[Premium-Rx] WJ8718A i.f. filters

[Bill Beamon]

If you hang a digital receiver like an SDR-IQ on the first IF, you can
tailor the filter width with sharp walls to whatever you want...and have a
number of demodulation choices.
Bill Beamon
KD4FNC
Harris R3268/URR
Micro-Tel PR700B
SDR-IQ

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Les Locklear
Sent: Thursday, June 17, 2010 12:32 PM
To: Massimo Corinaldesi; Premium-Rx at mailman.qth.net
Subject: Re: [Premium-Rx] WJ8718A i.f. filters

Massimo and Group,

The Government, both Military and Civilian Agencies operate on frequencies
that are usually allocated and in the clear. That is one reason they usually
have 3.0 khz ssb filters etc. Most amateur radio tranceivers have far better
if filter shapes from that era. Many general coverage shortwave receivers
also have filters that surpass those used in Government contracts.

Les Locklear
Gulfport, Ms.
Dx'ing since '57
Drake R8B
Hammarlund HQ-150
Hammarlund HQ-180A
Hammarlund SP-600 Re-Engineered by John R. Leary
Ten Tec RX-350



  ----- Original Message ----- 
  From: Massimo Corinaldesi 
  To: Premium-Rx at mailman.qth.net 
  Sent: Thursday, June 17, 2010 9:26 AM
  Subject: [Premium-Rx] WJ8718A i.f. filters


  I read the data sheet of the WJ-8718A hf receiver, and I was surprised 
  to see the shape factors of the i.f. filters are very high.
  I think in the years the 8718A was conceived - I suppose first half of 
  '80 -, the technology allowed i.f. filters having better shape factors.
  Why they did so ?

  That's just a technical curiosity.

  Thanks.

     Massimo Corinaldesi  I0MCF
     Roma
     Italy

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