Battery Source

Hi,
Just to dive in here, with a slightly off track comment. The
benefits of extra
voltage on the radio transmit are not worth the effort. A quick trawl
through
the figures shows that you need to make an x10 output improvement in output
to
hear/notice it at the other end.

Changing the coax feeding the antenna to a good quality low loss grade,
followed
by tuning the antenna for the frequency range your using, would give more
useful benefits. The receive improvement gained here, is also not to be
sniffed at.

I wonder how many have put a VSWR meter on their setup? Any SWR above 1.5
is going to be a detrimental. On most gliders I would estimate that the
power reaching
the antenna is only 50% of that, that left the radio!!

Malcolm - G3REM (but only a poor, K6 pilot)



"T o d d P a t t i s t" wrote in message
...
"bumper" wrote:

By the time most modern radios would start to falter, the battery is
already
pretty much discharged. Using an up-converter is this circumstance would
only result in a very limited amount of additional radio use - - along
with
a very discharged battery!

I don't think he was advocating an up-converter to increase
voltage when the battery was dying. I think he was
suggesting it for the additional transmitted power you would
get from 14 volts even when the 12V battery is fresh. Even
if it was practical (which I doubt) you'd be losing battery
capacity to gain the higher voltage - that's probably not a
good trade-off for reasons discussed in Tim Mara's post.


T o d d P a t t i s t - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

Changing the coax feeding the antenna to a good quality low loss grade,
followed
by tuning the antenna for the frequency range your using, would give more
useful benefits. The receive improvement gained here, is also not to be
sniffed at.

Just how do you tune an antenna? In the old CB days we would ajdust the
lenght of the antenna until we got a good SWR. I can't see cutting into
the tail of my LS6 to do that.

Tony V.

Tony Verhulst wrote:

Changing the coax feeding the antenna to a good quality low loss
grade, followed
by tuning the antenna for the frequency range your using, would give more
useful benefits. The receive improvement gained here, is also not to
be sniffed at.

Just how do you tune an antenna? In the old CB days we would ajdust the
lenght of the antenna until we got a good SWR. I can't see cutting into
the tail of my LS6 to do that.

Tony V.

I measured it in my LS4 once, and saw something really good, about 1.1:1.

If Malcolm believes you need a 10X factor in transmitter power to make
a noticeable improvement, then I suppose he'd also believe you need to
increase the radiated power 10X by tuning in order to make a difference.
No factory installation is going to be subject to that kind of
improvement, unless you have an open or short somewhere in the system.

-Dave

T o d d P a t t i s t wrote:
Eric Greenwell wrote:


Does such a converter exist?

Yes; in fact, modern radios often have exactly this kind of power supply
built into them (my Becker transponder is an example of this).

Does your Becker upconvert the voltage to the power output
transistors, or just the control electronics?

I'm sure it controls the voltage to the output stage. Whether it's
upping or downing it probably depends on the input voltage (supply
voltage is given at 9.5-32.2 volts), but I don't know what voltage the
output stage operates at. The rest of the radio might could just use a
voltage regulator off the incoming voltage, but again, just a guess.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

That is just pure nonsense (the up vs down part). You can buy a 30W
(15V @ 2A) dc-dc converter for $62 from Mouser (search for
UHE-15/2000-Q12). The description says the input is 24V, but it really
is 9-36V, which should cover just about any battery you want to come up
with. The thing is 88% efficient and occupies 1.5 in^3. You can buy
lower power ones even cheaper. If that makes your 14V heart feel
better, go for it (it won't damage your radio).

Tom Seim
2G DG-400

Eric Greenwell wrote:
Graeme Cant wrote:

What about getting the best of both worlds? It seems agreed that only
the radio's performance improves with higher voltage. Why not keep a
12V system with its easy charging and standard sizes but add a DC-DC
UP converter into the radio circuit so that a constant 13-14V is
supplied to the radio even though the battery supply voltage drops?


Does such a converter exist?

Yes; in fact, modern radios often have exactly this kind of power supply
built into them (my Becker transponder is an example of this).

The truth is virtually no aircraft radios have upconverters built into them.
They switch high currents at high voltage at low RF frequencies. A nasty
thing to be building into a radio with a sensitive receiver. The converters
put out harmonics from their high-power square waves going well into the
aircraft band.

The only reason transponders have them built in is they have to generate
high voltage internally to create the multi-hundred watt pulses they put out.
Certainly not to humor a bunch of glider pilots too cheap to put together
a decent battery.

