A Poor Mechanical Design
I turned on my FT 1000MP Mark V IF rig early Saturday Morning to start the 10 GHz contest and was greeted with no received signals on any band 50 MHz through 24 GHz, and no transmit power on any band. I substituted an Elecraft K2 for the FT1000MP and I had good receive and transmit function.
The FT-1000 MP rattled suspiciously as I carried it from the operating desk over to the workbench. I opened it up, and lots of rat pellets spilled out!
There were more pellets inside!
This picture shows where 9 wires were gnawed or cut in half. The mice must have been hungry!
This is how the two cables [one with 6 wires, one with 3 wires] looked after I disconnected them from the circuit boards and removed them from the radio.
The wires were repaired and put back into the FT 1000MP. Unfortunately, even with the repaired cables neither the main receiver or the transmitter worked, although the sub-receiver did work. A review of the FT 1000 MP circuitry indicated that this meant that the problem was likely related to the IF board. When that board was supplied with an RF signal at 70.455 MHz [the 1st IF frequency], the FT 1000MP produced a loud signal in the speaker, indicating that the IF board itself was likely OK. Checking further, I found that the 2nd LO [62.24 MHz] was OK. The 3rd LO [8.67 MHz] was OK. But there was no signal output from the 1st LO [70.555-100.455 MHz]. If I supplied a first LO signal with my HP8640 at -20 to +10 dBm, the receiver worked. So the first LO was the problem.
Measuring the voltages at J4005 on the Local oscillator board, I found that the +9 volt and +5 volt pins had the proper voltages, but the +13 volt pin had only +0.24 volts. I applied +13 volts to this pin and the 1st LO signal appeared, and the receiver came to life and functioned normally. But why was there no +13 volts here? Had I made a wrong assumption in wiring the broken cables when I assumed that the designers had consistently connected pin 1 to pin 1, pin 2 to pin 2, etc?
No, I had not made an error. When I traced the wire going to the +13 V pin on J4005 deep into the FT 1000MP, I found yet another broken wire, along with some more pellets and discoloration of the metal frame of the FT1000MP, indicating that the mouse/mice apparently spent a good deal of time in this place.
I fixed this broken wire and of course I again had +13 V at the appropriate pin on J4005, the 1st LO worked again, and the FT 1000 MP was restored to its previous excellent working condition.
I never liked the mechanical design of the FT 1000MP Mark V, as it is very difficult [for a human] to gain access to some of the circuit boards. But now I know that the design is also poor because it makes it very easy for small rodents to gain access to these same areas. At the top of the unit, at the junction of the rear heatsink with the front top panel, are 4 rectangular openings which measure approximately 1 cm x 1 cm , which is plenty of room for a little mouse to gain entry into the FT 1000 MP Mark V. The NIH website says that a nickel-sized opening is PLENTY of room for these creatures to gain access to anything. See the photo at the top of the page.
From now on, a metal ruler will sit in the slot on the top of the FT 1000 MP Mark V when I am not using it, to block the rodent access portals that permitted this to happen.
Copyright 1997-2007 COPYRIGHT Roger Rehr W3SZ. All Rights Reserved