I have been asked a lot about the rig so I will send this out to the Group.
http://www.qsl.net/wa5bxo/pkd-bxo/rebuild.html http://wa5bxo.shacknet.nu/HAMPICTURES/Pictures/Ham%20Radio/BIG_Rig.JPG http://wa5bxo.shacknet.nu/HAMPICTURES/Pictures/Ham%20Radio/Mic.jpg Movies and audio below provided below by W5OMR http://wa5bxo.shacknet.nu/HAMPICTURES/wa5bxo-on-the-air.wmv http://wa5bxo.shacknet.nu/HAMPICTURES/this%20is%20how%20we%20tune.wmv Your Welcome Herb The main AM rig is spread out into two rooms. It is mostly home brew and a lot of modifications. Even the scope is homebrew. The XMTR room that holds the 6FT rack cabinet is adjacent to the operations console. The 6Ft rack now holds the final amplifier which is a home brewed class C push pull pair of 250ths with link coupling input and output. Just below the Final chassis is the high level modulator chassis which is four 813s in push pull parallel class AB1. The power supplies for these are built in the back side and bottom of the rack cabinet. The modulator supply is 2500 Volts with its own plate XFMR and filters. The final supply is a separate supply with its own plate XFMR and filters but the primary of the plate XFMR for it is passing through a Variac, so that I can adjust the plate supply voltage on the final amp. I generally run about 1600 volts and some where between 300 to 400 milliamps of plate current. In the operations console of the other room is the HQ-145 RCVR and various other pieces of equipment. Most of the Equipment can be patched around in such a way that any of it can be used for carrier excitation to the AM big rig in the other room. Each piece can be operated in stand alone also. When on AM at 3885mhz, this is this is the general setup. The carrier generation begins with a modified TS820 putting out a carrier at about 10-20 watts. This goes into a Heath kit modified SB200 amplifier that brings this up to a 75 watt carrier. This then drives the big rig (PP 250ths) which puts out about 350 watts of carrier. The audio chain begins with a home brewed microphone built into and old Shure dynamic microphone housing. You may notice the 4 red LEDs inside the microphone. The output of the microphone feeds a Shure mixer with auto output leveling. The mixer feeds the main speech amplifier which is a much modified Bogen PA amplifier. The Bogen PA amp feeds the grids of the big modulator in the other room. The big modulator with the four 813s is capable of 1200 watts of audio but now days we only need about 200 watt from it so it sort of loafs along. The out put of the big modulator is feed to a 40 HENRY choke which K4KYV and I sort of built from 2 chokes, in series with the plate supply to final Class C carrier amplifier so that the audio can be imposed on the 1600 volt DC that is feeding the plate circuit of the 250th's. There is enough audio reserve to over modulate by 300 percent so you see the need for the Shure auto output leveling mixer. The out put of the big rig is feed into a home brewed balanced tuner that is mounted on the wall above the operations console. The 600 ohm balanced feed line from the antenna comes through a small Plexiglas window in the wall behind the tuner. The antenna and balanced feed line is made from number 12 wire. There is about 120 feet of the balanced feed line going up to the center of the dipole antenna which is just less than 100 ft high. There is about 125 ft of wire making up each leg of the antenna for a total antenna length of 250 ft. The ends of the ant are about 70 ft high. This type of setup is not your every day rig but is an accumulation of stuff over many years and my good friend BJ and I make it continue to evolve. Good Luck John WA5BXO -----Original Message----- From: Herb Raemsch [mailto:[EMAIL PROTECTED] Sent: Sunday, July 31, 2005 2:34 PM To: [EMAIL PROTECTED] Subject: Speaker Suggestions Hello John Thank You very much for the suggestions on the speaker. Appreciate it very much. Boy that is anice looking transmitter pictured on QRZ web-site. Was wandering what make and model. Anyways I appreciate your input very much. I have been on SSB to long and have forgotten a lot. At 64 am going back to CW and AM so its guys like you I lean toward for a little help. Thank You Herb WA3HGT
