TF3CY » 16f877 http://www.tf3cy.is Benedikt Sveinsson Tue, 13 Jul 2010 19:43:17 +0000 en hourly 1 http://wordpress.org/?v=3.0 600W – build prep http://www.tf3cy.is/archives/97 http://www.tf3cy.is/archives/97#comments Thu, 03 Dec 2009 14:19:56 +0000 tf3cy http://www.tf3cy.is/?p=97 So, I have now designed the filter board and calculated the values of each of the 6 filters. I have some 1000V silver dipped mica capacitors that I’m going to use, and have been adjusting the toroids to match them 100%. I decided to use 5 element low pass filters in stead of the 7 [...]]]> So, I have now designed the filter board and calculated the values of each of the 6 filters. I have some 1000V silver dipped mica capacitors that I’m going to use, and have been adjusting the toroids to match them 100%. I decided to use 5 element low pass filters in stead of the 7 element commonly used. I saw the design in the Ameritron ALS-600/1300 and according to Elsie filter modelling software they should work fine. PLEASE comment if you have something to say about this decision. I will post the filter calculation later when I finish transferring them from Elsie to some better form.

While @work, I played around making a block diagram of the amplifier + some front panel ideas.

The complexity of the control board startled me, I see that I have to multiplex some of the input/output. The 16f877 has 8 AD inputs, 2x full 8 bit GPIO. I’m compiling a list of all IO and I will probably for simplicity use one of the 8 bit bus for controlling the LCD. I want to keep the serial UART unused for future expansions (remote control), then I have to figure out how to get the band data from the xmit, I have some old QST article showing a PIC based antenna switch so I will probably just use that design. Using a 74hc374 tristate latch to multiplex one of the data buses will probalby be the choice.

I plan to fire up the amplifier next week for testing and start the output module into a dummy load. I will probably use a manual bandswitch to control the filters. I’m NOT going to start operating the amplifier without the control circuits, but I have xmas to look forward to now.. I finally have something to do ;P

So the info I’m now starting to look into is the ALC circuit, and the band data input from the transceiver.

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