Zach, I think he was really asking why are the rx and tx not consistently distant from each other.  Part of the answer is doppler (UHF has more shift than VHF) but I think the annoying thing that we just have to deal with is that each time most linears come by you have to tweak the rx or tx to match even if you have exact keps, CAT, etc.  And I think the answer to that is just COTS parts in a really difficult environment.  Agree?

73,

Burns WB1FJ

On Mon, Aug 29, 2022 at 3:40 PM Zach Metzinger <zmetzing@pobox.com> wrote:
On 8/29/22 12:53, Calvin McDonald wrote:
> Why are the transponders not designed to hold the frequencies more exact??

Because it doesn't know how fast you are traveling, relative to its
position in space. That also applies for everyone else listening to it. :-)