C25 failing on the Power Amp board. And failing by its decreased value of C
thus negating the controlled ramp as indicated below. Generally,
electrolytics decrease in capacity as they age.
"When the "T" line on the Power Amp board goes high, C25 in conjunction with
R17 delays the rise of the bias reference voltages, reducing the gain of the
PA until the rest of the transceive settles into a stable transmit mode."
73
Bob, K4TAX
----- Original Message -----
From: "Denton" <denton@oregontrail.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Cc: <n4py@arrl.net>
Sent: Saturday, December 03, 2005 10:42 AM
Subject: Re: [TenTec] Airpax circuit breaker for Orion
>I am running both a Paragon II and Omni 6 plus. Wonder what is the most
> likely source of parasitic ocillations in these rigs?
> ----- Original Message -----
> From: "Carl Moreschi" <>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Saturday, December 03, 2005 5:38 AM
> Subject: Re: [TenTec] Airpax circuit breaker for Orion
>
>
>> The Orion, Jupiter, Omni VI, Omni V, and Paragons also have a current
>> sensing device that will reduce drive power if the collector current is
>> above 22 amps. This covers all the situations except parasitic
>> oscillation.
>> Parasitic oscillation is the only reason for using a breaker in these
>> radios
>> because the collector current can go very high without any drive.
>>
>> Carl Moreschi N4PY
>> Franklinton, NC
>> ----- Original Message -----
>> From: "Robert & Linda McGraw K4TAX" <RMcGraw@Blomand.Net>
>> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
>> Sent: Friday, December 02, 2005 11:23 PM
>> Subject: Re: [TenTec] Airpax circuit breaker for Orion
>>
>>
>>> Quoted from the Omni VI Plus manual.
>>>
>>> "NOTE: When operating the transmitter into an SWR higher than 2:1,
>>> adjust
>>> the RF "PWR" control to a collector (Ic) current not to exceed 20 amps
>>> as
>>> indicated on the front panel meter."
>>>
>>> Now with that said, in looking at my Omni VI Plus operation into various
>>> load conditions, I find that a 1:1 SWR and 90 watts output, the Ic
>>> current
>>> is ~14 amps. With a 100 ohm load, thus a 2:1 SWR the Ic is ~12 amps and
>>> power output is 90 watts. With a 25 ohm load, thus a 2:1 SWR the Ic is
>>> ~
>> 18
>>> amps and power output is still 90 watts. The point being a 2:1 SWR does
>> not
>>> tell you if you have a 100 ohm load or a 25 ohm load. In my case, if
>>> the
>>> load gets down to 12 ohms the Ic is 20+ amps and power output is still
>>> 90
>>> watts On the other side of the slope with a 200 ohm load, the SWR is
>>> 4:1
>>> and power output is still 90 watts bit Ic is now only 10 amps.
>>>
>>> Thus using a supply with unlimited current above 20 amps can be
>>> dangerous
>>> unless you know your load Z and can control the power to such extent as
>> not
>>> to exceed 20 amps Ic. It must be done either manually or automatically
>>> by
>>> the power supply or some other fast acting current interrupt device.
>>> Failure to do this will cause excessive investment in output
>>> transistors.
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>>
>>> ----- Original Message -----
>>> From: "Vic Klein" <vhklein@ptd.net>
>>> To: <tentec@contesting.com>
>>> Sent: Friday, December 02, 2005 9:48 PM
>>> Subject: Re: [TenTec] Airpax circuit breaker for Orion
>>>
>>>
>>> > Ten Tec design philosophy for radio finals is to run them full power
>> into
>>> > any load, rather than folding back the power as SWR increases. The
>>> > only
>>> > potential for damage then is if the finals draw too much current, so
>> their
>>> > power supplies feature a current limit that protects the transistors.
>> When
>>> > using another brand of supply, then, it is just a safety measure to
>>> > include
>>> > a fast acting breaker to do what TT supplies provide internally.
>>> >
>>> > =Vic=
>>> > WA4THR
>>>
>>> --------------------------------------------------------------------------
>> --
>>> > ---------------------
>>> > To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
>>> > Subject: Re: [TenTec] Airpax circuit breaker for Orion
>>> > From: "ROBERT CARROLL" <w2wg@comcast.net>
>>> > Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
>>> > Date: Fri, 2 Dec 2005 13:03:00 -0500
>>> > List-post: <mailto:tentec@contesting.com>
>>> >
>>> > I missed some of the earlier messages on the Orion Airpax issue. Is
>>> > the
>>> > Orion or Ten Tec rigs in general more susceptible to whatever fault
>> causes
>>> > the problem? I suppose ignorance may be temporary bliss, but being in
>>> > that
>>> > state I have been running all my rigs from various Astron
>>> > supplies--with
>>> > appropriate caution about the Astron grounds.
>>> >
>>> > What causes the Orion to inhale current, what specific Airpax is
>>> > appropriate, and about how much do they go for?
>>> >
>>> > Bob W2WG
>>> >
>>> >
>>> >
>>> >
>>> > _______________________________________________
>>> > TenTec mailing list
>>> > TenTec@contesting.com
>>> > http://lists.contesting.com/mailman/listinfo/tentec
>>> >
>>>
>>>
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>> _______________________________________________
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>>
>>
>
>
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