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301. Re: [TenTec] OmniVI Plus Over Drive Amp (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 24 Jun 2008 10:14:09 -0600
Meters are generally rated with error a fixed % of full scale. Typical panel meters run 10%, some 3%, lab grade meters 1% or better. That's the meter alone. The couplers in a Bird add to the error bu
/archives//html/TenTec/2008-06/msg00410.html (10,454 bytes)

302. Re: [TenTec] TenTec 228 ATU (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 24 Jun 2008 10:26:15 -0600
The losses in a T-match are greatest when the loaded Q of the match is higher than necessary for the impedance transformation needed. This a condition easy to achieve because there are many L and C c
/archives//html/TenTec/2008-06/msg00411.html (11,413 bytes)

303. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 09:23:01 -0600
What is the fundamental cause of these failures? Are the capacitors poor to begin with, or is the circuit ripple or voltage excessive? Is there AC being applied to a DC capacitor? Is one wired in bac
/archives//html/TenTec/2008-06/msg00427.html (11,247 bytes)

304. Re: [TenTec] OmniVI Plus Over Drive Amp (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 09:34:47 -0600
Good points. Two problems. I have more confidence that the meter will indicate something with some reflected power, but the meter indication won't go to zero, providing Bird still gets good diodes wi
/archives//html/TenTec/2008-06/msg00428.html (12,094 bytes)

305. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 16:01:02 -0600
Then low ESR and high temperature rating are a benefit, but the fundamental is that the capacitors need to be rated FOR the ripple current. Good electrolytic makers know and publish such ratings. Som
/archives//html/TenTec/2008-06/msg00439.html (10,495 bytes)

306. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 16:34:52 -0600
Almost but it doesn't give a number for the heat transfer capability of the package. That is vitally important, the larger the case, the better that heat will be transfered to the air and environment
/archives//html/TenTec/2008-06/msg00440.html (12,906 bytes)

307. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 16:44:33 -0600
Work that Tentec apparently has failed to do. Looks like there are capacitors capable of giving long life in the circuit based on the computed and rated ripple current, and many that won't give a lon
/archives//html/TenTec/2008-06/msg00441.html (10,148 bytes)

308. Re: [TenTec] OmniVI Plus Over Drive Amp (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 25 Jun 2008 22:20:46 -0600
That meter tolerance is important. And the 30 microamp meter makes errors more likely because of pivot or taut band friction. There's not much horsepower available to fight the springs and pivot fric
/archives//html/TenTec/2008-06/msg00447.html (10,413 bytes)

309. Re: [TenTec] Mics for Pegasus NEWBE HERE HELLO ALL (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 26 Jun 2008 19:54:32 -0600
Amplified D-104 were made for the CB trade. The makers of CBs have decided to prevent over modulation by limiting the audio gain, to the point of killing communications range. Base stations talked be
/archives//html/TenTec/2008-06/msg00467.html (9,658 bytes)

310. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 26 Jun 2008 20:20:39 -0600
Computer grade caps were made with higher purity in the aluminum foil so bad spots didn't happen as often and they were also made to handle lots of ripple current. But electrolytics fail fastest when
/archives//html/TenTec/2008-06/msg00468.html (10,703 bytes)

311. Re: [TenTec] 555 Scout HELP (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 26 Jun 2008 21:37:49 -0600
Sounds like the PC board grounds need to be tightened by tightening all the PC board mounting screws. The tuned antenna presents a narrow band matched load. This trouble sounds like the Scout has som
/archives//html/TenTec/2008-06/msg00470.html (10,330 bytes)

312. Re: [TenTec] TenTec 228 ATU (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 27 Jun 2008 08:51:01 -0600
Do you know that switch was melted feeding a reasonable load or was it used to feed a short wire with a very low radiation resistance with more than the tuner's rated power? You can increase the band
/archives//html/TenTec/2008-06/msg00476.html (11,263 bytes)

313. Re: [TenTec] Orion II A9 Board Failure...Again! (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 27 Jun 2008 21:23:07 -0600
My capacitor book says, "an aqueous solution of ammonium borate, boric acid, and glycol." Its strong enough to eat the aluminum oxide created in the forming process. That mix sounds acidic. If the se
/archives//html/TenTec/2008-06/msg00481.html (10,121 bytes)

314. Re: [TenTec] TenTec 228 ATU (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Jun 2008 10:54:44 -0600
I'm talking transformer. This is a voltage device. No, just a 50 ohm resistor and I tested the input Z with a RX-meter and it was as narrow as a Pi network. Hardly covered one band. It was fairly lar
/archives//html/TenTec/2008-06/msg00488.html (12,981 bytes)

315. Re: [TenTec] TenTec 228 ATU - update (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Jun 2008 11:08:38 -0600
But not zero losses. That toroid will survive 100 watts, but not 1.5 KW. Switching in a low to medium Z output transformer can take care of low feed Z antennas, nothing new there, is especially handy
/archives//html/TenTec/2008-06/msg00489.html (9,124 bytes)

316. Re: [TenTec] OT: Toroid ratings / selection (was TenTec 228 ATU) (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 28 Jun 2008 21:00:45 -0600
In this application the impedances are forecast to be low and so that output transformer has a better chance. To the contrary, loaded Q has a great deal of influence on the efficiency. In any tuned c
/archives//html/TenTec/2008-06/msg00493.html (14,796 bytes)

317. Re: [TenTec] [Fwd: 555 help] - forwarded on behalf of KE6GFF/T6EE (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Mon, 30 Jun 2008 19:55:40 -0600
One other test for spurious outputs. Use the tuner on the dummy load. The tuner bandwidth will be similar to the tuner bandwidth on a nearly resonant antenna. If the tuner can't be tuned to a perfect
/archives//html/TenTec/2008-06/msg00509.html (8,996 bytes)

318. Re: [TenTec] Antenna Tuners...questions (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 02 May 2008 10:22:02 -0600
I'm not much of a fan of TV cable because it often uses aluminum foil and a bit of aluminum braid for the shield and getting and maintaining good connections are difficult. The shielded twin lead sch
/archives//html/TenTec/2008-05/msg00040.html (10,679 bytes)

319. Re: [TenTec] TR problem with Omni-V (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 03 May 2008 18:40:25 -0600
Is there a switch on the back to select receiver on the transmit antenna or separate? In some Tentecs that switch has caused exactly your symptoms. Contacts need cleaning. A part drop of DeoxIT helps
/archives//html/TenTec/2008-05/msg00064.html (8,740 bytes)

320. Re: [TenTec] Baluns (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Mon, 05 May 2008 10:14:19 -0600
You use a voltage balun when you want the balun to force the balance, even if the antenna isn't quite balanced. Works many times and works well if the antenna is balanced. You use a current balun whe
/archives//html/TenTec/2008-05/msg00101.html (8,929 bytes)

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