SWR and ALC monitoring. Tentec does not use a circuit to measure emitter
current. They do not use current "fold back" as found in other
manufacturers of equipment. Tentec reduces drive to control PA and driver
current.
73
Bob, K4TAX
----- Original Message -----
From: "Denton" <denton@oregontrail.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, November 28, 2005 8:19 PM
Subject: Re: [TenTec] Comments on "Repairs"
>I ordered and used the specified Airpax circut breakers....they didn't make
> much difference. Until I got this Omni 6, any rig running off of the
> previous common power supply ran nicely...no final blow ups..and I had
> have
> various TT's..580 Delta, Corsair II, Paragon II, Pegasus, Yeasu FT 990 and
> an Icom 718. No problems til the Omni 6 came along.
> Wonder what the Orion has for final protection?
> ----- Original Message -----
> From: "Mike Hyder -N4NT-" <n4nt_m_o_hyder@charter.net>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Monday, November 28, 2005 5:30 PM
> Subject: Re: [TenTec] Comments on "Repairs"
>
>
>> Larry, when you ask for suggestions, I respectfully suggest you not
>> dismiss
>> them out of hand.
>>
>> Robert K4TAX said, ">Is the power supply negative connected to chassis of
>> the power supply? Some
>>>power supplies {name with held} float the negative and are prone to RF
>>>getting into the voltage sense circuit and allowing an oscillation to
>>>take
>>>place in the supply. Can spell trouble for the radio.
>>
>> The offending power supplies are Astron RS-35 I don't withhold names.
>>
>> 73, Mike N4NT
>>
>> ----- Original Message -----
>> From: "Larry DiGioia" <listacct@longwire.com>
>> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
>> Sent: Monday, November 28, 2005 7:42 PM
>> Subject: Re: [TenTec] Comments on "Repairs"
>>
>>
>> Since you guys were kind enough to give me multiple replies, I am going
>> to reply to all messages at once:
>>
>> Robert & Linda McGraw K4TAX wrote:
>>
>>>Here goes........have patience with my probing.
>>>
>>>What type of power supply you using?
>>>
>> Astron RM-35M rack mount set to exactly 13.8VDC per another long-time
>> Omni owner.
>>
>>>Is the power supply negative connected to the chassis of the Omni via a
>>>separate ground and not just the negative power lead? It should be.
>>>
>>>
>> Not exactly, but both are connected to a 2" copper ground bus bar using
>> 1" braid, only 2 to 3 feet.
>>
>>>Is the power supply negative connected to chassis of the power supply?
>>>Some
>>>power supplies {name with held} float the negative and are prone to RF
>>>getting into the voltage sense circuit and allowing an oscillation to
>>>take
>>>place in the supply. Can spell trouble for the radio.
>>>
>>>
>> Well, I just ran all weekend with my standby Yaesu radio connected to
>> the same PS. This is also the same PS, set up the same way, that I have
>> been running since 1998.
>>
>>>Are all pieces of station equipment connected together back to a common
>>>point such as the power supply via separate dedicated ground cables.
>>>Should be.
>>>
>>>
>> All equipment goes (via copper braid or copper strap) to the bus bar,
>> which is connected via copper strap to a ground rod just outside.
>> Maximum distance between equipment is maybe 4 feet.
>>
>>>Regarding the tuner, do you use the radio to adjust the match or do you
>>>have
>>>a bridge like and Autec or MFJ to set the match?
>>>
>>>
>> {The best antenna tuner that money can buy, used incorrectly, is no
>> better than a cheap tuner.}
>>
>> The tuners are a Nye Viking and a Palstar BT1500. I use my MFJ tester to
>> determine whether operation is even possible on bands/antennas, then
>> tune up again with the radios at 5 watts or so and gradually increase
>> power. I made a table of all possible bands/settings which I keep on the
>> wall, and use as a starting point. When it's time to switch bands, I
>> gradually inch up the power as before, but all that's usually needed are
>> minor touch-ups.
>>
>>>Is the meter used to measure SWR in the tuner, or an external meter, or
>>>the
>>>one in the radio. Coax cables between the devices can cause the SWR to
>>>look
>>>good at one place and produce a very poor match at another location in
>>>the
>>>system. This can be due to a bad cable or poor connector installation or
>>>loose connector on the SO-239.
>>>
>>>
>> I used a Drake external meter for the first 5 years or so with my
>> home-made tuners, then after switching to the two commercial ones, I use
>> their internals. There are a few coax switches, though... there are a
>> couple of 3-foot and a couple of 6-foot "jumpers" altogether, all
>> commercially-made RG213.
>>
>>>In my case I use a 238 tuner with its internal SWR/Power meter, a Daiwa
>>>CN-801 SWR & Power meter, and the SWR meter in the radio. In adjusting
>>>the
>>>tuner I switch in and use an MFJ antenna bridge. Then switch the radio
>>>into
>>>the system. In all cases, with power, all three SWR indicating devices
>>>will
>>>show the same and correct SWR reading. I have seen installations where
>>>SWR
>>>at 3 places will be different. This indicates circulating RF and that
>>>can
>>>give false SWR indications. Hope you don't have this condition.
>>>
>>>
>> Well, with two balanced lines leading into the shack, "circulating RF"
>> is pretty normal here. But also note, that the last two times this radio
>> gave out, it was while advancing the power on 20m (coincidence?) and I
>> barely made it past 10 watts or so when it blew. Once into my Hy-Tower
>> and another time into a (balanced) dipole.
>>
>>>Parts for the Omni VI and VI Plus are basically "off the shelf" parts.
>>>Be
>>>assured that Tentec Service is fixing the radio, taking it through a 24
>>>hr
>>>burn-in and it is working when it gets to you. Hate to say it, but
>>>something in your station or your method of tune-up is causing a problem.
