[Premium-Rx] Ten-Tec RX-340 ??

Sun Sep 4 08:14:04 EDT 2005

correction below
  -----Original Message-----
  From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of AC7ZG
  Sent: Sunday, September 04, 2005 5:12 AM
  To: Clemens Paul
  Cc: premium-rx at ml.skirrow.org
  Subject: RE: [Premium-Rx] Ten-Tec RX-340 ??

  Clemens

  I never mentioned the preamp. (which you can also turn on in the ProXX for
MW by the way), And I was specificially talking about weak signal recovery
in the Medium wave spectrum....

  What I talk about is both obvious from usage (where the real receiver will
shine or not)

  and from the specs of the 7800:
  Sensitivity of 7800 (from specs):
    SSB,CW,RTTY(BW 2.4kHz  10dB S/N):
        0.100-1.798MHz  0.5uv (w/preamp 1 ON)
        1.8-29.99MHz      0.16uV(w/preamp 1 ON)
   AM (BW 6kHz, 10d/B S/N):
       0.1-1.799MHz  6.3uV(preamp 1 ON)
       1.8-29.99MHz  2uV(preamp 1 ON)

  This is the same ATTENUATOR CIRCUIT (not lack of Preamp on/off) that the
proXX suffers from.

  A cursory look at the schematics <look in your ICOM7800 looseleaf manual
in section at end, #2 schematic> shows that in the BPF Unit1, there is a
resistor pair at the input of the "B0A" enabled bandpass filter that isn't
duplicated at the input of the other bandpass filters. The R1 value of 47K
from input to ground plus the R3 of "0 ohms" is an attenuation pad circuit.
Like the Pro2/3, you'll have to remove the resistors and jumper R3(maybe not
if it's just a wire jumper across the location already at "0" ohms ) while
leaving R1 "open"  in order to remove the attenuator and restore the Medium
wave sensitivity. HOWEVER, likely in Europe you'll be overloading the MW
input. This does not happen in the weaker signal region of North America.

  So, Clemens, from both specs and from usage, you cannot have the same
medium wave sensitivity as the higher bands, and 0.5uV sensitivity compares
very poorly with the WJ line (however maybe 0.5uV for MW  is comparable to
your EI? I am not familiar with the specs on the EI you mention).

  best regards
  Don

    -----Original Message-----
    From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of Clemens Paul
    Sent: Sunday, September 04, 2005 1:03 AM
    To: AC7ZG
    Cc: premium-rx at ml.skirrow.org
    Subject: Re: [Premium-Rx] Ten-Tec RX-340 ??

    Don,

    contrary to the IC756proxx the IC-7800 can activate its preamp below 1,7
Mhz.
    This results in a MDS of -123dBm or a noise figute of 17dB.
    This is *very well* (about 10dB) below athmospheric noise on MW/LW
during night.
    So If your other receivers performed really better than the Icom on MW
this isn't definitely
    a sensitivity issue.
    My personal experience with my 7800 and Telefunken E1800,which is even
more sensitive below
    1,7 MHz:
    When receiving extremely weak ham cw signals on 137Khz *during daylight*
(groundwave propagation)
    the E1800 gave a little better readibility due to its better
sensitivity.

    73
    Clemens
      ----- Original Message -----
      From: AC7ZG
      To: Aidehua at aol.com ; premium-rx at ml.skirrow.org
      Sent: Sunday, September 04, 2005 1:26 AM
      Subject: RE: [Premium-Rx] Ten-Tec RX-340 ??

      My icom7800 does not hold a candle to the wj8712p/wj8711a/hf1000a for
TP medium wave dxing, nor weak signal recovery on the shortwave bands.
      I don't usually bring it with me to the coast of Washington for this
reason. Like the ICOM756pro2 and 3, the 7800 has an attenuator in circuit
below 1700kHz to prevent overload by AM stations. Guy Atkins has made some
circuit changes to his pro3 to bring it into play as a weak signal MW
receiver, including removing the attenuation circuit and replacing the
roofing filter with one of the 6kHz versions from the 7800. (I've not
similarly butchered my 7800 :-0

      Don
      AC7ZG

      PS I've used one of my wj8711A's for receive (disabled during
transmit) along with the 7800 to do some very weak signal ham radio qsos --
the 7800 could not keep up...
        -----Original Message-----
        From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of Aidehua at aol.com
        Sent: Saturday, September 03, 2005 1:02 PM
        To: premium-rx at ml.skirrow.org
        Subject: Re: [Premium-Rx] Ten-Tec RX-340 ??

        Gosh, I love this group!!  And here I was, feeling guilty for owning
a retirement's worth of receivers....I have never compared the HF-1000A with
the 340, but have done so with my Icom 7800.  The 7800 is comparable on MW
but the SAM on the WJ does supremely well and gives a fullness the 7800
cannot hold a candle to.

        I also agree the a retored/tweaked R390A (my EAC) really does a
superior job on MW and the Tropical Bands.  For a serious night of DX
listening, I always keep the R390 fired up, especially since it's my last
resort for specific targeting of stations (i.e., Africa on 60m).

        Just wanted to chime in on how refreshing the group is here,
considering not too many hams appreciate this aspect of high end receivers.

        73,
        Ed NI6S

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