At 8/27/2008 21:04, you wrote: >On more than one occasion, I have found those holes to be the cause of >leakage, especially at UHF. Sometimes, RF leaks out of orifices that >"conventional wisdom" might refute, but it does happen. A case in point: I >once put a Hamtronics UHF exciter into a Hamtronics "RF-Tight Enclosure" to >use as a stable low-power RF source for a signal coverage survey. Despite >using feed-through filters for the power leads (the Morse ID unit was inside >the case), there was significant RF leakage even when a dummy load was put >directly on the N-Female RF output connector. Even though the Hamtronics >enclosure halves were well fitted, there was a very small gap, perhaps >0.002" where the metal pieces joined. I found that I could press the gap >closed with a finger, and the leakage went away.
Yes, but that gap was in fact a very long slot, plenty long enough to pass RF with impunity. > I had some 3M #1170 >aluminum shielding tape available, so I sealed all of the seams with it. >Voila! I now had a true RF-tight enclosure. Yup, BTDT. >The dimensions of the holes and slots on the sides of the Motorola T-1500 >series duplexer are considerably larger than the tiny apertures noted in my >example above, so it should not be a surprise that some leakage can occur. We're not on the same page then w.r.t. the holes, as I thought you were talking about the slots for the notch adjustment. Looking at one of these cans on my desk right now, the longest slot I see is maybe 1/2 an inch in length. The only seam I can see that would be a problem is the bottom cap, & there are screws every 2 inches plus the cap is fairly tight fitting. Bob NO6B
