performance, which would be case if the usual amateur practice of providing gain
control by varying the bias on G2 of the FET was followed.
After the attenuator, a property designed bandpass filter provides very
substantial rejection of out-of-bands signal.
The preamplifier is designed and tested to very high standards. A platted throw
hole epoxy fiberglass pcb is employed, and bushed mounting are provided for
mounting in the FT290.
INSTALATION
Before attempting installation of the SLNA 145sb it is very strongly recommended
that the manual and circuit diagrams supplied by Yaesu/Sommerkamp are
studied thoroughly. If you are at all unsure of your abilities muTek strongly
recommends that you find a competent technician to perform the installation: we
can not accept responsibility for any damage however caused.
If any difficulties are encountered than please get in touch with muTek – we want
to make sure that you are happy
The preamplifier mount on the lugs provided for mounting for optional tone
encode / tone squelch assembly. With the bottom of the unit removed, those may
be found close to the “switch B” unit (see mage 33 of the manual).
1. Remove both top and bottom cover of the transceiver.
2. Remove battery compartment (4 screws).
3. Locate and remove C101. This (normally 470pF or 1nF) capacitor is
located on the main pcb near the PA compartment close to the back panel
of the transceiver. This is probably best done by crushing the component
with a pair a long-noised pliers and cutting clear remaining debris – it may
sound crude, but it’s better than wrecking the reverse side of board –
easily done!
4. Locate and remove L02 – this is usually yellow sleeved toroidally wound
inductor going between the stand-off in the PA compartment and the
adjacent tag-strip. Keep this component – in the unlikely event of the
SLNA 145sb having to be returned for service, the FT290 can fairly easily
be returned to its unmodified state if the removed components are
retained (almost any sub-min plate ceramic capacitor of around 1nF would
be suitable for the C101 in this eventuality).
5. Remove telescopic antenna.
6. Remove the anodized aluminum stripes from each side of the transceiver
case.
7. Unwrap the SLNA 145sb and the kit of cables. Refer to the diagram below
and solder the cables to the preamplifier as shown. BE VERY CAREFULY
NOT to allow small whiskers of the braid for example to short across pins.
