Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 13 Mar 2009 10:22:46 -0600
Probably the way to do that is to apply for a job there. Full time. Otherwise, with a set of programming and debugging tools and a couple radios (I and II) that could be done anywhere. Its been hinte
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 14 Mar 2009 17:45:37 -0600
Insertion loss of the narrow filter is greater than the loss of the wide filter. So front end and IF gain is lower with the narrow filter. That's so pronounced that in some later radios, the narrow f
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Mon, 16 Mar 2009 16:30:00 -0600
Pins 1 and 7 on a 25 pin serial cable are chassis and signal grounds. They are always wired straight. 2, 3, 4, 5, 6, 8, and 20 are signals that are sometimes crossed. Much the same applies to 9 pin b
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 18 Mar 2009 08:38:46 -0600
The higher power is saturating the core of the balun. One of the hazards of tuning through the balun. You could add 1/8 th wave or 1/4 wave of feed line, or use link coupled balun that uses no balun.
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 18 Mar 2009 13:19:12 -0600
And if they don't have enough core cross section, they too can saturate. But saturation is more difficult achieve with only one turn per core. Their big claim to fame is that the allow the antenna to
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 19 Mar 2009 10:13:00 -0600
Yet, just like a transformer, the voltage across the choke is the same as the voltage on one side of the transformer, and one has to watch out for core saturation. Higher permeability cores can satur
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 21 Mar 2009 16:41:52 -0600
Happens in many Tentecs. The 20 MHz crystal in my Corsair II is 6.99 which means when the PTO readout says 21.320 that the PTO is at 5.330. 4*5.330 is exactly 21.320000 MHz. One tip I figured out whe
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 27 Mar 2009 19:57:06 -0600
Filter cutting at 200 to 300 Hz is common, putting the BFO at the 20 dB down point. Sounds as if the BFO alignment is further from the filter than that. But with a crystal calibrator, you can determi
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Mar 2009 13:27:19 -0600
The effect of the bandpass tuning depends on what filters are in use at 9 and 6.3 MHz. If the filters are of comparable bandwidths, moving band pass tuning off of zero narrows the receiver bandwidth.
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Mar 2009 14:56:06 -0600
I don't know about the bandpass filter knob. Didn't buy a V when I had a chance because I didn't like the way it shifts to LSB for CW. That's disaster in a VHF contest. I'm talking Band pass tuning.
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Mar 2009 21:19:05 -0600
True but if the response curve was run manually or with an audio spectrum analyzer like a PSK31 program, as I suggested a couple times, that ailing filter would have been discovered. We haven't exact
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 29 Mar 2009 15:28:49 -0600
In some Tentec radios there is a problem combining PTT return and microphone return and shield return, going to the PC board, not to the case and that injects RF into the audio board. The cure as I r
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 29 Mar 2009 15:42:08 -0600
Resolution is distinct from accuracy. What is the precision of the counter's clock? It can be as bad as 100 ppm which is a 100 Hz error at 1 MHz or 900 Hz at 9 MHz which is disastrous when aligning a