EMRFD Message Archive 7788

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