>>>
>> I won't argue that. For a while I thought it was a cheapo coaxial
>> lightning arrestor (the arc-plug type.) Then I went to having all
>> suppression outside the house, via Polyphaser for coax and Wireman
>> spark-plug gadgets for the balanced ones.
>>
>> I'm with you on the PS issues, but will wait to hear more. Thanks!
>>
>> Jeff Frank wrote:
>>
>>>I had a problem with my Omni Six where the radio had to be returned to
>>>TenTec four times and each time something else would go wrong.
>>>Eventually,
>>>the radio was fixed and the folks at Tentec remained as helpful as they
>>>could be. After the first two times TenTec paid all the shipping and
>>>didn't
>>>charge me for their work.
>>>
>> Same here! I do appreciate it, and I know they are trying.
>>
>>> In my experience they will do the right thing. Don't give up.
>>>
>> Thanks for the encouragement! Well, it's kind of self-evident here on
>> the list: a half-dozen guys who had similar problems, and they are all
>> still Ten-Tec owners, if not evangelists...
>>
>> Denton wrote:
>>
>>> Larry, the same thing happend to my Omni VI.....went back 3 times to
>>> have both the finals and final driver transistors replaced.
>>
>> I am pretty sure they never replaced the actual finals, it has always
>> been smaller components.
>>
>>> In my case, I was running the rig and another hf rig at the same time
>>> on a common power supply...on different bands and different antennas.
>>
>> Not here, although I have a spare rig now, I have never transmitted on
>> both at the same time.
>>
>>> Right now, I am running separate power supplies, Ten Tec model 961,
>>> one per hf rig....otherwise same antenna tuners and same antennas as
>>> before. So far, fingers crossed.
>>> I will never be too sure what caused the finals to blow...but I think
>>> that rf was getting into the final brick via the power supply positive
>>> lead.
>>
>> Well, I would be willing to switch power supplies if I thought it would
>> cure it, but remember, the same one ran it for 5 years with no problem.
>> Based on what I am hearing, I think I will stock up on more ferrite cord
>> clamps... but there is already one on the supply lead just outside the
>> radio.
>>
>>>Those are the classic symptoms of a parasitic oscillation. You probably
>>>already know this. But in any case, you need to look at suppression and
>>>low
>>>pass (HF) filters in the rest of the path to see if you can break up the
>>>oscillation.
>>>
>>>73 de Gary, AA2IZ
>>>
>> Yes, I agree, but as to the cause, I am lost. I had a low-pass filter
>> for TVI purposes previously, took it out a while back because we went to
>> satellite, hmmm, timing is right... thanks.
>>
>>> Larry....do you notice the same behavior while transmitting into a
>>> good dummy load or does the problem surface only when transmitting
>>> thru your tuner into your antenna???
>>>
>>> 73, Joe W2KJ
>>
>> Well, first, I don't own a dummy load, I think they are useful for
>> tuning "tuneable" transmitters, but on a solid-state final, I don't see
>> it. As for "the problem surfacing," when it does, I am dead in the water
>> and the rig goes back to Tennessee, last time it was dimming the lights
>> on transmit...
>>
>>>Your PA is drawing too much current for whatever reason. Use a TT 961 PS
>>>to
>>>protect the PA or put a similar "fast cycle" 22 Amp breaker in line.
>>>
>>>I've been running either an Omni D, Paragon II, Corsair II, or OMNI VI+
>>>for over 25 years. I always used a matching TT power supply and never
>>>had
>>>a PA problem although the PS circuit breaker "popped" many times when I
>>>made a mistake on tune up.
>>>
>> This really fits. My present PS is way over-rated at 35A, so I am going
>> to seriously consider this. Thanks!
>>
>> Lyle Dunlap wrote:
>>
>>>Your getting some good advice Gary I would just add a couple of things.
>>>Get
>>>a 20 AMP Air Pax ckt bkr. years ago one could get them from TT but maybe
>>>not
>>>today.
>>>
>>>
>> I would love to find one, I will keep this in mind if I don't go with
>> the 961.
>>
>>>Another thing if you do not use some device such as an ant. analyzer then
>>>at
>>>least tune up on a duty cycle. IE: a keyer on fast dits, if nothing
>>>else.
>>>I hear a lot of steady key down tuning these days, even tubes dont like
>>>that.
>>>
>>>
>> I already made a resolution to do this after getting the new tuners. The
>> Nye will not tolerate it, the metering is very strange, it has some kind
>> of a delay in it.
>>
>>>That fast acting ckt bkr will keep you out of trouble even if you dont
>>>know
>>>what your doing. Not to imply you dont.
>>>
>> No offense taken. When chasing DX I sometimes get emotional and
>> heavy-handed. I also should mention that I run PSK. When I can. But I
>> was always remembering the ads for the Omni, talking about how the final
>> would "automatically fold back the power when necessary," and for years,
>> it did.
>>
>>>I've had similar experiences (current jumping up all of a sudden because
>>>of
>>>self-oscillation) with the older Ten-Tec radios. In my case the trouble
>>>was
>>>caused by the rig's not producing ALC voltage because of bad diodes. I
>>>called Garland and he said something like, "Yep, they can do that if the
>>>diodes are bad." It cost me about $0.96 to make the repair.
>>>
>>>73, Mike N4NT
>>>
>> That's what they replaced last time. But for me, when it happens, it
>> self-destructs and never "comes back."
>>
>>
>>
>> --
>> Larry N8KU
>>
>> w w w . l o n g w i r e . c o m
>> 100% CW 100% HF
>>
>> _______________________________________________
>> 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
>>
>
>
> _______________________________________________
> 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
|