Hi Steve,
Sounds like I was well within the device specs at Tsink = +70 C (implies a
Tj of around 120 deg C assuming Pd = 50W). This would data tend to confirm
Ten-Tec's claim of 100% duty cycle capability. A better test would be to
let the rig run longer until thermal equilibrium is reached. The derating
figure would imply a Tjmax = 200 deg C. I this stated explicitly in the data
sheet? If so, you could probably safely run the heat sink to upwards of +100
deg C (assuming nothing else besides the finals that is attached to it would
be damaged).
Thanks for the info.
Mike, W4EF..........
----------
From: Steve Baron[SMTP:stevebaron@starlinx.com]
Sent: Wednesday, March 03, 1999 1:29 PM
To: Michael Tope; 'promedia'
Cc: 'Ten-Tec'
Subject: Re: [TenTec] Paragon
Did a web search and found two places that had them One wanted abt 150 for
a pair. RFPARTS wa much cheaper.
Just happened to have a copy of an old RF Data Manual! Was gong to throw it
out a few months ago.
Total device dissipation at 25 deg C is 175 W. Derate one Watt per degree
above 25 deg C.
Thermal resistance - junction to case - is 1 deg C per Watt.
-----Original Message-----
From: Michael Tope <W4EF@pacbell.net>
To: 'promedia' <promedia@itnet.com.pl>
Cc: 'Ten-Tec' <tentec@contesting.com>
To: <tentec@contesting.com>
Date: Wednesday, March 03, 1999 1:03 PM
Subject: RE: [TenTec] Paragon
>
>Alec,
>
>Finally got around to making some preliminary measurements on my
>Paragon's heat sink temperature. The following data was taken
>from my Paragon 585 running key down as noted with no cooling
>fan. As you can see the sink heats up rather quickly at 100%
>duty cycle - 8 minutes to go from room temp (25 deg C) to +70 deg C
>(160 deg F). At this point (t=+8 minutes), I switched to a 50% duty
>cycle (1 minute TX/1minute Rx), and the temperature stabilized at
>~69 deg C. Tx collector current was maintained around 20 amps which
>corresponds to ~90 watts RF output. Cool down appears to be rather
>slow (10 minutes = 25 deg C), but am sure that a small cooling fan
>would improve things drastically. I should note that I had to manually
>back off the RF drive to keep the Paragon's internal 25 amp fuse from
>blowing, as the collector current tends to increase significantly with
>device temperature.
>
>Do you have a transistor data sheet for the MRF458? I was wondering
>what the thermal resistance (junction-to-case) and Tjmax is for this
>device. BTW, you appear to be correct that this transistor is no longer
>in production - I couldn't find it on the Motorola website.
>
>Cheers,
>
>Mike, W4EF..................
>
>Elapsed Heat Sink
>Time Temperature
>(min) (deg F) (Deg C)
>0:00 77.6 25.33 Ic=20 amps
>0:01 83.8 28.78 Ic=20 amps Had to backoff drive to
> maintain constant Ic
>0:02 95.9 35.50 Ic=20 amps " "
>0:03 109.1 42.83 Ic=20 amps " "
>0:04 120.8 49.33 Ic=20 amps Ic starting to stabilize
>0:05 131.8 55.44 Ic=20 amps
>0:06 141.2 60.67 Ic=20 amps
>0:07 150.2 65.67 Ic=21 amps Same drive setting
>0:08 157.8 69.89
>
>0:08 160.4 71.33 Turned Off Tx
>0:09 156.8 69.33 Tx On
>0:10 156.8 69.33 Tx Off
>0:11 155.2 68.44 Tx On
>0:12 156.2 69.00 Tx Off
>0:13 155.7 68.72 Tx Off
>0:14 149.8 65.44 Tx Off
>0:15 143.7 62.06 Tx Off
>0:16 138.5 59.17 Tx Off
>0:17 133.4 56.33 Tx Off
>0:18 130.8 54.89 Tx Off
>0:19 126.8 52.67 Tx Off
>0:20 123.6 50.89 Tx Off
>0:21 120.6 49.22 Tx Off
>0:23 115.6 46.44 Tx Off
>0:25 110.9 43.83 Tx Off
>
>
>
>----------
>From: promedia[SMTP:promedia@itnet.com.pl]
>Sent: Monday, January 04, 1999 10:09 AM
>To: Michael Tope; tentec@contesting.com
>Subject: [TenTec] Paragon
>
>
>Mike,
>
>you are great !! Thanks for the message and suggestions.
>
>Well, the fact is, I 'm somewhat fed up with all that.
>I have a full bag of blown transistors and, just after
>the last failure, I've encountered really big problems
>with buying the replacements as Motorola stopped
>producing them... I had enough,
>especially that ten-tec's help cost me really much
>and left in nothingness...
>
>Probably, the bias problem means there's no
>thermal compensation, as the protecting diodes
>are located in the midair actually.
