I have a few old Radio Shack "engineer handbooks" that have a wealth of these circuits, 'cause I can never remember them. However, they are packed away still after moving. This site : http://www.kpsec.freeuk.com/trancirc.htm Seems to have mosteverything you'll need to invert the COS. Audio is another issue, The IC solution is probably best, less likely to build in distortion than with perfboard transistor circuit
Eric Lowell Eastern Maine Electronics Inc. 48 Loon Road Wesley ME 04686 [email protected] www.satnetmaine.com 207-210-7469 --- On Mon, 7/13/09, John Transue <[email protected]> wrote: From: John Transue <[email protected]> Subject: [Repeater-Builder] Need circuit -- COS Sense & AF Amplify [1 Attachment] To: [email protected] Date: Monday, July 13, 2009, 9:42 AM [Attachment(s) from John Transue included below] I need to interface a link receiver (Icom F221S) with an ACC RC-850. This presents two problems. First, the Icom receiver uses active low COS, and the RC-850 doesn't seem to have a means to select the sense of a link receiver. The repeater receiver (Midland BaseTech II) uses active high COS. Second, the discriminator audio output from the Icom is about 0.6 Vp-p, but the RC-850 hardware manual says the audio input should be between 1 and 5 Vp-p. I have posted the first problem to the ACC group but have received no reply. Yes, the ACC manual says to insert a 47K resistor in a specified place to increase sensitivity. I can do this but it requires I take the repeater out of operation for a day or so. It occurs to me that a circuit to reverse the sense of the COS might be available from this group. Also, a simple amplifier circuit could solve the AF level problem. I know this is all elementary, but I am not competent to design these simple circuits. I will gladly build them. I would appreciate any help you can provide on the design. Thanks. John Transue AF4PD
