This is likely your problem, there is a 620 ohm resistor in the Mic hi line of the GE MASTR-II PLL exciter connecting the audio line to +10V to provide microphone bias voltage. Unless this resistor is removed +10 will ride down the audio input wire to what ever is connected. Problem is you may be charging a capacitor backwards. With the tantalum caps the NHRC series use and the mean voltage is 1/2 Vin (6.9 volts) on the op-amp when no audio modulation occurs, it is possible to dry one out because of charging it backwards. The + lead of the capacitor should be to the side which is most positive, in this case the MASTR-2.
I had the same problem with another controller and my M2PLL, I went to the site and the 1uF tantalum I put in place between controller and radio blew up in my face so it was pretty obvious as to the problem. Feel around for "Hot spots" to find the bad cap. I cut one lead on the bias resistor in the exciter and replaced the cap with a 1uF non-polar ceramic. Jeff Otterson <[EMAIL PROTECTED]> wrote: > >Hi, > My guess is that there is a bad DC blocking cap either in the exciter or >the controller. > > Best advice is to talk to Pete at NHRC, he knows the hardware a lot >better than I do. Those guys say all I do is "typing..." > > Jeff > > >At 04:10 PM 11/25/2004, you wrote: > > >>Jeff, I have a Mastr II station. A NHRC 3+ as the controller and >>your DAD board. In the audio chain I'm also using a GE channel guard >>board. The 3+, DAD board and CG board are in the same enclosure with >>feed thru caps. I have disconnected the receiver and left the Pll >>exciter audio hooked up. When I ground the PTT line no audio comes >>thru except crackling and static, and it comes and goes. The PA is >>not in line, the exciter is running alone into a dummy load. I've >>tapped and wiggled all components and I can not find a spot where I >>can get it to stop or start. I hope I've covered everything. >> >>Happy Thanksgiving to you and the group also....Jim km0k >> >> >> >>--- In Repeater-Builder@yahoogroups.com, Jeff Otterson >><[EMAIL PROTECTED]> wrote: >> > Yes, possibly a bad capacitor anywhere in the audio chain. >> > >> > What else do you have connected up? A receiver? >> > >> > Happy Thanksgiving! >> > >> > Jeff >> > >> > >> > >> > >> > >> > At 11:09 AM 11/25/2004, you wrote: >> > >> > >> > >--- In Repeater-Builder@yahoogroups.com, Jeff Otterson >> > ><[EMAIL PROTECTED]> wrote: >> > >Jeff, I disconnected the audio line to the exciter. NO Noise, so >> > >then I disconnected the audio from the Rx. The noise was still >> > >there. The only thing left is the NRHC 3+ controller. What would >> > >generate noise there, Bad Cap? What should I look for? Tnx...Jim >> > > >> > > >> > > > Bad capacitor in the audio stage? >> > > > >> > > > Jeff >> > > > >> > > > At 09:39 AM 11/25/2004, you wrote: >> > > > >> > > > >> > > > >Hi group! >> > > > >I have a vhf pll exciter that is very noisy, by that I mean >> > >scratchy >> > > > >sounds on the carrier. When I unplug the PA and run the >>exciter >> > > > >alone with no audio into a dummy load I get this noise, so I >>know >> > >it >> > > > >is coming from >> > > > >the exciter. I cleaned all the contacts that the audio and >> > >bandpass >> > > > >boards plug into and also the edge connecter plug, ICOM etc. >> > >Touched >> > > > >all posts with a touch of new solder, but still have it. >> > > > >I even swapped audio and bandpass boards to no avail. So I >> > >replaced >> > > > >it with another exciter, and this one is a >> > > > >lot quieter. What would cause this exciter to generate noise? >>I >> > > > >modified the Band Pass Filter from G2 to a G1 and replaced the >> > > > >aluminum slug with a ferrite one. I would like to fix this >>one if >> > >I >> > > > >can as they are hard to come by. Is there any suggestions >>where I >> > > > >should start looking? Has anyone else had this problem? >>Thanks in >> > > > >advance. >> > > > > >> > > > >Jim KMØK >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > >Yahoo! Groups Links >> > > > > >> > > > > >> > > > > >> > > > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > >Yahoo! Groups Links >> > > >> > > >> > > >> > > >> >> >> >> >> >> >> >> >>Yahoo! Groups Links >> >> >> >> > > > > > > >Yahoo! Groups Links > > > > > > > > __________________________________________________________________ Switch to Netscape Internet Service. As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register Netscape. Just the Net You Need. New! Netscape Toolbar for Internet Explorer Search from anywhere on the Web and block those annoying pop-ups. Download now at http://channels.netscape.com/ns/search/install.jsp Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
