[Elecraft] 700 Hz roofing filters

[Bill Conkling]

Are you sure that's not "J3E" for AM, Single sideBand, surpressed carrier,
one analoge channel with telephony?

...bc

-----Original Message-----
From: Jeff Cochrane - VK4BOF [mailto:vk4bof.elecraft at gmail.com] 
Sent: Tuesday, September 21, 2010 8:19 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] 700 Hz roofing filters

Hi Joe et al,
I'm going to hazzard a guess here as to why Elecraft dont allow the 13KHz
filter for AM/ESSB TX.

Because it's illegal.
SSB is called mode A3J in most of the legal documents that govern our hobby.
The reason why the mode is called A3J in all the legal stuff is that the 3
is the maximum bandwidth in khz that is permitted.)
Thus, anything more than the 3KHz SSB bandwidth is against the laws that
govern us.

The F.C.C. in the US of A and here in Australia, A.C.M.A. both allow a
maximum of 3KHz for SSB TX bandwidth on any HF band.
So it would be a fair bet then that because the K3 is a FCC type approved
radio that part of that type approval includes that it must not transmit SSB
bandwidths that are wider than permitted.

My $0.02c worth (Plus GST/VAT/Sales Tax as applicable)


Jeff Cochrane - VK4BOF
Innisfail, QLD, Australia
Elecraft K3# 4257

  ----- Original Message ----- 
  From: Joe Subich, W4TV 
  To: elecraft at mailman.qth.net 
  Sent: Wednesday, September 22, 2010 9:44 AM
  Subject: Re: [Elecraft] 700 Hz roofing filters



  In general I agree with Wayne although I prefer to have a more
  narrow bandwidth option for SSB (1.8 or 1.5 KHz).  In order to
  make room for the 1.5/1.8 KHz filter, I deleted the AM filter
  and use only the FM filter for the "low priority" modes wider
  than 2.8 KHz.  However, it continues to frustrate me that
  Elecraft have *STILL* not allowed us to use the 13 KHz filter
  for AM/ESSB transmit (officially).

  In any case, given the measured performance of the INRAD/Elecraft
  "250 Hz" filter (about 350 to 375 Hz), I can certainly see the
  utility of something like:

  FL1   13 kHz (FM/AM/ESSB)
  FL2   2.7 or 2.8 kHz (SSB and casual CW/DATA tuning)
  FL3   1.8 or 1.5 KHz (Narrow SSB and wide data modes)
  FL4   700 Hz (casual/normal CW/DATA)
  FL5   350 Hz (Narrow CW/RTTY in heavy QRM)

  While the "350 Hz" filter would lack the absolute selectivity of
  the Elecraft 200 Hz 5-pole filter, it would be nearly optimum
  for 45.45 baud RTTY and still provide a useful "narrow CW" option.

  73,

      ... Joe, W4TV

  On 9/21/2010 6:07 PM, Wayne Burdick wrote:
  > 700 Hz is a useful CW/DATA filter bandwidth, certainly. I'm not
  > surprised that some K3 owners are interested in this.
  >
  > Personally, I prefer much narrow CW/DATA bandwidths, and I use all
  > modes. The lineup I use (and generally recommend) is:
  >
  > FL1   13 kHz (FM)
  > FL2   6 kHz (AM/ESSB)
  > FL3   2.7 or 2.8 kHz (SSB and casual CW/DATA tuning)
  > FL4   400 or 500 Hz (normal CW/DATA)
  > FL5   200 Hz (CW/DATA in heavy QRM)
  >
  > 73,
  > Wayne
  > N6KR
  >
  >
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