Thought I would take the opportunity to talk about where I am on the project, not that many would be interested but have found that sitting down and writing out where you stand in a project often helps clarify what direction to proceed
and found that others may have insight that may be helpful. Besides, bandwidth is cheap and words are free and my ramblings is the disadvantage to allowing me into your group.
The project so far.
After obtaining the RF-1110B amplifier, RF1310 exciter and all the other assorted goodies like the power supply and performance monitor I have been slowly working on getting the system up and running.
Everything has been installed in a roll around rack with front and back rails, slides and supports. Mechanical issues are never big deal, lots of racks, rails and experience from doing this stuff in broadcasting business. So, all the rack
work, power distribution and grounding were easy.
Next problem, what works and what doesn’t. Sound simple but remember that I never saw one of these things up close before and it’s all a learning process.
Discovered that the exciter had a fault light that would not go out and as long as the fault light was lit the operate control would not latch along with the exciter not doing anything. Thought the exciter was at fault but after learning
a little about the exciter found that if I ran that on the bench by itself in the “generator” mode it worked ok with full output.
Also determined that if I provided external drive to the amplifier and kept pushing the operate command that I was seeing power being developed, four or five hundred watts when being driven by my service monitor.
The next step was to ground the FAULT bus between the exciter and the amplifier and see where that gets me. Doing this allowed me to put the amplifier in operate and seeing a KEY LINE VOLTAGE amber light on the performance monitor and at
first seeing 50 volts being applied to all the amplifiers but after a short period of time the two power supplies muted themselves and now refuse to unmute.
Looked over the two 50 volt supplies and did not see anything wrong and all the other voltages are OK so need to determine what’s holding them in mute.
Looks like there are a couple relevant lines. The Key Line, The Key line Interlock and the Fault line.
The Key Line will go high in operate mode and can see it drop when I key the microphone or use the manual key switch on the front of the amplifier. At this point it looks like the Key Line Interlock is low and that may be the issue keeping
the exciter from coming up and keeping the two fifty volt supplies in mute? And the Fault line that’s being held high and also affecting the exciters operation. Just for fun disconnected the Fault feed on the back of the exciter and forced it low at the exciter
to get the whole mess to go into operate and stay there.
Do have a schematic of the PA cards for the Amplifier and of the controller card but not of the amplifier chassis or the power supplies so that’s an issue.
So now my appeal is to try to locate a copy of the RF-1124 power supply and the RF-1110B amplifier manual or at least the schematics.
Long weekend coming up and hope to get time to get out in the shop and try to get this all working. Also discovered that one of the pre-driver MRF-148 in the driver assembly has shorted gate to drain and popped that out. Don’t have any
information on the driver assembly but have a bad feeling that they work in matched pairs.
Sent out a picture of the front of the rack before, here is a shot of the back and all the interconnections. Also just to confuse things further my RF-1110B is not a standard system but one that was modified to work with an external CNR
splitter, combiner and reject load. But that’s all plumbing so no issues there.
Ray F/KA3EKH