>When using even the minimum power,
>with processor on (SSB) or RTTY,
>the heatsink temperature goes so high
>one couldn't believe to happen with a properly
>designed module. Probably, also, that is
>the moment the bias protection fails.
>Implementing, under such circumstances,
>a heatsink with horizontal fins,
>without a fan,
>tell me it's rethoric, calls for someone
>to be sent back to primary school lessons in phisics.
>
>Anyway, despite the fact I operated
>the paragon with my hand on the heatsink
>thus controlling the temperature, I wasn't
>able to avoid the next transistor set
>failure as well as a tremendous impact
>on my budget which followed....
>
>Since I'm running my rig barefoot,
>as it's common in this part of the world,
>factory shouldn't be surprised I want to
>get every watt out of it.
>Implementing the FSK possibility with
>this particular design seems really odd...
>As in my case, it means implementing
>instantaneous PA damage facility...
>
>Could you, please, tell me,
>how does the PA behaves in your case
>regarding its temperatures, etc ?
>
>All the happiness to you all
>for the New Year....
>
>
>Alec/SP2EWQ
>
>
>
>
>
>Michael Tope wrote:
>
>> Hi Alec,
>>
>> Sorry I have taken so long to reply, but I have thousands
>> of messages in my inbox here. Interesting problem with
>> your PA - I have a Paragon here which I have operated on and off
>> but relatively trouble free for about 7 years. The only problem
>> I had with the PA was a blown electrolytic capacitor - it went
>> off like a shotgun one evening while I was tuning up. Scared
>> the hell out of me. At first, I thought my downstairs neighbor was
>> retaliating for the loud music from my stereo - grin grin.
>> When I opened up the PA module, I found pieces of electrolytic
>> strewn all over the inside of the PA module. I promptly removed the
>> debris and replaced the blown cap with one from my junkbox. The PA
>> has worked trouble free since that time, including a little contest
>> duty and RTTY at 100 watts.
>>
>> Sounds like fundamentally you have a bias problem. Have you checked
>> the bias circuit in the PA against the schematic? Assuming your
>> circuit
>> and mine are similar, I suspect a bad component(s) as opposed to a
>> flawed design. Have you made the bias current adjustment (this is a
>> very simple procedure)? Worst case, have you considered buying a
>> new PA module.
>>
>> Don't rule out operator error either. About two years ago, I was
>> cursing
>> my Paragon to high heaven and was ready to leave it for the garbage
>> man.
>> The microprocessor kept locking up or getting into weird states where
>> the
>> QSK wouldn't work properly when running split frequency. I almost took
>>
>> a sledge hammer to it during the 96 SS CW. After several calls to
>> Ten-Tec
>> and countless hours inside the microprocessor section adding bypass
>> caps
>> and chokes, I came to my senses and measured the input voltage under
>> trasmit
>> conditions. Turns out that I was losing 2 volts across a resistive
>> fuse
>> holder. When I replaced the fuse holder, everything started working
>> perfectly. Lesson learned - don't always look for the complicated
>> solution
>> first!
>>
>> As a final note, I would suggest for your own sake to keep the
>> inflammatory
>> rhetoric to a minimum. People don't respond well to that sort of
>> thing, and
>> its usually counterproductive when it comes to solving technical
>> problems. As I
>> learned from my faulty fuse holder experience, all the cussing and
>> swearing
>> in the world didn't make my radio work properly - only careful and
>> deliberate
>> troubleshooting.
>>
>> Good Luck,
>>
>> Mike, W4EF......
>>
>> ----------
>> From: promedia[SMTP:promedia@itnet.com.pl]
>> Sent: Tuesday, December 08, 1998 12:20 PM
>> To: Michael Tope
>> Subject: Re: [TenTec] on ten-tec's primitivy...
>>
>> Hi Michael,
>>
>> thanks.
>> I'm just abt starting believing it's more my problem
>> than paragon's. Everybody's so happy...
>>
>> Since the beginning paragon delivered no more than 50W
>> output. I wouldn't care much abt it if it only stayed that way.
>> But, there must be something really fishy. I've got already
>> a full bag of burnt PA transistors which are extremely difficult
>> to buy here.
>>
>> The module was sent to ten-tec for the repairs. They kept it
>> for ages there, and sent back in the same condition.
>> As not to reach bancrupcy, I had to detach the PA.
>>
>> There were other failures in the meantime too, but I could cope
>> with them myself somehow. I think, PA is areally badly designed module
>>
>> there and using radiator with horizontally placed ribs shows
>> a kind of ignorance in basic phisics. Especially, they don't install
>> any
>>
>> fans with it.
>>
>> When it worked, I used to operate with one hand on PA radiator
>> and even that way I couldn't prevent the transistors from damage.
>>
>> I gave up, Michael.
>> I thought I was buying something America's Best.
>> I really did.
>>
>> Yours,
>>
>> Alec/SP2EWQ
>>
>> Michael Tope wrote:
>>
>> > Alex,
>> >
>> > I have only casually following this thread. I am having
>> > a hard time understanding exactly what is wrong with
>> > your Paragon. I am correct that you have a problem with
>> > the RF module? Is this low output power, intermittent
>> > operation?
