Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...
Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...
Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

It can actually be much simpler these days using a minicircuits vco (50R output)
and a pll chip, not a lot else to it really.

10mW would give you a fair old range line of sight.

Stick a minicircuits ERA 80mW device (4 legs, 50R in, 50R out) on the output of
the vco if you want a bit more umpf.

Just as easy on 70cms or the unlicensed 458MHz ISM band, same for 23cms and 13cm
or 2.4GHz ISM band. It's SO EASY these days with the building blocks you can
get.

Clive

It can actually be much simpler these days using a minicircuits vco (50R output)
and a pll chip, not a lot else to it really.

10mW would give you a fair old range line of sight.

Stick a minicircuits ERA 80mW device (4 legs, 50R in, 50R out) on the output of
the vco if you want a bit more umpf.

Just as easy on 70cms or the unlicensed 458MHz ISM band, same for 23cms and 13cm
or 2.4GHz ISM band. It's SO EASY these days with the building blocks you can
get.

Clive

Can anyone provide some part #'s for these one chip FM TX & RX IC's? I'm
interested too.

Marcus Sleightholm wrote:
Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...

Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

Can anyone provide some part #'s for these one chip FM TX & RX IC's? I'm
interested too.

Marcus Sleightholm wrote:
Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...

Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

In article ,
says...
Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available

that must be why i have a hard time finding the MC3361 or maybe it was
the 3362 used in RC aircraft receivers. Motorola sold the Mosaic line
and it's hell trying to find 'em. yeah, i know. they're receivers. but
it's still from the Mosaic line.

what suppliers do you suggest? i used some parts search engines and the
number in stock varies from day to day.

mike

and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...
Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

In article ,
says...
Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available

that must be why i have a hard time finding the MC3361 or maybe it was
the 3362 used in RC aircraft receivers. Motorola sold the Mosaic line
and it's hell trying to find 'em. yeah, i know. they're receivers. but
it's still from the Mosaic line.

what suppliers do you suggest? i used some parts search engines and the
number in stock varies from day to day.

mike

and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...
Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB

In article , says...
Can anyone provide some part #'s for these one chip FM TX & RX IC's? I'm
interested too.

MC2831A, MC2833, MC13175, MC13176. i got samples of one of 'em a long
time ago, but as i said in another post, motorola sold the Mosaic line
to either Micro-Semi or On Semi. either way, it's hard to pick a chip
for an app without the data sheet. before you ask me to scan and e-mail
them to you, tell me how to get my HP scanjet 3c to run on w2k and XP.
HP doesn't even know how to make work on win9x. the website has software
for 9x, but they fail to mention that you have to install DOS software
first. That doesn't work with NT systems like 2k/XP.

mike c

Marcus Sleightholm wrote:
Motorola did a number of one chip FM TX ICs, - they are cheap and widely
available and produce about 50mW output which can be use to drive something
like a 2N3866 output stage (I only give that device number as I have one in
the junk box!)

73 Marcus M3ChB

"R C" wrote in message
m...

Hi, I'm looking for a small, 2m FM fixed frequency TX design for a
backup telemetry link on a model craft. I've seen designs based on
discontinued Motorolla baby-monitor ICs, but simple varactor/tripler
designs seem less common. Weight/size are important, and I'd like
output around 1-2W. Duty cycle will be fairly low. There is 4.8V or
12V available already; 4.8V is likely to be noisier, as it drives the
servos. 12V is prefered.

What I was thinking was ~48 Mhz crystal oscillator with varactor, fed
into a tripler, then a bandpass, then into an amplifier (RF
transistor?)?

I've seen a number oscillator designs floating around (handbook and
otherwise), but I don't know how to find out what's most appropriate.
Any suggestions, designs I've missed, books to read, etc? Something
like the Ramsey FM6 (preraid)?

Plan B is to find another HTX-200 or similar, pull out the guts, and
use that. But I'd rather have something I can lay out myself.

Thanks,
R C
KG4MVB