Be sure to add a DC blocking capacitor to the input leads. The factory input runs right into the top of the pot. If you try to monitor any audio paths that have a DC bias on them, it will fry the volume pot. :( I would suggest at least a 4.7uF preferred non-polar.
I have one that I use on my bench that the 1/8" jacks have been removed so that red and black test leads may exit the unit. I do agree with skip that it is just the handiest darn thing!! Another "option" that I added was a small LED for a "power" indicator. I realize that it probably pulls about as much, if not more current than the rest of the circuit, but at least it's easier to remember when I've left it on. Scott Scott Zimmerman Amateur Radio Call N3XCC 474 Barnett Road Boswell, PA 15531 ----- Original Message ----- From: skipp025 To: Repeater-Builder@yahoogroups.com Sent: Tuesday, January 02, 2007 4:20 PM Subject: [Repeater-Builder] Mini Audio Amplifier time... Mini Audio Amplifier time... It would be some of the best money spent on handy test gear if many of you picked up a Radio Shack Mini Audio Amplifier. Part Number: 277-1008 http://www.radioshack.com/product/index.jsp?productId=2062620&cp Runs $12.99 and based on the time it will save you... well worth the buck'ola's you'll spend. You can use this handy beast for service, repairs and in the case of the last emph & de-emph thread/posts to actually hear the audio at various stages in your repeater system. Runs on 9 volts so it's easily portable. The two side mounted jacks allow you to use it for audio or even a line driver application. In the current solar repeater thread you wouldn't in even need to have the original equipment audio hardware installed. Just bring along the mini amp for testing... You can also remove the amplifier pc-board from the plastic case and install it in various project locations... temp or perm. I'm sure more than one of you have run into one of these amplifiers applied into a circuit temp and it was never removed or changed. When I speak to some of you on the phone about testing audio I always try to convey how handy this "little bugger" can be. Makes for easier trouble-shooting and if you're crafty enough to make an rf probe, it will detect and amplify various rf circuits/stages. Some of you might also harken back to the original Radio Shack "Signal Tracer", which is pretty much an equivalent function/device. If you don't have one... it might be the best $12.99 you've spent this month. Be sure to get the 9v battery and a 1/8 inch phono plug along with some shielded wire. Or buy the 1/8 inch on both ends jumper (from the shack) and cut it in half. cheers, s. > "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > Repeater audio amplifier stage to greatly reduce the standby > current, with a switch to re-enable the audio PA for maintenance > while at the site. ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.2/613 - Release Date: 1/1/2007 2:50 PM
