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Post by raider on Aug 8, 2008 0:00:48 GMT -5
This radio calls for a siltronix 90 vfo which i have. I have no idea how to hook this up to the vfo. There is a jack on the back that seems stock that says tape rec. Any ideas on how to hook this up or what the jack means. PUlling my hair out. I would really appreciate some help. thanks
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Post by Tombstone (R.I.P.) on Aug 8, 2008 7:06:22 GMT -5
The jack is for recording on the air, You'll have to pull a mixer crystal that matches the output of the VFO and connect where the crystal was.
Tombstone
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Post by 2600 on Aug 9, 2008 14:00:00 GMT -5
On the back of the Siltronix VFO you should see a large, single digit that looks like it was applied with a worn-out rubber stamp.
This digit will tell you which version of the VFO you have.
The way you install a slider in a crystal-controlled 32-channel radio is to remove one crystal and connect a shielded wire to that socket. Or, if the crystal is soldered in, the end of the tiny coax gets soldered in place.
All the various external "sliders" were built in multiple versions. Since there were literally dozens of different frequency schemes used for the crystals in 23-channel radios, you had to have a slider that produced an output frequency that matches the crystal.
Needless to say, there are LOTS more 'wrong' combinations of radio and slider than there are 'working' combinations.
I have only a diagram for the 13-880B. If yours does not have the suffix letter "B" following the model number, it could have different crystal frquencies from the ones shown in Sams "CB" series volume 39. If your radio has the same crystals as the "B" version, you need a Siltronix 90 type "1" to match this radio.
A typical installation uses a length of shielded cable with a 'phono'-type plug on one end, to match the socket on the rear of the Siltronix. The channel 1,2,3 and 4 crystal gets pulled out.
The center wire goes to the 'hot' side of the circuit where the old crystal was soldered. The shield side of the cable goes to a grounded foil on the pc board near the crystal.
This radio does not switch the "hot" side of each crystal. It selects the ground side of each crystal to change channels.
Trouble is, the center wire of your slider cable will not get switched "OFF" when you select a different channel on the radio. As a result, you slider cable is now connected all the time. This will throw the remaining channel crystals off frequency, even if you unplug the slider.
This radio becomes a "slider-ONLY" radio once you hook up the Siltronix.
Other models and brands that selected the 'hot' side of the crystal on the channel selector do not have this odd problem.
73
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