[TowerTalk] 1dB more RF Power?

[Jim Thomson]

From: Jim Brown <jim at audiosystemsgroup.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] 1dB more RF Power?

On 5/7/2020 10:15 AM, Jim Thomson wrote:
> Hundreds  of  tests  have  been  run,  with ssb  signals  right  at the  noise  level,
> or  slightly  above  the  noise  level.  And  in  every  case,  increasing the  top  end
> improves  speech intelligibility  by  a HUGE  amount.

<Of course. And in speech reinforcement systems, we carry response up to 
<at least 10 kHz. BUT my advice is for weak signal communications 
<circuits for DXing and contesting. Band congestion is extreme during 
<both of these conditions, so the use of ESSB is out of the question for 
<these times.

> Microphone is a RE-27.

<That's a fine microphone. I own several, also RE20s, which I use for 
<recording music. They are my first choice for trombone, and for tenor 
<and baritone saxophones. It is massive overkill for ham radio, and it's 
<a relatively flat mic, so it lacks the built-in boost around 3 kHz that 
<good communications mics provide.

<73, Jim K9YC

##  forget contesting.  But  for  dx  use, essb  works  superb  into  EU/south  pacific/
SA/JA and  everywhere else..all  bands  too,  including  80m.   ESSB  usually  takes place where
congestion  /qrm  is not present, or  BW  minimized  to  deal  with  it.  IE:  4  khz  vs  5  khz. 

##  Check the  response  curve on a RE-27..its  not flat,  it  rises.    RE-27 has  2 x built  in bass  roll  off  freqs.
2nd  one  rolls  off  below  1 khz.   With  2nd  filter  on,
the  response  almost  looks sorta  like a pre emphasis  curve.  Moot  point,
since  I  EQ it  for  my  tastes..and  dont  normally use  either filter. An  ideal,  optimized  EQ  setup only works for
one  mic  and  one  operator.   Local  buddy jumps into  my chair, and  eq is  all wrong for
his  voice....and  vice  versa  when  I  visit  his  station 1  mile  away. 

##  Local  ham  buddy,  his  bro in law  runs a  recording studio  across  town.  A  myriad
of  condenser  mics and  avalon  pre-amps,  daws etc,  etc.  He  uses the  RE-20  for  saxaphone,
its  superb.

##  I  have  had  minimal  to  zero  success  with...  communication  microphones.   I  and  others  can  hear  the
distortion  in them  asap,  vs a RE-20,  RE-27, MD-421, SM-7,  various  popular  condenser mics  etc.  Its  like
a  layer of..gunge.  Apparently its  the IM  distortion  from  the  lower  quality  mics.  Its  not  some  subtle  difference
either,  its  blatantly  obvious...apples  and  oranges.

##  To  pull  all this  off,  I  cant  use the  junk  mic  pre-amp  on  my  yaesus.   Audio  is  fed  directly..via  a 20  db  pad, then jensen  xfmr
into the analog  BM..via a 220  uf,  non  polarized,  panasonic coupling  cap.  Bill whitlock  was  adamant
about that at the  time.  With  no  coupling cap  installed, the  BM  is  instantly  unbalanced,  resulting  in  CXR  present.
Output  of  cap  is  wired  directly to the  correct  pin on the  analog  BM  chip.   Audio  comes in the rear  on a new chassis
mounted  rca  connector.....  so no pin  1 issues.

##  similar  deal  on  RX.  Output of analog  product  detector  is  routed to  yet  another newly  installed  RCA  chassis  connector,
where  it  is  amplified  externally...  (  2nd  channel of  my rack mount mic pre-amp)..then  into a class  A  headphone  amp  setup.
If  driving speakers,  its  fed into the turntable input  on  my  external   stereo pre-amp.   But the  RIAA  circuit is  1st  removed,so 
no  de-emphasis   takes  place.    Yaesu   1.5  watt  audio  amp and headphone  amp is junk,  we  cant  use  it.   Headphones  are
either  sennheiser   HD-250s,  or sometimes the  boom-mic  version..,.or  sennheiser HD-650s.   Thats about  as good as  I can  get it.
The  650s  are  superb, they  let  your  ears  breathe.   The  250s  seal  out  noise,  but are  like  wearing  ear muffs. 

##  Does  your elecraft  K3    rx  or  tx  beyond 3 khz ??   If not on  RX,  you have  no  way
to  evaluate the mode.  2.4  khz  audio  is  fatiguing,  I  dont  miss it.   I  dont  miss  not  having to  use phonetics  either.

Jim  VE7RF