Typically an NE612 front end needs about 50mV of local oscillator. So, one transistor osc followd by a second transistor buffer/limiter can feed a two or three section bandpass filter to directly drive the ne612. Your entire front end could run on less than 5mA of current at 6v.

On Mon, Nov 7, 2022, 7:51 AM Ashhar Farhan <farhanbox@gmail.com> wrote:
The trouble with using the si5xxx PLLs is that they consume too much power for a cubesat. Typically 30mA. 
I am assuming you are shooting for a 10.7 MHz IF for 146 MHz RF frequency. If you flip to lower side injection, your local oscillator will now have to be around 135 MHz. This is the fifth multiple of 27 MHz crystal. Getting it to oscillate on the 5th overtone is tricky and unreliable. A better scheme is to use the oscillator at 27 MHz and feed it to a hard limiter that produces rich odd harmonics and filter out 135 MHz. For exact frequecy, you could get away with the CB crystals.
- f

On Mon, Nov 7, 2022, 6:52 AM Wendy and Terry Osborne <wandtosborne@gmail.com> wrote:
Hi Andy,

You could try https://www.hy-q.com.au/
Or  https://www.rakon.com/
It's a long time since I bought crystals but I have had good service
from both companies.
I was going to suggest International Crystals but it seems that they are
out of business.
Here is a good reference:
https://www.everythingrf.com/directory/rf-quartz-crystals

These days, I would suggest  using AMSAT's Linear Transponder module
(LTM) which is described in the 2022 AMSAT Symposium proceedings.
You can access this from the https://launch.amsat.org/ if you are a member.

"The AMSAT Linear Transponder Module" was presented by Burns Fisher,
WB1FJ. The LTM is a multi-use transponder board set designed for
universities and other partners launching cubesats who have need for a
communications component. Similar to the radio systems in Fox and GOLF,
the partnership provides easy downlinks for universities and a
transponder for amateurs.

Some years ago, I designed a simple analogue linear transponder the
prototype is detailed here.
https://www.dropbox.com/scl/fo/ivdkfd19bf68rda2y71ic/h?dl=0&rlkey=e4rng2cvq020jmsu2bwfi84mq
It may be of some interest.

73,

Terry Osborne ZL2BAC

On 7/11/2022 7:33 am, Andy Brian wrote:
> Hi,
>
> I'm looking for good source of crystals between 156.5 and 156.600MHz
> for build experimental
> linear transponder. Please for any got information or some other
> solutions.
> I received a few from marine scanners but it seems not 156Mhz
>
> BR Andy
>
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