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Tuesday, March 26, 2013

The Heat is On

We have seen a lot of heat in TX7 the past two days.  We were a bit concerned when a hole was burned into a circuit board of the TIGRE.  The TIGRE is not a tiger; it's a major part of the control system for the transmitter.  We had been having trouble with it for several weeks.  Once we smoked the board, we had to remove the unit and repair connections that had been severed.  Once we put the whole thing back together, we were relieved that the TIGRE was back to the way it had been operating.

Then two other problems got our attention.  One power supply failed.  It was replaced with a spare unit.  Then we worked on the original data link problem that had plagued us for weeks.  We finally figured out that the circuit board shown to the left was defective.  We replaced this one with a good spare board.  The data link went away!  TX7 was then able to respond to operator command.

We turned on the cooling system and found that we had some faults to clear.  It took some climbing and poking various connections to get those problems worked out.  We could not proceed to the next stage without those faults being cleared.

The next stage was to get heating to work.  The power amplifier (PA) tube had been simmering in the preheating stage for weeks.  Now it was time to get it fully heated.  The transmitter took the command as if it were not a big a deal.  It was definitely a big deal when we saw this display with no faults related to this stage!  Now we can heat the tube as part of its break-in period before the transmitter puts out an RF signal.

Now we can work on the RF section.  We need to check out the RF driver and then the PA.  We need the antenna connected for the PA test, so worked out well that the RF duct is now done.

Tuesday, March 19, 2013

Duct Dynasty

It's done.  And the focal point of this final phase of the duct is the window.  This powerful connection links the 250KW transmitter to the 4x4 curtain antenna.

The RF signal goes from the transmitter through this long RF output that includes a large filter and balun. 

This is like a take off point.  We could say the HF signal has left the building and is at lift off to the antenna.  From there it is up to the far reaches of the ionosphere 300 kilometers or about 186 miles up to where it starts it's bounce to ... you.`    

And... on the other side of the RF output the work on the transmitter is in process.  Testing and transmitter work are underway looking forward to it's inaugural transmission.  Light her up!