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As part of the transmitter alignment on my Icom751a, I need an Audio
frequency generator supplying tones at 1.3, 1.9 khz at 3mV - is there software out there that will do this? I have found some audio generator software but haven't seen where you can set the mV level any help is appreciated! thanks, Mike AB7RU |
#2
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In article ,
AB7RU wrote: As part of the transmitter alignment on my Icom751a, I need an Audio frequency generator supplying tones at 1.3, 1.9 khz at 3mV - is there software out there that will do this? I have found some audio generator software but haven't seen where you can set the mV level any help is appreciated! thanks, Mike AB7RU There's no universal way to do this, since PC sound cards don't have consistent output levels. Full-scale-digital output signals are often at 1- or 2-volts peak-to-peak on the line-level output jacks, but they're often at different levels depending on the PC's sound chip, amplifiers, whether there's a headphone amp involved, etc. In one case I encountered (my Dell Latitude CPxj) turning the PCM-out control all the way up to full scale resulted in horrible digital clipping of the signal, *before* the sound interface's master volume control. I had to turn the PCM output level down to about 30% to get a clean sinewave output. The best I can suggest is that you generate the tone that you need using the PC software you have, feed the line- or headphone-level output from the PC sound card to an analog volume control (a 1k or 10k audio-taper pot is probably a good choice), and use a reasonably well calibrated oscilloscope or DVM to measure the resulting voltage and trim it to 3 millivolts (P-P or RMS, depending on what the calibration procedure asks for). I'd recommend using a 'scope, to confirm that you're actually getting a clean signal. It's best to measure the actual signal level "in circuit", with the PC/generator and the attenuator driving the rig's transmitter. If you measure first and then attach to the rig, the rig's input impedance may shift the level enough to perturb your calibration procedure. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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