Message	Date	From	Subject
7788	2012-09-17 11:42:15	ha5rxz	A Sudden Thought About The HYCAS Project
I was looking through some details about the HYCAS project and something suddenly struck me. All the designs for IF strips I've seen use tunable IF transformers, normally at 9 MHz or 10.7 MHz, but the HYCAS just uses chokes in the first two stages with a wideband transformer in the third. What is the reason for this design decision? Peter HA5RXZ
7789	2012-09-17 12:03:45	Wes	Re: A Sudden Thought About The HYCAS Project
Hi Peter, The essential detail in the Hycas paper is the topology. That is, we can replace a conventional cascode that uses identical devices with one that has a mixture of device types. In this case, there was an advantage to doing so. The IF amplifier from the paper is one that used readily available parts and fit with a need. Using chokes allowed it to fit with a wide range of applications. We don't need large gain as much as we just need a wide AGC gain range. You could certainly build it with tuned interstages. Stability would then be a consideration. So Peter, analyze it, model it, build it, measure it, and then tell us about your results. 73, Wes w7zoi

Hi Peter,

The essential detail in the Hycas paper is the topology. That is, we can replace a conventional cascode that uses identical devices with one that has a mixture of device types. In this case, there was an advantage to doing so.

The IF amplifier from the paper is one that used readily available parts and fit with a need. Using chokes allowed it to fit with a wide range of applications. We don't need large gain as much as we just need a wide AGC gain range. You could certainly build it with tuned interstages. Stability would then be a consideration.

So Peter, analyze it, model it, build it, measure it, and then tell us about your results.

73, Wes
w7zoi