Dave Platt wrote:

This looks like it would require 40 to 43 dB of gain to get to the level
that he needs for output.

Does anyone have suggestions of places to look on the web for application
notes and/or schematics for amplifiers along these lines?

I have done some searching on Google and found a few things but most of
them
take inputs of 30dBm or so and only take that level up to 40dBm. He still
needs to bridge the gap from 0 dBm to 30 dBm in that instance.

Hmmm. Seems to me that many of the VFO-and-mixer QRP CW/SSB
transmitter projects might have suitable designs... a few milliwatts
out of the mixer and bandpass filter, into a one- or two-gain-stage
driver which would then push power out to the final transistor(s).

Let's see. The Small Wonder Labs PSK-20 transmitters seem like a good
place to start looking. The schematic shows that the transmit
circuitry uses a Minicircuits TUF-1 mixer. According to the
Minicircuits web page, this takes as input a +7 dBm local oscillator
and up to 1 dBm of RF. It has a conversion loss in the 7-8 dBm range,
so you'd end up with somewhere around -6 dBm at most coming out of it.
The PSK-20 transmitter buffers this through a transistor, then through
a MAR-35M monolithic amplifier, and then through a 2SC1970 and
2SC1971, and ends up with 2.5 watts of power.

Seems to me that you could probably fiddle with this final stage a bit
(double up on the 2SC1971, heatsink 'em, run at a higher current
level, and adjust the driver circuitry to suit) and end up with 10
watts out.


Thanks for the information. I will check it out and pass it on to the
persons that were looking for it.

Al Butler
ka0ies

"Allan Butler" wrote in message
news:91vEb.426793$ao4.1361630@attbi_s51...
xpyttl wrote:

I was a little distracted by the main path of the conversation that we
were
having so I didn't ask at that time why they wanted 80 meters for a beacon
from that high. I also realize that it is going to take a fair amount of
battery to keep this thing going for any period of time.

These people do a lot with GPS. Maybe they are hoping to pass GPS
location
data to the ground crew after the payload lands so that they can go right
to it and pick it up. I have no idea what they are doing with antenna
ideas
or anything like that.

Now, what was his phone number? :-)

In the mean time thanks for the information. I will get to looking at it
and pass it on.

Al Butler
ka0ies

Al -

You have 2 very large helpful balloon organizations (NSTAR) in the Omaha /
Kansas City corridor ....
using GPS, VHF (2 meters, 70 cm, etc.) with VERY favorable results.

80 meters is a poor choice for project -- and 20 to 30 watts will be a power
hog (weight)
that is counter intuitive with what is trying to be accomplished.

LOW WEIGHT and HIGH PERFORMANCE are your criteria.

Check out the NSTAR light weight camera -- sending video at UHF to ground !
(you can't do this with 80 meters)

NSTAR
http://www.nstar.org/

Edge of Space Sciences
http://www.eoss.org/ansrecap/ar_060/recap55.htm

RCKARA
http://www.rckara.org/project_traveler/2001a/

NSTAR 2004 Flight Schedule
Future Flights
Here's our flight schedule for 2004. Those without a listed location will
be from our usual sites (near Treynor IA or west of Omaha NE).

a.. 04A - Mid to late February (SSTV scheduled)

b.. 04B - March 20 - Central Plains Severe Weather Symposium - Lincoln NE
(SSTV scheduled)

c.. 04C - April 17 - Strategic Air and Space Museum Family Day - Ashland
NE (SSTV scheduled)

d.. 04D - Mid to late May

e.. 04E - July 3 or 4 - Great Plains Super Launch - Hutchinson KS

f.. 04F - Mid to late August

g.. Perhaps 04G and 04H before the end of the year

W9GB

"Allan Butler" wrote in message
news:91vEb.426793$ao4.1361630@attbi_s51...
xpyttl wrote:

I was a little distracted by the main path of the conversation that we
were
having so I didn't ask at that time why they wanted 80 meters for a beacon
from that high. I also realize that it is going to take a fair amount of
battery to keep this thing going for any period of time.

These people do a lot with GPS. Maybe they are hoping to pass GPS
location
data to the ground crew after the payload lands so that they can go right
to it and pick it up. I have no idea what they are doing with antenna
ideas
or anything like that.

Now, what was his phone number? :-)

In the mean time thanks for the information. I will get to looking at it
and pass it on.

Al Butler
ka0ies

Al -

You have 2 very large helpful balloon organizations (NSTAR) in the Omaha /
Kansas City corridor ....
using GPS, VHF (2 meters, 70 cm, etc.) with VERY favorable results.

80 meters is a poor choice for project -- and 20 to 30 watts will be a power
hog (weight)
that is counter intuitive with what is trying to be accomplished.

LOW WEIGHT and HIGH PERFORMANCE are your criteria.

Check out the NSTAR light weight camera -- sending video at UHF to ground !
(you can't do this with 80 meters)

NSTAR
http://www.nstar.org/

Edge of Space Sciences
http://www.eoss.org/ansrecap/ar_060/recap55.htm

RCKARA
http://www.rckara.org/project_traveler/2001a/

NSTAR 2004 Flight Schedule
Future Flights
Here's our flight schedule for 2004. Those without a listed location will
be from our usual sites (near Treynor IA or west of Omaha NE).

a.. 04A - Mid to late February (SSTV scheduled)

b.. 04B - March 20 - Central Plains Severe Weather Symposium - Lincoln NE
(SSTV scheduled)

c.. 04C - April 17 - Strategic Air and Space Museum Family Day - Ashland
NE (SSTV scheduled)

d.. 04D - Mid to late May

e.. 04E - July 3 or 4 - Great Plains Super Launch - Hutchinson KS

f.. 04F - Mid to late August

g.. Perhaps 04G and 04H before the end of the year

W9GB

"Allan Butler" wrote in message
news:mRmEb.595184$Fm2.545419@attbi_s04...
Hi there.

