Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Wed, 14 Jul 2010 17:11:13 -0500
Look for fans with serrated blades, the are often quieter. But then just look at the specifications for the new fan for noise level. At Mouser (www.mouser.com) they run from 7 dBA to 78 dBA. I kind o
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 15 Jul 2010 14:46:30 -0500
Works well, even shows very coarse frequency information by the color of the glow. 73, Jerry, K0CQ _______________________________________________ TenTec mailing list TenTec@contesting.com http://lis
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 15 Jul 2010 16:17:01 -0500
Yup, a one turn loop about a quarter inch diameter at the end of a piece of coax works great for me for tracing current. The 10X probe would do just fine for tracing voltages. 73, Jerry, K0CQ _______
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 16 Jul 2010 22:46:32 -0500
If the counter shows that change, its the PTO. Likely a failure of voltage regulation. Which might be caused by dirty or loose connections on the power connector or something internal. I don't have m
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sat, 17 Jul 2010 19:03:11 -0500
Since those are digital filters there could be gain compensating factors, that are over compensating, or different styles of filters and the filter coefficients don't match the gain from one bandwidt
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Tue, 27 Jul 2010 20:41:22 -0500
Better yet, the voltage inside the transceiver. Power connectors have been known to give problems with high resistance to drop the voltage and give such chirp results. 73, Jerry, K0CQ _______________
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Tue, 27 Jul 2010 20:47:57 -0500
I don't have a manual on the 417, but if it uses external anode tubes like the Titan 425, it must have a centrifugal blower that produces 10 or 15 cpm at probably 3/4 or 1" water column pressure. The
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Tue, 27 Jul 2010 20:49:26 -0500
I think you have to take off all the knobs, maybe the end panels, and then the front panel, then you can take out the pot. 73, Jerry, K0CQ _______________________________________________ TenTec maili
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Tue, 27 Jul 2010 20:52:42 -0500
NO ANALOG NOISE BLANKER HAS EVER WORKED ON ATMOSPHERIC NOISE. The noise characteristics its made for are ignition noise and line noise that have a regular repetition rate but are made of isolated nar
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Wed, 28 Jul 2010 20:45:37 -0500
The pulses are transformer or capacitively coupled and shape filtered in that process which tends to be more repeatable with repetitive pulses. There's nothing in the analog circuit other than the pu
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 01 Aug 2010 17:44:06 -0500
The only trouble with not allowing the 10 KHz offset is that PTO mixing products get into the passband that were shifted out by that offset. The crystals are also shifted for those bands for the same
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 01 Aug 2010 18:07:11 -0500
I think the tentec of that era that preceded the Corsair and Corsair II that used a double gate mosfet mixer rather than a diode ring and super sturdy RF and IF amp stages didn't do as well in strong
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 01 Aug 2010 21:03:06 -0500
I was just guessing, sometimes I guess wrong. Mismatched diodes in the mixer can hurt. I really prefer in that case to break down and spend $5 on a MiniCircuits SBL-1 or SBL-1H if there's enough driv
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Tue, 03 Aug 2010 10:17:42 -0500
Looking at the VI manual, I'd connect at the cable between the RF and 9 MHz boards. There's a good buffer on the RF board, but a tuned circuit on the IF board to the 15 KHz filter. It might affect si
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 11:48:22 -0500
The purpose of these "baluns" is to attenuate any RF current on the outside of the shield. That helps cut feed line radiation when the coax is hooked to an antenna. Sometimes that helps cut TVI and r
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 12:43:30 -0500
When at the antenna, they do decouple the shield outside current and so act as a 1:1 balun the same as a quarter wave long decoupling sleeve or stub, common parts of balun construction. These balun c
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 17:20:42 -0500
I guess I'm using the term "beads" a bit figuratively taking into account toroids big enough to pass a coax connector on RG-213. For HF choking they need an initial permeability of a few hundred to 1
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 17:32:25 -0500
First thing you need is good short ground connections between units, often the coax performs that. If the equipment is fully shielded, there shouldn't be any RF on the outside of the coax, providing
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 17:44:21 -0500
No you haven't forced balance. You have allowed the grounded side of the feedline to float to pick a balance point mostly determined by the antenna. There is a considerable difference between allowin
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 06 Aug 2010 17:40:21 -0500
Of course there's lots of current in the braid, you made it nearly a half wave long. Try the same experiment with that braid 16 feet long and you will find much less current because then its a quarte