On 22 mar, 16:50, (Michael Black) wrote:
Jean-Daniel HB9AKQ ) writes:
Hello,

I am in the process of choosing a technology for a crystal filter in
that frequency range. I am facing the choice of buying a filter and
paying the price, or to build a filter myself.

Are you hoping/expecting to get a narrow filter out of this, or will
it be a roofing filter, with the real selectivity at a different frequency?

I thought there were limitations on selectivity at those frequencies.
I can't recall ever seeing a narrow filter up there (and while it's been a
long time since I read that QST article, which is the only article in
the ham magazines that I've seen about making crystal filters that high
up, I thought it addressed that issue).

If it's just a roofing filter you need, you can pull one out of an older
cellphone. *The big clunky kind have parts that are recognizable.

* *Michael *VE2BVW

Hello, I need a roofing filter with a few kHz wide that can withstand
1dBm or a little more.
I am not sure that the MQF you find on the market or in older
cellphones can do that. The frequency should be between 45 and 80 MHz
and the price should be right. What is your experience on this?

Thanks
Jean-Daniel HB9AKQ