Date: 2 February 1985 From: Headquarters, Indiana Wing/DC To: Azden PCS-300 Owners Subject: Adjustment of PCS-300 PLL One of our members recently experienced a problem with his Azden PCS-300 handheld VHF transceiver. The problem appeared to be a failure to transmit for more than a second or two at the beginning of each transmission. In actuality, the radio was transmitting but the frequency was slowly drifting up to about 151 MHz. After some correspondence with the U.S. distributor of the radio, the following cure was found. The problem is caused by a misalignment of the VCO in the PLL circuit. There are 3 circuit boards in the PCS-300. Of course, the one you want is the most difficult to get at, the one in the middle. To get at the correct board, first you must remove the cover. Then you must remove 4 screws, 2 at the bottom of the radio, underneath the battery pack, and 2 more near the top of the radio between the top circuit board and the heat sink. This will enable you to separate the radio, but the plug-in cable to J101 is quite short and must remain connected for you to make the required measurements. If you will turn the front panel counterclockwise about 1/8 turn, you should be able to get at transformer T104 which is quite close to R137. The top exposed end of R137 is TP103. 1.) Turn power on and connect digital voltmeter to TP103. 2.) Set frequency of radio for 142.000 MHz. 3.) Adjust T104 until voltmeter reads 1.00 volts plus or minus 0.3 volt.  Amsterdam View Our Stats   CLICK FOR A FREE DOMAIN NAMES HTTP://WWW.YOURNAME.TK FOR YOUR OWN WEBSITE IF YOU CLICK HERE AND YOU CAN VOTE FOR OUR FREE WEBSITES IN THE TOP 100 LIST  WANT A TOP RANKING ? USE THE ULTIMATE SOFTWARE SUITE FOR WEB SITE PROMOTION  FreeWebSubmissions Submit Your Site To The Web's Top 50 Search Engines For Free THE ALEXA BANNER, THIS BANNER GIVES THE DALLY STATISTICS OF THIS FREE WEB SITE The World of Free Packet Radio Software Amsterdam The World Of Free Packet Radio Software Amsterdam The Netherlands |