Hi Sean,
There's a wealth of "Ohm stuff" and technicalities to
Google for. Don't be deceived by how compact radios
like that are - they're as complex as computers and
can be damaged in a fraction of a second if you know
how (or not)!
The "impossible" always happens.
I really think it best to use the TH-F6a for
monitoring only. You could fix it to handlebars and
use an earspeaker (with quick release in-line
connector) that clips to the ear and won't block your
hearing.
Transmit with the radio you're licensed to use.
I'm in the U.K. but we have the equivalent to GMRS
(PMR446) and conditional licensing means screw not
with what the authorities allow (and limit) for very
good reasons. They have that universal habit (knack?)
of acting harshly when you least expect - and it can
seem outrageous if least informed casual users get
hammered as hard as worse offenders. Partly because
they rarely catch most others who cause the problems?
Our (dual band) version of the TH-F6a is the TH-F7e
but any such radio is built to work reliably IF used
as designed to. If not, how the radio will behave
isn't predictable and interference can be caused to
other services over surprisingly great distances.
Bands and frequencies are allocated very exactly and
many to essential services (employing people who may
be among those at your cycling event)!
I think your intentions are pretty good but you're at
a disadvantage in "unfamiliar territory". People in
this great hobby tend to be supportive and go that
extra mile for newcomers.
There's no doubt that local hams and clubs would put a
lot of effort into helping you directly. It would
also help them - especially if they're involved in
same or similar events because there's always a
shortage of motivated skilful people who can combine
talents.
Another example of not knowing leading to problems.
Driving behind the shapely wiggling ass of a cyclist -
only to find on overtaking that HE resents the
admiration!
We need International regulations about what cyclists
can wear to warn!
Fred.
--- "Sean T. Peotter" <sean@...> wrote:
> Fred,
>
> I think i understand, i am relatively new to this
> Ohm stuff and power but i think i understand it.
> with the limited use that i will be using with this
> (no more than 5 hours and definatly not a constant
> usage) is it your professional opinion that i could
> still damage the TH what that limited usage?
>
> thanks!!
>
> sean
>
>
> -----Original Message-----
> From: Fred [mailto:glenndriech@...]
> Sent: Monday, March 24, 2008 08:40 AM
> To: TH-F6A@...
> Subject: Re: [TH-F6A] GMRS bands
>
> "Blowing the finals" means a "F***ed" PA (power
> amplifier) stage because of excess heat and voltages
> 
>
> Take it that your radio's finals are designed for 50
> Ohms within ham band limits and need an antenna that
> is a 50 Ohm load. Outwith those limits, the PA
> output
> impedance may be very different from 50 ohms.
> Therefore the GMRS antenna may not match the PA when
> working out of the band it was designed for - even
> if
> the antenna presents as a 50 Ohm load.
>
> If the "finals" cannot transfer energy properly to
> the
> antenna, excess heat and damaging voltages can
> result.
> Despite protection circuits.
> The receiver input stage can also be damaged.
>
> Might, can and maybe are downside so why not play
> safe? I bet buying a GMRS hand-held would cost a lot
> less than repairing your TH-F6A!
>
> Regards,
>
> Fred.
>
> --- Mark <N2FLF@...> wrote:
>
> > I think he meant by transmitting out of the
> > ham band WITH a ham band antenna
> > you might damage the final output stage
> > by having a high SWR.
> > However, if you use an antenna designed to
> transmit
> > on those frequencies you should be OK.
> > 73, Mark
> >
> >
> > Sean T. Peotter wrote:
> >
> > > yes i do realize it, i have no choice for what i
> > am trying to
> > > accomplish.
> > >
> > > what do you mean by "blowing the finals"?
> > >
> > > sean
> > >
> > >
> > > -
> > >
> > > On Sun, Mar 23, 2008 at 7:58 AM,
> > otterouttawater
> > > <sean@...
> > <mailto:sean%40onsupport.org>> wrote:
> > > > Hi, i am planning on purchasing this radio
> > to be able to use it in
> > > > conjunction with the 462.5 GMRS bands after
> > i have gone through the
> > > > mod. my question is, is there a better
> > antenna to use for this
> > > > frequency?
> > > >
> > >
> > > You do realize that the radio is not type
> > accepted for GMRS so it's
> > > not legal to transmit there. Mods are not
> > needed for receive.
> > >
> > > Also, since it is outside the band it was
> > designed to work in, there's
> > > an increased risk of blowing the finals.
> > >
> > >
> >
> >
> >
>
>
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>
>
>
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