Let me clarify a little bit........ I am using the supply to power the Micor repeater as well as a GM300 link transceiver. A few weeks ago I started to notice a slight hum on the link radio's transmitted signal. Now, the hum is so bad, and voltage drop significant, that the GM300's transmit signal is dirty and sounds like a spurious emitter when transmitting. If I disable the main repeater TX (Micor), so as to lessen the load and only have the GM300 transmitting, the hum goes away. Being the GM300 only uses the 13.8v output, I'm guessing the other outputs are ok.
I forgot to mention - When I stopped at the site the other day, I heard the transformer buzzing, which increased in loudness when the repeater was keyed (thus placing a heavier load on the transformer). Possible transformer or resonant circuit capacitor failure? I will be stopping at the site in the morning to investigate further and swap it out with a spare. I'll report back with my findings later tomorrow. Thanks Eric KE2D --- In [email protected], Eric Grabowski <[EMAIL PROTECTED]> wrote: > > While I don't have experience with that particular > power supply, the situation you describe is > symptomatic of filter capacitor failure. > > The capacitor's equivalent series resistance (ESR) > becomes so high that it doesn't filter the ac ripple > anymore. > > You should be able to verify this easily by using a > scope to observe the ac ripple on the dc output under > various load conditions. > > Eric KH6CQ > > --- kk2ed <[EMAIL PROTECTED]> wrote: > > > Good Evening, > > > > I have a Micor 75 station power supply that is > > acting up. When the > > repeater is idle, the voltage output appears clean. > > But as the load > > is increased (ie: power output increased), the > > voltage sags and I > > get an annoying hum on the tx (indicative of AC > > ripple on the dc > > side?). It started out as a barely noticeable hum; > > the past few > > days it has gotten to the point where I just shut > > down the > > repeater's tx. > > > > I haven't had a chance to get to the site to swap it > > out with a > > spare. But I'm curious as to what kind of repair I'm > > in for, and > > others' experience with Micor supplies. > > > > What tends to be the failure and/or cause of the > > above condition? > > > > Pass transistor failure? Filter caps? Ferro-resonant > > circuit (cap)? > > > > Thanks for any input > > Eric > > KE2D > > > > > > > > > > _____________________________________________________________________ _______________ > Never miss a thing. Make Yahoo your home page. > http://www.yahoo.com/r/hs >
