Doug, Thanks for the story. This next weekend I will go over the inside with a fine tooth comb and see if I can find any cracks or bad solder joints.
My brain is going to but not just from this project. 73 John --- In Repeater-Builder@yahoogroups.com, "Douglas" <dougd...@...> wrote: > > > Let me tell you a little story about this kind of problem. I had a similar > situation on a VHF mastr II repeater where a signal sounded great one time > and noisy the next. The problem turned out to be a hairline crack in a solder > pad that was used to bridge two circuit boards and the output connectors to a > circuit board, within the PA assembly. It would run great power and then low > power from one transmission to the next. The output power would drop > noticably as seen on a relative signal meter on my rig. That was how I > localized it. > > When we would put a meter on the output, it had just enough sstress on the > cable to make a good connection and all was well, hookk it back to the > duplexer, and the intermittant problem returned. > > I suspect that same kind of thing could happen on a receiver connection. > > The only real way to fix is to touch all the solder terminals that are used > for primary signal in the input or output route. > > Good luck. I liked to have lost my brain over that one (what brain is left > from the 60s). > > Doug > > KC0SDQ > > > > --- In Repeater-Builder@yahoogroups.com, "W3ML" <w3ml@> wrote: > > > > Thanks Mark, > > > > I will go read that article. Thought I read them all, since January, trying > > to learn all I can. > > > > That is when I decided to get into this repeater business. It has been a > > great learning experience for sure. > > > > 73 > > John, W3ML > > > > > > > > > > --- In Repeater-Builder@yahoogroups.com, "Mark" <n9wys@> wrote: > > > > > > John, > > > > > > I'll chime in here and agree with Chuck's suggestion to try a little more > > > "fire in the wire"... > > > > > > It sounds as if your PA is less spurious now than before, but you need to > > > dial it up more to eliminate all the spurious products. Solid state PAs, > > > especially mobiles, are noted for this when run at considerably less than > > > rated output. If I remember the beginning of the thread, this was a > > > Mastr-II mobile... > > > > > > Seems as if I remember a rule of thumb that a solid state PA won't be > > > stable > > > beginning around 60-70% of its rated output. If you're at 55W now, > > > another > > > 10-15W won't make much difference in the received signal strength, but > > > will > > > help a LOT to stabilize the PA. > > > > > > This article: http://www.repeater-builder.com/ge/mastrIIgeneral.html says > > > not to run Mastr-II PAs at less than 40%. In your case, you're at about > > > 50% > > > now and still a little spurious, so... crank her up a tad more (to maybe > > > 70W) and see if that clears it all up. ;-) The article also has other > > > suggestions on how to deal with desense. > > > > > > 73, > > > Mark - N9WYS > > > > > > -----Original Message----- > > > From: Repeater-Builder@yahoogroups.com On Behalf Of W3ML > > > > > > I probably will turn it up more to see what happens. When I had it at 5 > > > watts out we had no problems at all. > > > > > > Over the 10 watts is when the noise was really bad. Now at 55 it works > > > and > > > then it doesn't and then it works again. > > > > > > So, yes I still have something wrong and maybe one of these days I will > > > get > > > another grant and convince the club to buy another GE Mastr II and and a > > > new > > > antenna and coax. Maybe that will fix it. > > > > > > People we got radio from are not answering. > > > > > > John > > > > > > > > > --- In Repeater-Builder@yahoogroups.com, "Chuck Kelsey" <wb2edv@> wrote: > > > > > > > > I'd suggest turning the power up more. You have it set at about 50% and > > > the > > > > transmitter may be intermittently spurious at that level. > > > > > > > > Watch the wattmeter when things act up and see if anything changes when > > > you > > > > notice the desense happening. You can also pull the TX ICOM when the > > > problem > > > > is happening and see if the receive clears up on the local speaker. > > > > > > > > There are so many things that could be at fault - loose connector, bad > > > > antenna, problem with transmitter, problem with receiver, intermod > > > > issue, > > > > etc. > > > > > > > > Ask the people you got the radio from if they had the same problem with > > > it. > > > > > > > > Chuck > > > > WB2EDV > > > > > >
