SB-650 display wrong when '303 running with '401

[W6CUX]

The HET signal for 28 Mhz operation is probably too marginal to support both
the -401 and the -650 on 10 meters.

I use a modern version of the SB-650 - the "Almost All Digital Electronics
DSP2" - to display the frequency of my -301/-401 combination. I found that
the LMO and BFO outputs of the SB-301 could easily drive both the -401 and
the DSP2 through a Y-connection but the HET signal could drive neither when
they were paralleled. The solution was a preamp that AADE supplies for this
purpose. I connected the HET signal from the -301 to the   -401 in the
normal way and installed the preamp inside the receiver between the HET
oscillator and a spare jack on the back panel for a separate HET connection
to the DSP2. A plus is that with the right connection to the oscillator, the
WWV frequency is also displayed. Works great.

http://www.aade.com/
http://www.aade.com/preamplifier.html

You could also just not work 10 meters! There's not much there these days
anyway.

73, Stu W6CUX

----- Original Message ----- 
From: "Robert Myers" <rsmyers at ROGERS.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Thursday, July 28, 2005 5:55 AM
Subject: [HEATH-TEMPE] SB-650 display wrong when '303 running with '401


My SB-303, with SB-650 digital display, has a weird problem when working
connected to my SB-401.  The problem only occurs when the SB-401 is powered
on, with the Function switch set to STBY, TRCV, or TRAN (and transmitter not
keyed).  I am running things LOCKED - both frequencies controlled by the
'303.

For a BAND setting of 28.0 on the '303, the '650 does not display the right
frequency (all other BAND settings get the frequency displayed accurately)
--- and the incorrect frequency shown bounces around.

What's even stranger is that on the 28.0 setting, when I move the '401 from
STBY to TRCV then to TRAN, the displayed (wrong) frequency changes --- but
it is still always wrong.  When the '303 is set to any band other than 28.0,
the frequency displayed on the '650 does not vary as the '401 has its
function switch moved from STBY to TRCV or to TRAN - and it is always
correct.

 When I pull out the HET Oscillator cable going to the '401 from the '303
the
problem is 'solved,' the display is always correct.  Obviously, you can't
operate like that (when both using '303's frequency).

Does anyone have any idea what's going on here?  (The LMO, BFO and HFO
signals going to the '650 are the tapped off the same signals going to the
'401 with a 100 Ohm resistor is series as per the manual.)

 Thanks,

--- Rob

VE3JQL

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