----- Original Message ----- From: "Bow" <[EMAIL PROTECTED]> To: "'Discussion of AM Radio in the Amateur Service'" <amradio@mailman.qth.net> Sent: Saturday, April 21, 2007 3:06 AM Subject: RE: [AMRadio] My Amplifer Quest took a strange turn today
Thanks Bill.. Any idea about the input impedance? For now, I will be running it with my Icom IC-718, so I need to figure out that interface! Bow W5EFR Have no idea what the input impedance might be. It has a SO-239 on the back as an input, so expect it will be somewhere around 50 ohms, but could be anything and will probably change with frequency. If you have a small antenna tuner, you might hook it up between the IC-718 and the input. Or, if not, hook up the IC-718 directly, but run it at low power (5 watts) and check the SWR. Frankly, I'd be surprised if it was a close match. You can set up a small coil and capacitor (L section) as input tuning without too much trouble if you wish. The amp will probably take much less than 100 watts to drive it to full output in normal operation. Don't overdrive the amp in AM. Recall that the carrier + sidebands take 4 x carrier PEP. If the amp is rated at 800 watts, don't run it at more than 200 continuous. You'll need a fan as the power transformer and tubes will heat up fairly quickly at that power level. I'd plan to run it at no more than 150 watts or so to keep things comfortable. Depending on the plate voltage, even that might be a little high. There is no reason to push the amplifier, you will be at an advantage over the 25 watts of the barefoot IC-718. To get a 3-db increase in a receiver, you need to double the power of the amplifier. +/- 50 watts won't make all that much difference if you are at the 150 watt level. Bill ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
