Not sure why I wasn't thinking about active matching so that could work. I haven't run the numbers yet but an L match with a stub inductor might work too. Trevor R.H. Clarke, K8TRC On Mon, Jul 6, 2020, 6:08 PM Tom Holmes <tholmes@woh.rr.com> wrote: > For a 1500 to 50 ohm conversion, I’d think an emitter follower output > stage would go from high to low Z, and a common emitter input stage would > got the other way. I know you want to avoid a custom PCB, but the losses of > any sort of transformer won’t be pretty, and the active circuits will be > unity gain or better. > > > > Assuming the LPF/BPF is 50 ohms in and out, more or less, those aren’t too > tough using air core inductors, so losses can be tolerable. ARRL handbook > should have some examples, although may have to go back a few years. I have > some old ones still. Is passband flatness or phase shift a potential issue? > > > > Tom Holmes, N8ZM > > > > *From:* Trevor Clarke <retrev@csh.rit.edu> > *Sent:* Monday, July 06, 2020 5:56 PM > *To:* Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com> > *Cc:* Tom Holmes <tholmes@woh.rr.com> > *Subject:* Re: [mvus-list] Looking for transformer core suggestions > > > > 30W is a separate but related question related to material for a transmit > lpf/bpf > > > > I was hoping to avoid a custom pcb and use microwave proto boards and > short traces. Frequencies are 50MHz and about 200MHz. Impedances are 50ish > ohm for interconnects and I/o impedance vary with device, up to 1.5k or so > > Trevor R.H. Clarke, K8TRC > > > > On Mon, Jul 6, 2020, 4:16 PM Tom Holmes via mvus-list < > mvus-list@lists.febo.com> wrote: > > What impedance ratio are you needing? > > A toroid of ferrite could work if you need some integer ratio, but if it is > more of a matching exercise, maybe a stripline would work better. The > ferrite is going to be a bit lossy. > > Not sure I understand it the <30W part is the same question or a separate > one. > > Tom Holmes, N8ZM > > -----Original Message----- > From: mvus-list <mvus-list-bounces@lists.febo.com> On Behalf Of Trevor > Clarke via mvus-list > Sent: Monday, July 06, 2020 3:25 PM > To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com> > Cc: Trevor Clarke <retrev@csh.rit.edu> > Subject: [mvus-list] Looking for transformer core suggestions > > What materials are good for impedance transformers for VHF? Say 2-5% > bandwidth and relatively low power.(matching receiver and transmitter > stages so uW to mW) if using in an output filter for <30W would you suggest > a different material? > > Trevor R.H. Clarke, K8TRC > _______________________________________________ > mvus-list mailing list > mvus-list@lists.febo.com > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com > > > > _______________________________________________ > mvus-list mailing list > mvus-list@lists.febo.com > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com > >