John,
Your approach as always is a good one, and can be made to work out quite well. This extra box will allow about a 6DB increase in power from what a screen modulated 6146 can do. The DX-60 with carrier control can arguably better match up to a linear amplifier, but must of us would agree that carrier control as done on this rig is too much, and annoying to those copying a weak signal that goes into and out of the noise with modulation peaks. Now consider these options: 1.) Modify the DX-60 for non carrier control screen modulation. That should provide about 20 watts carrier with room for + 100% modulation. 2.) Modify the DX-60 for plate modulation. This might require a 6146 bias change for proper class C plate modulation bias. You will also have to deal with modulating the screen grid. The plate tuning capacitor might flash over, and other components may need to be beefed up to handle the higher peak power. Once done, you will have a fine 45-50 watt AM rig that you could be proud of. 3.) Combine option 1 with this: Mate up the modified DX-60 to a linear with 1000 watts of dissipation available (like two 3-500Z's). Now you can easily run 250 watts AM or more (maybe 375) of quality AM. 4.) Use the DX-60 as is (stock), or with an amplifier as you wish. The choice is yours, Jim WD5JKO -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John E. Coleman (ARS WA5BXO) Sent: Thursday, March 16, 2006 9:10 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Amplifier to use with my DX-60 I still say, forget the linear, and use less money to build a plate modulator for the DX60. It will work better, sound better, cost less, and heat the shack up less. As I recall the DX 60 has a 6146 in the final for class C CW and puts out about 40-50 watts of carrier if it were plate modulated it would do at least 200 watts PEP and sound great. There is a number of different ways to do the modulator. A lot of guys just find and old PA and a transformer to match to the final. Some build the modulator output stages only, input XFMR tubes and modulation XFMR. Then they drive it with a small microphone amp. That's more stuff to set around on the desk but it works. There are a lot of self contained 25 and 50 watt modulator circuits around and probably a lot of complete one piece store bought modulators as well. As I recall, EICO had a pretty nice one that was to go with the EICO model 720 but it was used on many different rigs as well as being used as a driver for big modulators. A buddy of mine had an ECIO 720 and built a nice home brewed modulator for it using 1625s in AB1. It sounded real good. I built one similar to it with less power output for my Knight Kit T60. The T60 had the same control carrier AM that the DX60 does. What a difference it made when it was plate modulated. Very little modification is necessary in the DX60 to accommodate the external modulator. John, WA5BXO ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006