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341. Re: [TenTec] [Ten-Tec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Fri, 16 May 2008 16:43:50 -0600
Far as I can tell, they all work fine. Be sure to keep the coax between the filter and the transmitter short for best harmonic rejection. They aren't really hard to build using classic constant K and
/archives//html/TenTec/2008-05/msg00326.html (7,671 bytes)

342. Re: [TenTec] OMNI 6+ key clicks (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 18 May 2008 10:50:00 -0600
Be sure its not receiver overload. Many receivers do not handle really strong signals well. 73, Jerry, K0CQ
/archives//html/TenTec/2008-05/msg00372.html (7,751 bytes)

343. Re: [TenTec] AGN "clix" with OMNI 6+ (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 18 May 2008 10:55:43 -0600
Sounds like phase noise which can be as much a receiver problem as a transmitter problem. The biggest source of phase noise from the transmitter should be the VFO synthesizer. Be sure the receiver in
/archives//html/TenTec/2008-05/msg00373.html (8,638 bytes)

344. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 18 May 2008 11:54:11 -0600
The filter between the driver and the PA won't help harmonics detectably and may upset the match between the two units. 73, Jerry, K0CQ
/archives//html/TenTec/2008-05/msg00378.html (8,927 bytes)

345. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 18 May 2008 13:20:44 -0600
Yes and as close to the amp as possible, not with a few feet or more of coax between the amp and the filter. Keep that coax jumper under a foot. The PA running class B makes lots of harmonics even wh
/archives//html/TenTec/2008-05/msg00381.html (9,217 bytes)

346. Re: [TenTec] 95% Shield (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sun, 18 May 2008 20:50:20 -0600
Benzene was used for aircraft fuel in the 30s and in many parts of the world into the 1960s. Gulftane was benzene, freezes at 34 degrees. So its not used where freezing conditions are common. 73, Jer
/archives//html/TenTec/2008-05/msg00391.html (10,760 bytes)

347. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 09:50:09 -0600
Except that the class B operation of the PA device (for much greater efficiency than class A which is most linear) involves half cycle device conduction and that creates harmonics only a couple dB do
/archives//html/TenTec/2008-05/msg00409.html (16,673 bytes)

348. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 09:57:29 -0600
That is not necessarily true. Many a band pass filter is made of parallel and series resonant circuits (at the center frequency of the band pass) coupled together. Yes, but you have to watch for reso
/archives//html/TenTec/2008-05/msg00410.html (12,811 bytes)

349. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 10:11:09 -0600
The active devices do have gain at VHF. The input and output tuned circuits should keep that gain to the devices alone. That's why there are parasitic suppressors always in the plate, often other pla
/archives//html/TenTec/2008-05/msg00411.html (12,584 bytes)

350. Re: [TenTec] Orion 565 Oscillator frequency problem (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 10:40:40 -0600
Such frequency drift is a constant problem at VHF through microwave ham activities running SSB and CW. 3 ppm at 10 GHz is 30 KHz. The first help is isolation of the oscillator by hiding it in a block
/archives//html/TenTec/2008-05/msg00413.html (10,849 bytes)

351. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 11:36:31 -0600
And the french horn is the most treacherous with common valving for adjacent notes throughout much of its register. Like the top octave of the tuba. The parallels between radio and acoustics are far
/archives//html/TenTec/2008-05/msg00417.html (11,718 bytes)

352. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Tue, 20 May 2008 15:49:42 -0600
So you reach over with your free hand a slide the slide tuner in and out to fix the remaining errors. Many I've seen (but not mine) slide as easily as a trombone slide. My old Eb big bore Holton tuba
/archives//html/TenTec/2008-05/msg00428.html (11,848 bytes)

353. Re: [TenTec] 95% Shield (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 21 May 2008 15:24:43 -0600
Its been reported for nigh on 60 years that looking into a X band waveguide excited by a 20 or 50 milliwatt local oscillator klystron WILL make near instant cataracts in men or rabbits. That's not a
/archives//html/TenTec/2008-05/msg00450.html (9,590 bytes)

354. Re: [TenTec] Low Pass Filter (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 21 May 2008 21:15:11 -0600
I read that as the TV was local to the 160 meter station, but the interference only showed when the TV viewer tried to watch a TV station 70 miles away. Lots of F connectors are put on badly, and som
/archives//html/TenTec/2008-05/msg00458.html (9,167 bytes)

355. Re: [TenTec] A bit off topic...antenna question (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 21 May 2008 21:18:31 -0600
Be sure its for the band you want. A bazooka is basically a single band antenna. The bazooka puts a DC short on the coax. Sounds like the coax is shorted, either the feed line or in the antenna. That
/archives//html/TenTec/2008-05/msg00459.html (10,245 bytes)

356. Re: [TenTec] A bit off topic...antenna question (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 22 May 2008 10:34:32 -0600
So the antenna is shorted. Throw it out. Its junk and will break apart in the air and the added bandwidth is too small to pay for the complexity. Go get 66 feet of wire. Cut it into two pieces. Use t
/archives//html/TenTec/2008-05/msg00472.html (9,767 bytes)

357. Re: [TenTec] Titan 425 10 Meter Tune (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Sat, 24 May 2008 21:47:26 -0600
Find a PA tube with a bit lower output capacitance. Or move the ten meter tap on the coil a bit closer to the input of the Pi coil. You want to use minimum C from the variable or as close to minimum
/archives//html/TenTec/2008-05/msg00498.html (7,998 bytes)

358. Re: [TenTec] Omni VI problems, continued (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 28 May 2008 09:30:34 -0600
<SNIP> Mixer output or gain is dependent on adequate LO drive. Low LO drive can cause low output. Remember that in the classic TenTec mixing scheme, 80 and 20 use the VFO directly, while all other ba
/archives//html/TenTec/2008-05/msg00536.html (9,546 bytes)

359. Re: [TenTec] Omni 546 Series C RF power amp advice sought (long post) (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Wed, 28 May 2008 10:00:47 -0600
Rather if the low pass filters were relay switched, the RF drive caused the transistor collector voltage to swing higher than the transistors could stand, a collector failure, rather than a base fail
/archives//html/TenTec/2008-05/msg00538.html (16,487 bytes)

360. Re: [TenTec] Omni 546 Series C RF power amp advice sought (long post) (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Date: Thu, 29 May 2008 11:36:57 -0600
It probably won't have any effect at 80m but might be significant at 10m. That fits better. TT parts has often been a good source of those replacement parts at least until their stock is depleted. Th
/archives//html/TenTec/2008-05/msg00578.html (13,809 bytes)

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