-Dave

Another interesting observation:

In a recent evaluation of our club's glider batteries (all 7AH
12v), we observed a very significant variation in weight. Is it
reasonable to deduce that a light battery cannot provide the same
hours of operation as a well designed heavier battery of the same
physical size? If so then we should also be watching out for
cheap-and-nasty batteries, where the manufacturer is skimping on
the lead content!

Cheers,

Jim Kelly.



"Malcolm Austin" wrote in message
...
Hi,
Just to dive in here, with a slightly off track comment.
The
benefits of extra
voltage on the radio transmit are not worth the effort. A quick
trawl
through
the figures shows that you need to make an x10 output improvement
in output
to
hear/notice it at the other end.

Changing the coax feeding the antenna to a good quality low loss
grade,
followed
by tuning the antenna for the frequency range your using, would
give more
useful benefits. The receive improvement gained here, is also
not to be
sniffed at.

I wonder how many have put a VSWR meter on their setup? Any SWR
above 1.5
is going to be a detrimental. On most gliders I would estimate
that the
power reaching
the antenna is only 50% of that, that left the radio!!

Malcolm - G3REM (but only a poor, K6 pilot)



"T o d d P a t t i s t" wrote in
message
...
"bumper" wrote:

By the time most modern radios would start to falter, the
battery is
already
pretty much discharged. Using an up-converter is this
circumstance would
only result in a very limited amount of additional radio
use - - along
with
a very discharged battery!

I don't think he was advocating an up-converter to increase
voltage when the battery was dying. I think he was
suggesting it for the additional transmitted power you would
get from 14 volts even when the 12V battery is fresh. Even
if it was practical (which I doubt) you'd be losing battery
capacity to gain the higher voltage - that's probably not a
good trade-off for reasons discussed in Tim Mara's post.


T o d d P a t t i s t - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

wrote in message
oups.com...
That is just pure nonsense (the up vs down part). You can buy a 30W
(15V @ 2A) dc-dc converter for $62 from Mouser (search for
UHE-15/2000-Q12). The description says the input is 24V, but it really
is 9-36V, which should cover just about any battery you want to come up
with. The thing is 88% efficient and occupies 1.5 in^3. You can buy
lower power ones even cheaper. If that makes your 14V heart feel
better, go for it (it won't damage your radio).

Tom Seim
2G DG-400


Get one of these for $45 and it will take your 12 V input and upconvert it
to 14V, handle 2A and be about 83% efficient.

http://www.dimensionengineering.com/AnyVolt.htm

I wish I had been available two years ago when I built my own 13.9V
upconverter.

Jim Vincent wrote:
wrote in message
oups.com...

That is just pure nonsense (the up vs down part). You can buy a 30W
(15V @ 2A) dc-dc converter for $62 from Mouser (search for
UHE-15/2000-Q12). The description says the input is 24V, but it really
is 9-36V, which should cover just about any battery you want to come up
with. The thing is 88% efficient and occupies 1.5 in^3. You can buy
lower power ones even cheaper. If that makes your 14V heart feel
better, go for it (it won't damage your radio).

Tom Seim
2G DG-400



Get one of these for $45 and it will take your 12 V input and upconvert it
to 14V, handle 2A and be about 83% efficient.

http://www.dimensionengineering.com/AnyVolt.htm

I wish I had been available two years ago when I built my own 13.9V
upconverter.

Did you use it with your glider transceiver? How has it worked out, and
do you have any problems with noise in the receiver from the converter?


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Hi,

It is my belief that all the work required to make an "upconverter" will
lead to only minimal increases in your radios transmit power (10 to 20%?).
It doesn't seem worth it to me. I vote 12V.

Paul Remde

"Jim Vincent" wrote in message
. ..

wrote in message
oups.com...
That is just pure nonsense (the up vs down part). You can buy a 30W
(15V @ 2A) dc-dc converter for $62 from Mouser (search for
UHE-15/2000-Q12). The description says the input is 24V, but it really
is 9-36V, which should cover just about any battery you want to come up
with. The thing is 88% efficient and occupies 1.5 in^3. You can buy
lower power ones even cheaper. If that makes your 14V heart feel
better, go for it (it won't damage your radio).

Tom Seim
2G DG-400


Get one of these for $45 and it will take your 12 V input and upconvert it
to 14V, handle 2A and be about 83% efficient.

http://www.dimensionengineering.com/AnyVolt.htm

I wish I had been available two years ago when I built my own 13.9V
upconverter.