maximum)? - using a mismatched antenna? - mismatching resulting in VSWR effects? (err, without a load)? I'm obviously going to have to test now, where to start, any suggestions, like what voltage swing before and after the 3315 should I expect?
I have seen this once before with someone who was transmitting at max power continuously. The problem may be in the SAW filter, which would make it easy to fix. You can just put a cap of anywhere between 50 and 1000 pF, size 0603 in the empty capacitor location which is in parallel with the filter.
In order to tell if that really is the problem, you would probably need to probe with an RF probe for your spectrum analyzer or vary fast oscilloscope. You could probe at the antenna port and immediately before the SAW filter, and if there is a big loss in the filter you know that is bad.
If you don't have the equipment to test this, it may be easier to just put the cap in there and try it.
Matt
[Prev in Thread] | Current Thread | [Next in Thread] |