Hi all, I just found the problem with this transmitter, problem described below. To force F1 at all times on the exciter, I jumped from the channel element pin to Switched A-. NOT a good idea. Doing that apparently creates a ground loop and an oscillation at around 50kc. It did this with two different exciters. Moving the ground to A- completely fixed the problem.
This was driving me NUTS. There probably is a proper place to force F1, but for now I'll leave it on A-. It keeps the channel element active all the time, which is annoying during bench work while monitoring on-channel. Laryn K8TVZ --- In [email protected], "Laryn Lohman" <[EMAIL PROTECTED]> wrote: > > Hi all, I have a base station that came with a TLE1703 amp. It was a > part of Medcom equipment at a local hospital. I took it out of > storage last week, and it keyed up fine, with about 40 watts out. I > also have a TLE1713 amp from another station, and after quickly > swapping it with the 1703, it too seemed fine with about 70 watts out. > > After moving things around in the cabinet last nite, and having the > 1713 amp installed, I noticed an arcing noise from the amp. Keying > the amp with the cover off revealed arcing at random places near the > negative DC bus, and the 4.7uf capacitors getting very hot. Since > this amp shows evidence of being serviced at some point, I decided to > move back to the original 1703 amp. This amp is very clean inside and > shows no evidence of ever being serviced. This amp too will arc with > the capacitors getting very hot after only a few seconds of keydown. > > So what could be the problem. I am using a good wattmeter and load. > Is there something in the antenna network after the amp that could be > bad? I measured the SWR looking into the antenna network with the > load on the other end and it shows 2.1:1. Isn't that a little high?? > Or maybe the caps are simply old and dried out? > > Where do I look for the problem? > > Laryn K8TVZ >
