For quite awhile, I have been battling a low power problem with an older circa 1995 Down East Microwave 1296-144 transverter. At first I thought the PA was blown, I removed it and installed an outboard PA with no success. Eventually I replaced the entire transmit chain with still no improvement.
Most recently, I replaced the mixer IC. The original mixer chip is no longer made, however a newer model which spec's somewhat better than the original was installed.
I never reinstalled the PA module. I am going to do some testing very soon with the +10dBm output from the driver. If everything checks out, I'll continue to use the outboard 2W module, then feed that into the 30W PA. Keeping the rig this way, in my opinion would be more versatile as far as making improvements and upgrades on the circuit. Because everything is interconnected using UT-141 copper hardline, things such as bandpass filters and amplifier replacements can be more easily tried.
I am hoping to put the rig on a spectrum analyser and power meter to determine if the transverter is working properly. If it is, I plan on operating some 1296 up on the Lake, as well as possibly some mountaintop operations this summer. Stay tuned to my blog, I'll report here on the performance once I am able to make the proper tests.
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Good luck - it sounds like a blown mixer was the culprit. Finding 1296 isolators to protect the mixer isn't all that easy.
ReplyDeleteActually, I think I just overdriven it with IF drive at some point.
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