Hi all,

We have a couple of XRF18085A LDMOS transistors here. Seem to be
pre-production samples of the MRF18085A by Motorola. But as the famous
M-logo is on the package I guess (hope) that these are full spec. samples.
They are to be used at around 1800 MHz and prematched for that band. I can't
find data for other frequencies. Has anyone tried these units (a solid 80
Watts out) on 23 cm?
Please advise.
Regards,
Harke PA0HRK

Hi Harke,

you are right with your assumption that the XRF is a pre-production sample.
After full qualification at the Motorola factory the transistores are named
MRF.

The MRF18085A is a 1800MHz final transistor for DCS-Basestation power
stages.
That means that Motorola is testing the parameters of this parts after
production
at this and only at this frequency (linearity, output power, compression,
....).

It should be no problem to use this parts at lower frequencies, it's still a
normal ldmos-trans.
What you can expect is more gain and a higher output resistance.
I had designed a 2m low power stage (3W) with the MRF281 which is built for
900MHz and higher
and it worked well.
The only problem could be to get the S-parameters for your frequencies, but
if you have
a good test equipment you should can do this job.

Chris OE3CJB


"Yrrah" wrote in message
...
Hi all,

We have a couple of XRF18085A LDMOS transistors here. Seem to be
pre-production samples of the MRF18085A by Motorola. But as the famous
M-logo is on the package I guess (hope) that these are full spec. samples.
They are to be used at around 1800 MHz and prematched for that band. I
can't
find data for other frequencies. Has anyone tried these units (a solid 80
Watts out) on 23 cm?
Please advise.
Regards,
Harke PA0HRK

Hi Harke,

you are right with your assumption that the XRF is a pre-production sample.
After full qualification at the Motorola factory the transistores are named
MRF.

The MRF18085A is a 1800MHz final transistor for DCS-Basestation power
stages.
That means that Motorola is testing the parameters of this parts after
production
at this and only at this frequency (linearity, output power, compression,
....).

It should be no problem to use this parts at lower frequencies, it's still a
normal ldmos-trans.
What you can expect is more gain and a higher output resistance.
I had designed a 2m low power stage (3W) with the MRF281 which is built for
900MHz and higher
and it worked well.
The only problem could be to get the S-parameters for your frequencies, but
if you have
a good test equipment you should can do this job.

Chris OE3CJB


"Yrrah" wrote in message
...
Hi all,

We have a couple of XRF18085A LDMOS transistors here. Seem to be
pre-production samples of the MRF18085A by Motorola. But as the famous
M-logo is on the package I guess (hope) that these are full spec. samples.
They are to be used at around 1800 MHz and prematched for that band. I
can't
find data for other frequencies. Has anyone tried these units (a solid 80
Watts out) on 23 cm?
Please advise.
Regards,
Harke PA0HRK