[AMRadio] Amplifier to use with my DX-60


Jim Miller WB5OXQ wb5oxq at grandecom.net
Fri Mar 17 15:21:04 EST 2006


About $100 each new I believe  My Centurion has 2 of them and they have 
lasted over 5 years now.  375 watts of carrier is easy on them.
----- Original Message ----- 
From: "John E. Coleman (ARS WA5BXO)" <wa5bxo2005 at pctechref.com>
To: "'Discussion of AM Radio'" <amradio at mailman.qth.net>
Sent: Friday, March 17, 2006 10:28 AM
Subject: RE: [AMRadio] Amplifier to use with my DX-60


> Yep, there is no doubt that the pair of 3-500Zs and getting rid of
> the control carrier on the DX60 would be better but a lot more expense I
> think. Aren't 3-500Zs pretty expensive?
>
> John
>
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Jim candela
> Sent: Friday, March 17, 2006 10:00 AM
> To: Discussion of AM Radio
> Subject: RE: [AMRadio] Amplifier to use with my DX-60
>
>
>
> 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: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net]On 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
>
>
>
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