>> >
>> > Just curious, I am also a Paragon owner.
>> >
>> > 73 de Mike, W4EF.......
>> >
>> > ----------
>> > From: promedia[SMTP:promedia@itnet.com.pl]
>> > Sent: Monday, December 07, 1998 10:07 AM
>> > To: pcuellar@bright.net
>> > Cc: 'seweber@netnitco.net'; tentec@contesting.com
>> > Subject: [TenTec] on ten-tec's primitivy...
>> >
>> > <<File: ATT00001.html>>
>> > Hi to all, and you Phil,
>> >
>> > Well, it seemed to me what I bought it WAS a proffessional Radio.
>> > I paid, at least, for such.
>> > I didn't want and don't want anything for free. Some of you are
>> > heavenly
>> > praising the fact
>> > you were given anything. Maybe there must be some Alexes first for
>> > some
>> > Bills, Phils
>> > and similar to exist later.
>> >
>> > What I certainly found I am talking colours to some who are
>> completely
>> >
>> > blind.
>> > You should well accept the fact, that what you get for a
>> proffesional
>> > money is a kind
>> > of an amateurish device. Designed in that manner and manufactured
>> in
>> > that mannner.
>> > It's primitivity is shown right from the front panel, through that
>> > what's inside, to the last screw
>> > supposed to keep the speaker in place, instead protruding from upper
>>
>> > cover and getting
>> > in direct conflict with the rear panel.
>> > If you cannot see well enough use a magnifying glass. And accept the
>>
>> > fact.
>> >
>> > The problem simplicity or primitivity doesn't mean a good
>> operational
>> > quality in this case.
>> > It's simple for you there, to send the rig for repairs, and get it
>> > free.
>> > And I understand why.
>> > For such a factory as ten-tec is simpler not to charge a customer
>> for
>> > the repair
>> > because he or she might ask some "trivial" questions afterwards. One
>>
>> > who's not blind might find out
>> > it was factory to blame for that what'd happened. Some might even
>> get
>> > a
>> > bit angry....
>> >
>> > Since I had enough of that ten-tec's proffesional beating around
>> > bushes,
>> > when I asked them
>> > for help, I've decided to maintain paragon's usefulness myself
>> > spending
>> > a lot on modifications.
>> > Accept the fact, too.
>> >
>> > Ten-tec must first knuckle well over their designing desks to
>> produce
>> > something up to present
>> > standards. It's going to take some time, however.
>> > I wonder if they can at all having such a "good" support on the
>> > rubbish they are
>> > filling their boxes with now.
>> > Besides, Primitivity must take its origin from somewhere, too. In
>> this
>> >
>> > case it's not so difficult
>> > to point the source.
>> >
>> > Anybody who's considering buying ten-tec's must expect and be
>> prepared
>> >
>> > for
>> > a lot contacts with ten-tec afterward his "pride and joy" will have
>> > arrived.
>> > Best you could move closer to a post office.
>> > Some will fruit with something free (shipping excluded).
>> > Remember Alec then, your sponsor...
>> >
>> > Yours, as always,
>> >
>> > Alec/SP2EWQ
>> >
>> > Phil Cuellar wrote:
>> >
>> > > >
>> > > > > {snip} Besides.
>> > > >
>> > > > >I'm not happy with the results.
>> > > >
>> > > > >With some rig really being working properly, I would have
>> > > >
>> > > > >doubled the final score, AT LEAST.
>> > > >
>> > > > >See you all..
>> > > >
>> > > > >Stay happy, but still, remember, think twice,
>> > > >
>> > > > >before you start reading ten-tec commercials.
>> > > >
>> > > > >Learn from the mistakes committed by others.
>> > > >
>> > > > >It's a part of a universal wisdom, guys...
>> > > >
>> > > > >>Alec/SP2EWQ
>> > > >
>> > > Considering his score and his feelings that he should have been
>> able
>> >
>> > > to at
>> > > least double it, maybe Alec needs a PROFESSIONAL radio, he is
>> > > obviously too
>> > > "good" an operator to use a radio designed well enough for us
>> lowly
>> > > bumbling AMATEURS! I wish him luck in his search for a better
>> radio.
>> >
>> > >
>> > > 73 de KB8TRK - Phil
>> > >
>> > > --
>> > > FAQ on WWW: http://www.contesting.com/tentecfaq.htm
>> > > Submissions: tentec@contesting.com
>> > > Administrative requests: tentec-REQUEST@contesting.com
>> > > Problems: owner-tentec@contesting.com
>> > > Search:
>> http://www.contesting.com/km9p/search.htm
>
>
>
>
>--
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>Submissions: tentec@contesting.com
>Administrative requests: tentec-REQUEST@contesting.com
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>Search: http://www.contesting.com/km9p/search.htm
>
>
>--
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>
>
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Problems: owner-tentec@contesting.com
Search: http://www.contesting.com/km9p/search.htm
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