[Amps] QRO 2500DX MARK lll 4CX800

[Jim Thomson]

##  The only xcvrs  Apache labs are currently selling is the  100w 
7000..and the  200w  8000.
They require an outboard   HD  13.8 vdc supply.   They only come with an 
internal  13.8  to 50 vdc
supply.   Plus they require a stand alone gaming PC, etc.  IMO, the build 
quality on the 7000  +
8000 is not quite up to standard...yet.  Still a bunch of mickey mouse 
issues that have to be dealt with.

##   The  3CX-3000F7  will achieve its -59db  IMD-3  with  200 w of drive at 
aprx  5.5 kw pep out.
Its a moot point anyway.   Use  PS and  TX with  -70db  IMD... and all that 
happens is stations on either side of
you can now get closer to your  freq.  They dont hear you.... but you hear 
them.     If everyone used it, I estimate you
could  almost double the number of stations   on a given band.   It will 
take years to fully implement the concept.

##  The 8910 is a good tube.... but  you forgot to mention it idles at 9.375 
kw.... which is a bunch.   -47db pep for
IMD3  +  IMD5   is superb for that power level.   Toss in PS to the mix, 
then it becomes   -70 db  for  IMD3  and above.
Which is outstanding.... just  whats required for folks with big ants..and 
loads of power.   Then you can also reduce
the idle power of the tube... and still maintain  -70db imd3+ ...then the 
whole thing comes together.

Jim   VE7RF

-----Original Message----- 
From: Peter Voelpel
Sent: Thursday, April 4, 2019 11:21 AM
To: 'Jim Thomson'
Cc: amps at contesting.com
Subject: RE: [Amps] QRO 2500DX MARK lll 4CX800

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.

73
Peter



-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] 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
rebuilt,
use it..then  pass it on to their kids.

Jim   VE7RF

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