[Amps] 572's

[Jim Thomson]

Date: Thu, 2 May 2013 20:16:43 -0500
From: "kingwood" <k5jv at kingwoodcable.com>
To: "Eddy Swynar" <deswynar at xplornet.ca>, "Amp Reflector"
<amps at contesting.com>
Subject: Re: [Amps] 572's

       
        Think back and remember when you mistakenly plugged a 250TL into a rig, thinking you were plugging in a  250TH.  That difference is what I saw with the last batch of Chinese 572B I had.  If the factory gets the problem corrected, I will continue to use them, as I really do not have a choice, or perhaps, I do.  How about a simple modification to install a single, horizontally mounted, 3CX800A7 in an SB-200, or Yaesu FL-2100?  Filament voltage and cooling should be the only issues of concern.  The existing power supply should provide enough power get around 1,000 watts PEP output.  Then, with W7RY?s vacuum relay QSK system, seems to me, you would be a great little desktop amp.  I have been running a Dentron MLA 2500, modified this way, for about three years (Not the QSK). with absolutely no problems.  My concern with this mod was mounting the tube horizontally.  This has not been an issue, up to this point.  Comments?

73 de Lon, K5JV

Lon W. Cottingham


##  dream on if you think for one minute that you will get 1000 w pep out of any yaesu FL-2100B amp.   The xfmr in that thing runs blazing HOT, just sitting there, with fils on, and in standby. 
The same xfmr also has a 6,3V @ 8A winding built into it.   I have checked several of em, all new, back in the late 70’s.  I sold mine, and bought a Drake L4B.   For the price of a single
3CX-800A7,  you could buy a lot of chinese  572B’s.     Using a 800w CCS  anode diss tube in an amp that’s ready to blow it’s brains out at 625w out is a waste of $ and effort.
572B amps, whether in pairs or  4 at a time are table top toy amps...best relegated to  6m  service.   Use a real amp with a real tube in it. 

Jim   VE7RF .