Portable/back up transceiver

RST Engineering - JIm schreef:

NiMH a
c. Are relatively inexpensive (check out thomasdistributing.com)

Jim, thanks for enlightening me on the ecological aspect, I must admit I
never looked into that. Could it be you are in Caleefornyeah?

As for the economic side: that must depend much on location. I never did
any research, but have a feeling that NiMH is rather expensive here in
Europe, plus requires special charger.

Of course NiMH have better capacity, but Murphy says they'll be full
anytime anyway, except when you need them.

"jan olieslagers" wrote in message
...
Of course NiMH have better capacity, but Murphy says they'll be full
anytime anyway, except when you need them.

That's why I don't particularly like rechargeables of any type for emergency
use. A good fresh set of non-rechargeable alkalines will give you about 5
years of shelf life depending on how they are stored and lithium batteries
will last a bit longer. The manufacturers sometimes spec 10 years or more
on lithiums, but you're getting down to 50-70% of capacity at that point
which is not exactly what I'd like to be thinking about in IMC. Most of the
portable transceivers have battery pack options that allow you to use
alkaline or lithium batteries along with rechargeables. It's very nice to
have both packs so you can swap them around when you're using the
transceiver for non-emergency uses.

Enough about batteries. Want portable/back up comm recommendations -
Icom, Sporty's etc? Have portable GPS, so Nav is not that important.

On Jul 27, 9:32*pm, bobengr wrote:
Enough about batteries. *Want portable/back up comm recommendations -
Icom, Sporty's etc? *Have portable GPS, so Nav is not that important.

You can't go wrong with Icom. I have had an A2 for over 20 years, and
have had no trouble (other than batteries). Don't waste your money on
an optional
Nav function.

Regarding batteries, I use alkalines exclusively. Rechargeables need
to be cycled regularly (run down then charged up) to be dependable.
The batteries
in a backup tranceiver tend to see only very occasional use (with long
periods of neglect in between). Alkalines have an excellent shelf
life. The only
downside is that they have a higher internal resistance, and don't put
out current as well as the others. That translates into "use low power
on transmit
unless absolutely necessary to use high power".

Dave

"bobengr" wrote in message
...
Enough about batteries. Want portable/back up comm recommendations -
Icom, Sporty's etc? Have portable GPS, so Nav is not that important.

I had a Vertex that failed completely after about 5 years. I now have the
Icom A4 and I like it just fine. It's no longer being made, but you can
still find them for sale new. It's been replaced by the A14. I think it
might have a slightly lower power output than most, but it wasn't enough
that I could notice any difference compared to my old Vertex. None of them
work very well unless you're reasonably close to the ATC radio anyway,
although if you have an externally mounted antenna you can increase your
range somewhat. All of them are limited by power output, so most are going
to have virtually the same range.

Given the fact that a 1 watt transmitter on one end and a 1 microvolt
receiver on the other end have a maximum theoretical range of 1800 miles,
how in the world can you say that a 4 watt transmitter is "limited by power
output"?

The limitation is always by line of sight or antenna configuration.

Jim


"Mike" nospam @ aol.com wrote in message
...

.. I think it
might have a slightly lower power output than most, but it wasn't enough
that I could notice any difference compared to my old Vertex. None of
them work very well unless you're reasonably close to the ATC radio
anyway, although if you have an externally mounted antenna you can
increase your range somewhat. All of them are limited by power output, so
most are going to have virtually the same range.

"RST Engineering - JIm" wrote in message
...
Given the fact that a 1 watt transmitter on one end and a 1 microvolt
receiver on the other end have a maximum theoretical range of 1800 miles,
how in the world can you say that a 4 watt transmitter is "limited by
power output"?

The limitation is always by line of sight or antenna configuration.

Since all transceivers of this type are limited by the FCC in regards to how
much power they can output(and most of them develop the max power allowed at
about 1.5w nominal) and since all of them come with essentially identical
omnidirectional antennas, I can pretty much assume they will all have very
similar ranges, since obviously the transmitter is going to be the limiting
factor seeing as how the other end is putting out roughly 7db more power.

So you can use the opportunity to mentally masturbate your "engineering"
knowledge and talk about theoretical true parabolic reflectors and receiver
sensitivities that don't even approach practical applications, but you're
not really contributing much to the OP's question.

"Mike" nospam @ aol.com wrote in message
...
"RST Engineering - JIm" wrote in message
...
Given the fact that a 1 watt transmitter on one end and a 1 microvolt
receiver on the other end have a maximum theoretical range of 1800 miles,
how in the world can you say that a 4 watt transmitter is "limited by
power output"?

