SECTION 3 - CONNECTION TO THE TRANSCEIVER
ALPHA 86 interconnections to the station transceiver are shown in fi ures 2 and 3 on pa e 7.
3.1 Coax Types & Connectors
Connect the transceiver RF output to the ALPHA 86 RF input with 50 ohm coaxial cable-type RG-58C/U
or equivalent Coaxial cable used between the ALPHA'S RF output and antenna should be type RG-8A/U,
RG-213/U, or equivalent hi h quality type. Type RG-8X cable is not recommended. Su ested connectors
are Amphenol 83-1SP male UHF type (with reducin fittin type UG-175 for use with RG-58C/U).
32 T/R Switchin
For transmit/receive switchin the ALPHA 86 requires a relay contact closure on transmit across its
RELAY jack (center pin to chassis). This control function is supplied by the transceiver, usually from a
dedicated relay that is normally open in receive and closes in transmit.
The relay contact must close before RF drive is applied. The ALPHA 86 protective circuitry will not
allow the amplifier to "hot switch" with RF drive applied. Attemptin to force a hot switch will cause
protective circuitry to lock out the receive to transmit chan e over. If this happens the "T/R" fault LED will
illuminate. It may be reset by removin drive, unkeyin the transceiver, and switchin the ALPHA from
operate (OPR) to standby (STBY) and back to operate (OPR).
A few (mostly older model) transceivers may enerate an RF transient (spike) when keyed. This spike
may activate the ALPHA 86's excessive rid current protection, in which case modification of the transceiver
will be necessary. For specific instructions contact the ETO customer service department.
Fi ure 2 should be used with late model transceivers such as those listed below, and will allow the full
capabilities of the ALPHA 86 includin break-in (QSK) operation, to be enjoyed. Suitable transceivers
include at least these (as of 9/90):
*
Kenwood TS-9405, TS-950S/D, TS440S, and later production versions of the TS-930S and TS-4305
Icom IC-735, IC-751, IC-751 A, IC-761, IC-765, and IC-781
Yaesu FT-757, FT-767, FT-1, and FT-1000
Fi ure 3 shows a switchin arran ement that may be used to facilitate chan in from conventional SSB/
VOX or PTT to CW break-in operation with older transceivers that have inappropriate T/R sequencin . The
desired mode of operation is selected by the external DPDT switch. QSK-capable transmitters of older desi n
may also require connection per Fi ure 3.
For transceivers or transmitters not mentioned above, try connection per Fi ure 2 first. If T/R faults
occur, try Fi ure 3.
33 ALC
The ALPHA 86 enerates a rid-current-derived, ne ative- oin (from zero) DC control volta e that can
be fed back to most transceivers to avoid overdrive. To take advanta e of ALC, connection must be made to
the ALPHA 86 rear panel ALC jack.
Any rid current excursion above approximately 70 mA will "tri er" the ALC. At about 100 mA, ALC
output is nominally -10 VDC. If the transceiver requires less volta e a 100 kohm potentiometer may be
connected across the center pin of the ALC jack to chassis. The potentiometer wiper will provide an adjust
able "feed" to the transceiver. While drivin the amplifier the potentiometer can be adjusted to limit trans
ceiver output to keep the amplifier rid current less than 100 mA.
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