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[Amps] FW: Transformer Question

To: <>
Subject: [Amps] FW: Transformer Question
From: "Matt" <>
Date: Thu, 27 Feb 2020 09:34:00 -0600
List-post: <>
On the Gonset, the line filter choke is on the low voltage DC return side of 
the diode bridge, I assume to reduce 60Hz ripple.    It is undamaged.   Are you 
referring to this choke for removal?    The 811H schematic shows L7 (which I 
don't see defined in the parts list) on the HV DC supply leading to the RF 
plate choke tagged L4.    I assume L7 in the 811H design serves the same 
purpose but places the choke on the HV side instead of the LV side.

Regarding the 1.4 x transformer voltage...   I am puzzled by this too, and I 
assume the replacement transformer specs for both are listed as peak-to-peak, 
and not RMS, since the literature for both amps indicates the full load plate 
voltage as 1500 VDC.   I guess I could at least call Peter Dahl and ask them to 
confirm this.    I'm not sure if I could get anyone at MFJ who would know.... 


-----Original Message-----
From: Colin Lamb [] 
Sent: Thursday, February 27, 2020 8:44 AM
To: Matt <>;
Subject: Re: [Amps] Transformer Question

The GSB-201 only uses 20uf.  The capacitors are in series so the capacitance is 
divided by 5.  The replacement choke is good.  Throw the choke away.  With a 
capacitor input, you will have 1.4 x the transformer value.  So you will have 
the same value as the other amplifier.  But, one thing you will need higher 
tuning capacitor voltage to stand the voltage increase.  

So, you would want a transformer about 1250 volts x 1.414.  That will give you 
the same voltage as a choke input.  To make up for the choke, you will have to 
use bigger filter caps.  

Maybe you should read a little more about capacitor input power supplies before 
buying one.  

73,  K7FM

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