Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Sun, 03 Mar 2002 18:41:57 -0600
Better, use some hot air and freeze mist to identify the one bad capacitor watching out for temperature compensating capacitors that should move. Then fix the poor solder joints. The temperature comp
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu, 07 Mar 2002 11:11:17 -0600
Tom, I agree. And notice that all the NEC programs give antennas over ground 3 dB excess gain. They do this by presuming that the isotropic reference is located at coordinates 0,0,0 and half immersed
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Fri, 08 Mar 2002 09:04:25 -0600
I went by the library after ham club meeting last night and made a copy of the folded conical helix antenna. I've not digested it yet. My initial impression of the illustrations is that it tries to m
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Sun, 10 Mar 2002 20:44:30 -0600
Actually the K2 uses known good technology to achieve very good results. Complexity is not necessarily a sign of good technology, more a sign of technology for technology's sake. The other makers KNO
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Tue, 12 Mar 2002 02:45:49 -0600
www.mouser.com my printed catalog says 84 cents each for 1892 rated at 1000 hours life. Perhaps you might want to look at the 756. 2/3 the current, half the light, 15 times the life. $1.04 each. No m
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Tue, 12 Mar 2002 02:47:34 -0600
If a SWR bridge is going to mess up, its most likely at the highest frequency used. Also the closer you get to the cutoff frequency of a low pass filter, the more it will affect SWR. 73, Jerry, K0CQ
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Tue, 12 Mar 2002 15:03:55 -0600
Icom has been doing that: bring out a new model with more features to kill the used market price for at least 22 years since they couldn't figure out how to fix the manufacturing problems in their IC
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Wed, 13 Mar 2002 11:46:40 -0600
Once hit, the push to get up at any time of the night is great. Greater the greater the damage that first time. 73, Jerry, K0CQ -- Entire content copyright Dr. Gerald N. Johnson. Reproduction by perm
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu, 14 Mar 2002 11:33:56 -0600
Actually the two TenTec Corsairs did a decent job of getting the selectivity close to the antenna. The RF stage is a bipolar power transistor with RF feedback (the Anzac circuit), with a hefty double
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu, 14 Mar 2002 23:33:52 -0600
A DSP filter can have very linear phase response across the pass band. My DSP-59+ handles 20 wpm CW down to 50 Hz bandwidth without too much damage or ringing. The phase response is a design variable
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu, 14 Mar 2002 23:37:51 -0600
Art Collins' description of the next ham rig after the S-Line in about 1964 was networked with a small control box sending serial controls to a remotely mounted computer controlled radio. As far as I
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Fri, 15 Mar 2002 10:54:53 -0600
I don't know much about the computer. I thought it was a little successful. Art was the problem that did in the company. He ran the company as if it was still in his garage even though it had 20,000
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Wed, 27 Mar 2002 11:42:54 -0600
Last I looked RF parts sold 4CX1600B, has that changed? And other venders of Russian tubes tend to have them. Look for Svetlana or 4CX1500B. Google turned up: http://www.hfpower.com/_disc2/00000075.h
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Wed, 27 Mar 2002 22:58:09 -0600
Side of cereal box. Single sided blank PC board with the copper away from the blanker board. Hobby shop polystyrene sheet. Poster card stock. The paper items would be improved by a few coats of clear
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Thu, 28 Mar 2002 16:39:25 -0600
Better yet use a 12 volt transformer, schottky (or synchronous) rectifiers, and MOSFETs for the regulators and then you don't need a crowbar because the unregulated voltage is only 16 volts. 15 amp f
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Sat, 30 Mar 2002 11:56:10 -0600
It is possible to use regulator chips (LM2940 family) that need only a half volt head room. Later Scouts did that, I don't know about earlier ones. The frequency modulation at 12 volts is a hint that
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Sat, 02 Feb 2002 09:28:19 -0600
Many times an intermittent responds to alternated heat and cold. You need a source of heat, such as a hair dryer, and a source of cold such as the product "Freeze mist". The canned cold is available
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Sun, 03 Feb 2002 09:44:07 -0600
I've found some signals on the air at high speeds (one was a code practice station a couple years ago) where the dots became so shortened that they disappeared. That's a problem for copying high spee
Author: geraldj@isunet.net (Dr. Gerald N. Johnson, electrical engineer)
Date: Mon, 04 Feb 2002 22:27:07 -0600
The safest way to tune a tuner is with a Tuner Tuner from MFJ or the place that originated the noise bridge. Its a fixed tuned noise bridge with a switch to bypass it for transmitting. 73, Jerry, K0C