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LF: Re: Re: Re: Decca 5501 500

To: <[email protected]>
Subject: LF: Re: Re: Re: Decca 5501 500
From: "Albert" <[email protected]>
Date: Fri, 8 Oct 2010 22:00:43 +0200
In-reply-to: <002b01cb6721$d2406b90$0401a8c0@xphd97xgq27nyf>
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Mal,
 
Thanks info. I only changed the PA L and C values to resonate on 500 kHz. Max output 800 W at 57 V supply.
 
73, Albert  
----- Original Message -----
Sent: Friday, October 08, 2010 9:48 PM
Subject: LF: Re: Re: Decca 5501 500

Albert
I did not use any of the original PA components, just the driver/PA unit.
I have the option of VFO or Xtal ctl to drive the unit and I calculated the values for the PA coil and Caps. I used an  air wound coil and new caps, also a different ferrite matching transformer to match PA fets to 50 ohms.
My HT supply is 60 Volts and the driver voltage regulated 26Volts. One individuial unit is sufficient on 500 Kcs but multiple units can be used with a suitable ratio of windings for the matching transformer to 50 ohms or whatever Z you require.
 My antenna system and test equipment is designed for 50 ohms.  If you have optimum PA L/C values with suitable ferrite 3C5 matching transformer then power output is similar to the original design figures.
 73 de mal/g3kev
 
 
 
----- Original Message -----
From: Albert
Sent: Friday, October 08, 2010 8:15 PM
Subject: LF: Re: Decca 5501 500

Hello Mal,
 
As you know I did the same a couple of years ago. What is your max. output and at what supply voltage ? Did you leave the coupling/output transformer as it was ?
 
73, Albert PA0A    
----- Original Message -----
To: rsgb
Sent: Friday, October 08, 2010 8:52 PM
Subject: LF: Decca 5501 500

MF grp
I have modified a Decca 5501 unit for 500 Kcs and am currently using it on the band and getting good reports.
Circuit details available for anyone interested in converting these units.
73 de mal/g3kev
 
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