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Re: [TenTec] Omni VII first impressions....odd things i.e. SWR values

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Omni VII first impressions....odd things i.e. SWR values
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 21 Dec 2007 20:27:48 -0600
List-post: <mailto:tentec@contesting.com>
Would be interested to know what the output power is doing both with the internal meter and with a external meter when this event occurs. Does it behave the same way with ANT 1 and ANT 2? I trust that you have the AUTO TUNER off. This would aid in identifying the area of concern.

Again the way this internal meter system works, it is sampled and displayed via digital processing loop. Thus, due to time vs. calculation differences, using anything other than a solid carrier I would consider as non-valid. Also, I suggest connecting the radio with a known good jumper to the external meter, a known good jumper to a known good dummy load. And I'd check it on different bands. If the problem persists, I'd contact Paul at Tentec Service.

At he same time, I tried my radio on CW, 20 WPM, with the dummy load. The internal SWR indication was 2.4:1 when with carrier it shows 1.0:1. I also noted that on various bands, in CW at 20 WPM, the SWR was different from band to band with higher values SWR on 15M, 12M & 10M than on 160M, 80M & 40M. In all cases, solid carrier TUNE/PWR shows 1.0:1 on all bands and the external power meter shows 0 reflected watts.

I just went through this exercise with my Omni VII. Using the internal meter, in TUNE output power indicated 20W, press PWR and it reads 100 watts. I did this 10 times with identical results. Then changed the meter to SWR and perfumed the same test sequence. SWR indicted 1.0:1 at both power levels, 20 watts TUNE and 100 watts PWR

I then switched the 238 tuner inline between the load and the Bird 43P. Adjusted the tuner for 0 watts reflected on the Bird. The Tentec SWR indication was 1.0:1. I then changed the C value in the 238 tuner to show about 4 watts reflected {had to change slugs to read this low}which should have been a SWR of about 1.6:1. The Tentec SWR indicated 1.4:1. At a different SWR value being 100 watts forward and 10 watts reflected on the Bird, thus from the chart a SWR of 2.0:1 the Tentec SWR indication was 2.1 : 1. Darn close I'd say.

The Bird 43 P with a 250 watt element shows some 18 watts in TUNE and 90 watts in PWR on 75M. The load on the Bird meter is a 50.5 ohm Bird load. My Omni VII produces some 90 watts on 75M and a gradual decrease per band to 80 watts on 10 meters. The Vcc is 14 volts at the power supply and likely a few tenths less at the radio with the supplied Tentec full length power cable. I also noted that the supply amp meter indicated 19 amps for 90 watts output on 75M and 22 amps for 80 watts on 10 meters. For what ever that's worth.

73
Bob, K4TAX




----- Original Message ----- From: "Mike Bryce" <prosolar@sssnet.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, December 20, 2007 10:22 PM
Subject: Re: [TenTec] Omni VII first impressions....odd things


bob and the gang..

the problem is in the tune position.

press tune and the swr reads 5.6 to 1 or 9.99 to 1 or 1.1 to 1

every time I press tune, I get another reading...

you should see it dance in cw..

mike

Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
Note: No trees were killed in the sending of this message, but a
large number of electrons were terribly inconvenienced


On Dec 20, 2007, at 8:49 PM, Bob McGraw - K4TAX wrote:

I notice that the SWR indication on the radio does not seem to follow on
SSB.  However, in TUNE it tracks quite well up to about 5:1 or so.

This has been a comment about the power reading ability of the
bargraph as
well.  My opinion, not very important.  It's accurate in TUNE and SWR
carrier modes, but SSB is best described as "cute".

I use an external meter as well for power and SWR measurements.

73
Bob, K4TAX

----- Original Message -----
From: "Mike Bryce" <prosolar@sssnet.com>
To: "Discussion of Ten-Tec Equipment" <TenTec@contesting.com>
Sent: Thursday, December 20, 2007 1:17 AM
Subject: [TenTec] Omni VII first impressions....odd things


After reading the manual and getting a bit more comfy with the rig...
I've notice a rather strange thing

on transmit on any band, meter set to read SWR

the SWR shows really wrong values.. like 9:1 swr

checking cables, and then into a 50 ohm load while monitoring with a
Bird wattmeter, the SWR on the Omni VII shows values that are way out
of wack..

and as you key the radio, the SWR keeps changes. Sometimes, it shows
correctly, other times the SWR keeps changing along with the keying

Yes, yes, yes, i've checked cables and connections, when the radio's
SWR meter is kicking up, the bird wattmeter shows flat.

I've fixed the problem somewhat----I've set the meter to show power
out and not SWR.

anyone have any thoughts on this??

mike

Mike Bryce, WB8VGE
 the heathkit shop
SunLight energy systems
J e e p
o|||||||o


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