[Heathkit] Two Question about SB430 Tune Mode
Glen Zook
[email protected]
Sat, 26 Jul 2003 21:03:03 -0700 (PDT)
You don't have to have the receiver in the CW position
to tune the transmitter! Even if the crystal kit is
not installed in the transmitter (you don't have to
have this if the transmitter is used with the SB-300,
SB-301, or SB-303 receivers) the CW crystal is
supplied with the SB-400 / SB-401.
If the heterodyne crystals are not installed, you do
have to have the frequency control switch in the
"locked" position. This is the lever on the control
right next to the meter. This puts the signals from
the receiver (BFO, LMO, and heterodyne oscillator) to
control the transmitter (actually, the LMO is switched
by another switch).
When the receiver is hooked up to the transmitter the
transmitter will function in any of the modes
including CW and tune no matter what position the
receiver is in. You do have to make sure that the
bandswitchs are in the same position when operating in
the "locked" position. If the crystals are installed
in the transmitter, and the lever switch is placed in
the "unlocked" position, then you can operate the
transmitter on any band no matter which band the
receiver is set to.
Although the transmitter CW BFO crystal is of a
different frequency from the other two BFO
frequencies, the receiver uses the USB crystal for
both upper-sideband and CW even when the optional CW
filter is in place. Even when the transmitter is
"locked" to the receiver, when the mode switch is
placed in either the "tune" or "CW" position the BFO
is no longer controlled from the receiver. When it is
"locked" then the receiver BFO is used for USB and
LSB. But, NOT for tune or CW. This is because the
frequency for tune or CW has to go "through" the
filter and not be above or below the filter (which is
where the unwanted sideband is eliminated).
The cable that is recommended by Heath for the LMO,
BFO, and heterodyne oscillator connections is RG62/U.
These cables are specified as being 24 inches long
(which is just long enough to get from the receiver to
the transmitter when they are sitting "side by side").
RG62/U was chosen not really for its impedance (which
is in the neighborhood of 90 ohms) but for the fact
that is is "low capacity" (has only a fraction of the
capacity of RG58/U).
RG62/U should be used for the three connections that I
listed above (for all 3 receivers SB-300, SB-301, and
SB-303). You can use any convenient length of RG58/U
for the antenna connection and shielded cable for the
remainder of the connections. Those are the types of
cables that I supply on the cable kits that I
manufacture. You can get more information on these
from the zcomco website listed at the end of this
message.
But, again, it doesn't matter what mode the receiver
is in to tune the transmitter. It does matter if you
are transceiving with the receiver and are using SSB.
However, if you are using CW or in the tune position
it doesn't matter. I recommend using the transmitter
LMO ("split") operation when operating on CW. This
allows you to "zero beat" the other station and then
tune the receiver for whatever tone you wish to listen
to.
If the receiver LMO is controlling both the
transmitter and receiver, then you do have to use
either USB or CW (if you have the optional CW filter
installed) to get anywhere near the same frequency.
Otherwise, the transmitted signal will be over 2 KHz
away from the receive frequency if the receiver is
placed in LSB when operating CW. If the transmitter
LMO is controlling the transmitter, then you can zero
beat the other station's signal and use LSB. This can
be "handy" if there is QRM near the desired signal and
you are using the SSB filter. Again, if you have the
optional CW filter installed, then the receiver BFO
crystal is still the same one as used for USB.
If, for some reason, you want to operate using USB on
one unit and LSB on the other, you MUST operate using
the "split" LMO position. This is because the
frequency of the LMO is shifted more than 2 KHz
between USB and LSB. There is an adjustment on all of
the Heath LMOs to get the dial to read the same on
both modes. Heath applies a different voltage "bias"
to the LMO to shift the frequency between USB and LSB.
Glen, K9STH
--- "James M. Walker" <[email protected]> wrote:
As for the usage with the receiver, there is no tune
position on them, the receiver mode switch MUST be in
the CW position if you want to tune the transmitter.
Simple as that. Also make sure the LMO load is in for
stand-alone and patched with 90 ohm coax NOT RG-58/(*).
=====
Glen, K9STH
Web sites
http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco
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