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Re: [Amps] QRO 2500DX MARK lll 4CX800

To: "'Jim Thomson'" <>
Subject: Re: [Amps] QRO 2500DX MARK lll 4CX800
From: "Peter Voelpel" <>
Date: Thu, 4 Apr 2019 20:21:46 +0200
List-post: <>
All Apache Labs transceivers with dual receivers provide pure signal
capability as well as the Hermes SDR and Red Pitaya SDRs.
ADAT ADT-200 does it as well as few others.

You can´t get -59dB IMD-3 two tone test from a 3CX3000F7 at 8KW PEP output
which you will never reach with 100W drive power.
A 8910 tetrode with 200 ohms at the grid without neutralisation does 12KW
out with 100W of drive.


-----Original Message-----
From: Amps [] On Behalf Of Jim Thomson

##  The only modern  SDR  xcvr   for sale on the market right now, 
with...Pure signal... is the  ANAN   7000  + 8000  xcvrs,
which,imo, are not ready for prime time.  Esp judging by the  37 K postings 
of various issues..on their yahoo group, that I belong to.
Pure signal will really take ahold when  Icom, Yaesu, Kenwood   start using 
it in their future products.

##  Heres  my take on tubes Leigh.   Why mess  with a tetrode in the  1st 
place ?    Tetrodes offer  ZERO
advantages  over a   high mu  GG triode.   Heck, you dont require a socket 
on  some  triodes,  nor regulated screen  supplies,  regulated
bias supplies, screen and  anode current protection,  +  compensation on the

input for stray  tube C,  + neutralization etc, etc.

##  A  dead simple,  single chinese  8877   GG  triode amp makes more sense.

2 x  3-500Z is also dead simple..and instant on, no grid current
protection required..perhaps a simple  fast  3agc  grid fuse  at most.

##  From a HB perspective, why bother with a complicated  mess, like the typ

tetrode ?   A  simple  3CX-3000F7 requires no socket,  instant on,
rebuildable,  5-8 kw pep out..or  CCS cxr,  and  -59db  IMD-3.   Most hams 
will die before the tube  does.   Moot point, cuz your kids can have it 
use it..then  pass it on to their kids.

Jim   VE7RF 

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