[aprssig] FT-107M and HF APRS
Stephen H. Smith
WA8LMF2 at aol.com
Mon Nov 1 00:09:42 CST 2004
Norm McMillan wrote on 10/30/2004, 6:36 PM:
> Unfortunately I'm now faced with the FT-107M not transmitting on the
> WARC bands! I'm wondering if this is a *feature* which can be
> circumvented somehow.
This radio is an old ham-bands-only type design from the late '70s/early
'80s that predates the continuous-coverage 0-30.0 MHz design of modern
radios. Modern continuous-coverage designs are inherently capable of
transmitting through their entire range; the TX ability is arbitrarily
locked out in software, and can usually be re-enabled by cutting a diode
or PC board trace.
Older ham-bands-only radios would require extensive HARDWARE mods that
would involve: removing one existing band from the bandswitch (probably
40M or 20M), adding new tuned circuits and a new band-segment oscillator
crystal to place a new 10 MHz band in it's place, and finally wire
jumpers to cause the correct PA low-pass filter to be activated when the
new band is selected.
Unless you are lucky and the radio has a "WWV" position at 10 MHz
instead of 15 MHz. [ Many of these older radios received WWV at 15 MHz
since they could use the same front-end preselector tuned circuits as
the 14 MHz band. ] It might then be a fairly trivial process to defeat
a "receive-only" interlock. Since the VFO tuning range on most of these
classic "ham-bands-only" rigs had a 500 KHz tuning range, a "10 MHz" WWV
band would probably tune 10.0 to 10.5 and would easily cover the 10.1 to
10.15 30M band.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
New symbols for UI-View and http://members.aol.com/wa8lmf/ham
More information about the aprssig