Another Amateur that is involved with volunteering with schools and such
is
looking at launching a baloon with an HF transmitter on board. The band
of
operation is 80 meters. He is looking at some type of a beacon that will
send data via BPSK modulation and needs 10 to 20 watts of transmit power
at
the output port. For an input to the unit he has 0dBm or 1 milliwatt of
RF
at the operating frequency.

This looks like it would require 40 to 43 dB of gain to get to the level
that he needs for output.

Does anyone have suggestions of places to look on the web for application
notes and/or schematics for amplifiers along these lines?

I have done some searching on Google and found a few things but most of
them
take inputs of 30dBm or so and only take that level up to 40dBm. He still
needs to bridge the gap from 0 dBm to 30 dBm in that instance.

Any information that you can help with is greatly appreciated.

Al Butler
ka0ies

Here are the web page links for High Altitude Ballooning

http://users.crosspaths.net/~wallio/HABLinks.html

Ralph Wallio, W0RPK is a good resource
http://users.crosspaths.net/~wallio/

W9GB

"Allan Butler" wrote in message
news:mRmEb.595184$Fm2.545419@attbi_s04...
Hi there.

Another Amateur that is involved with volunteering with schools and such
is
looking at launching a baloon with an HF transmitter on board. The band
of
operation is 80 meters. He is looking at some type of a beacon that will
send data via BPSK modulation and needs 10 to 20 watts of transmit power
at
the output port. For an input to the unit he has 0dBm or 1 milliwatt of
RF
at the operating frequency.

This looks like it would require 40 to 43 dB of gain to get to the level
that he needs for output.

Does anyone have suggestions of places to look on the web for application
notes and/or schematics for amplifiers along these lines?

I have done some searching on Google and found a few things but most of
them
take inputs of 30dBm or so and only take that level up to 40dBm. He still
needs to bridge the gap from 0 dBm to 30 dBm in that instance.

Any information that you can help with is greatly appreciated.

Al Butler
ka0ies

Here are the web page links for High Altitude Ballooning

http://users.crosspaths.net/~wallio/HABLinks.html

Ralph Wallio, W0RPK is a good resource
http://users.crosspaths.net/~wallio/

W9GB

Allan Butler wrote:

OK here is what is going on as far as I know now.

The 3.5 MHz transmitter is to study sea wave propagation at that frequency
over sal****er at a defined altitude. I am not 100% certain what that means
but I will ask for more detail.

As to legality I will ask the person that I am getting the information for
what they have done in the way of research on this part. This group is
normally very good on researching these matters. It might be that they will
actually have the transmitter commanded from a UHF control link. I just
don't know for certain.

I will also pass on the information about the organizations that are doing
the balloon launches. It is always helpful to learn from other people.

Thanks for all the information so far folks. If there is anymore avaialble
please post it here to the news group so that we can all learn from each
other.

Al Butler
ka0ies

Allan Butler wrote:

OK here is what is going on as far as I know now.

The 3.5 MHz transmitter is to study sea wave propagation at that frequency
over sal****er at a defined altitude. I am not 100% certain what that means
but I will ask for more detail.

As to legality I will ask the person that I am getting the information for
what they have done in the way of research on this part. This group is
normally very good on researching these matters. It might be that they will
actually have the transmitter commanded from a UHF control link. I just
don't know for certain.

I will also pass on the information about the organizations that are doing
the balloon launches. It is always helpful to learn from other people.

Thanks for all the information so far folks. If there is anymore avaialble
please post it here to the news group so that we can all learn from each
other.

Al Butler
ka0ies

On Fri, 19 Dec 2003 16:57:48 GMT, Allan Butler
wrote:

Allan Butler wrote:

OK here is what is going on as far as I know now.

The 3.5 MHz transmitter is to study sea wave propagation at that frequency
over sal****er at a defined altitude.

Well then you're stuck with 80 meters. But I'd guess 5W output would
be plenty for your purposes. However, I'd be very interested in the
type of antenna you eventually settle on for this unusual purpose.
Nothing really springs to mind as being particularly suitable...
--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

On Fri, 19 Dec 2003 16:57:48 GMT, Allan Butler
wrote:

Allan Butler wrote:

OK here is what is going on as far as I know now.

The 3.5 MHz transmitter is to study sea wave propagation at that frequency
over sal****er at a defined altitude.

Well then you're stuck with 80 meters. But I'd guess 5W output would
be plenty for your purposes. However, I'd be very interested in the
type of antenna you eventually settle on for this unusual purpose.
Nothing really springs to mind as being particularly suitable...
--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

Paul Burridge wrote:
On Fri, 19 Dec 2003 16:57:48 GMT, Allan Butler
wrote:

Allan Butler wrote:

OK here is what is going on as far as I know now.

The 3.5 MHz transmitter is to study sea wave propagation at that frequency
over sal****er at a defined altitude.

Well then you're stuck with 80 meters. But I'd guess 5W output would
be plenty for your purposes. However, I'd be very interested in the
type of antenna you eventually settle on for this unusual purpose.
Nothing really springs to mind as being particularly suitable...

Zeppelin Antenna comes to mind. It was invented for this purpose.
If you can do with a wire antenna hanging off the baloon about 60m
down is another story.

Kind regards, Eike