The limitation is always by line of sight or antenna configuration.

Since all transceivers of this type are limited by the FCC in regards to
how much power they can output(and most of them develop the max power
allowed at about 1.5w nominal) and since all of them come with essentially
identical omnidirectional antennas, I can pretty much assume they will all
have very similar ranges, since obviously the transmitter is going to be
the limiting factor seeing as how the other end is putting out roughly 7db
more power.

So you can use the opportunity to mentally masturbate your "engineering"
knowledge and talk about theoretical true parabolic reflectors and
receiver sensitivities that don't even approach practical applications,
but you're not really contributing much to the OP's question.


I don't always agree with Jim; but he is absolutely right on this one.

When I worked as an avionics technicial, most of the problems that I saw
were ultimately wiring issues of the coaxial cables (frequently broken at
the antenna connector) and only occasionally degraded sensitivity of the
receiver. That was long ago, and more modern receivers should suffer far
less degradation.

The most entertaining case was a Bellanca on which one of the two comm
transceivers would successfully receive the tower frequency about 6 miles
from the airport and transmit just a little further. It turned out that
there was an in-line coax connector which had become disconnected and the
radio signals both transmitted and received were only through the braiding
of the coax cable!

Peter

"Mike" nospam @ aol.com wrote in message
...
Since all transceivers of this type are limited by the FCC in regards to
how much power they can output(and most of them develop the max power
allowed at about 1.5w nominal) and since all of them come with essentially
identical omnidirectional antennas, I can pretty much assume they will all
have very similar ranges, since obviously the transmitter is going to be
the limiting factor seeing as how the other end is putting out roughly 7db
more power.

There are various ways of measuring the output power of an AM transmitter.
One manufacturer's 1-watt transmitter may be much the same as another
manufacturer's 4-watt transmitter. There are other important issues, such
as the type and quality of the modulation and the audio processing. The
devil is in the details.

Actually, the quality of the receiver is (in general) more important than
transmit power.

In my experience, both Vertex and Icom are good brand names for that type of
equipment.

Vaughn

"Mike" nospam @ aol.com wrote in message
...

"RST Engineering - JIm" wrote in message
...
Given the fact that a 1 watt transmitter on one end and a 1 microvolt
receiver on the other end have a maximum theoretical range of 1800 miles,
how in the world can you say that a 4 watt transmitter is "limited by
power output"?

The limitation is always by line of sight or antenna configuration.



Since all transceivers of this type are limited by the FCC in regards to
how much power they can output(and most of them develop the max power
allowed at about 1.5w nominal)

47CFR87.131 gives the maximum power permitted in the VHF com band as 55
watts carrier. WHere do you get your misinformation?

and since all of them come with essentially identical
omnidirectional antennas,

An omnidirectional (isotropic) antenna is an impossibility, although we do
some mathematical "tricks" to reference all antenna gain to isotropic. Gain
(dbi - decibels above or below isotropic or dbd - decibels above or below a
dipole) by definition are 2.14 dB different, the dipole having gain
perpendicular to the elements of 2.14 dbi. Tell me what the form factor is
for an antenna putting out a radiation pattern resembling a grapefruit?


I can pretty much assume they will all have very
similar ranges, since obviously the transmitter is going to be the
limiting factor seeing as how the other end is putting out roughly 7db
more power.

Either you have no idea what you are talking about or it is well into
beer-thirty for you.



So you can use the opportunity to mentally masturbate your "engineering"
knowledge and talk about theoretical true parabolic reflectors

Who said anything about parabolic reflectors? I used a plain old ground
plane at both ends. 2.14 dbi gain.

End one. One watt AM carrier power into a ground plane. End two receiver
with one microvolt sensitivity for 10 dB S+N/N being fed by an identical
ground plane. If you like, you can replace the ground plane antennas with a
plain old straignt dipole with no measurable gain or loss. Actual range at
127 MHz. is 1366.7 statute miles.

How the hell do you think we talk to the space shuttle with essentially the
same equipment a few MHz. higher with 1 watt handhelds?


and receiver
sensitivities that don't even approach practical applications

Every transceiver on the market today will give you at least half a
microvolt for 10 dB S+N/N. I was being generous by saying a full microvolt,
which will give you a much better s/n ratio. Haven't designed many VHF
radios, have you sonny?


, but you're
not really contributing much to the OP's question.

Perhaps. Perhaps not. But at least I knew what the hell I was talking
about.

Jim