I guess that means my tubes should last much longer... I only wish I could
operate 3 hours a day!! Of course someone has to contribute to the Social
Security and Medicare plans. :-(
Good info Bob.
73
-Eric
W9WLW
> On Aug 11, 2014, at 8:00 PM, "Bob McGraw - K4TAX" <RMcGraw@Blomand.net> wrote:
>
> Based on typical usage of 3 hrs per day for 5 days per week this is 15 hrs
> per week. The in 52 weeks this is 780 hours per year. With a tube expected
> life of 20,000 hours, that equates to some 26 years of tube life.
>
> Of course someone asked me recently what I thought the average transmitting
> tube life would be. I responded "depends on how many times they are abused".
>
> Exceed grid current maximum = abused.
> Exceed plate current maximum = abused.
> Flashover in the PA circuit = abused.
>
> In a properly designed and tuned amp none of the above should ever occur.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- From: "Wade Staggs" <tvman1954@gmail.com>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Sunday, August 10, 2014 12:54 PM
> Subject: Re: [TenTec] Hercules 444 amp
>
>
>> *At least for now, even if we could afford one of the Big Gun Solid State
>> Amps. I would hope that we would have the good sense to stick with an Amp
>> which runs 1 or 2 of the 3-500ZG Triodes. They are as tough as Nails. How
>> can you argue with a system that with proper care, will run a lifetime. The
>> tubes in our SB-220 are Original. This means that they are approaching
>> their Fortieth Birthday. We recently replaced the Capacitors and Relay. The
>> Amp was still working Great when we did this Preventative Maintenance. And
>> Even a Cave Man with Knives and Bear Skins can repair the Amp if needed. *
>> * 73
>> from Wade/KJ4WS*
>>
>>
>>> On Sun, Aug 10, 2014 at 12:01 PM, Robert <rmcgraw@blomand.net> wrote:
>>>
>>> Many to most design parameters do change radically when converting from
>>> BIPOLAR to MOSFET devices.
>>>
>>> I seen to think MFJ does have their products in the reach of the average
>>> ham. I find typically they offer reasonable designs, reasonable quality at
>>> reasonable prices. Maybe it's the hams average reach that needs adjusting.
>>> The days of the SB-200 and SB-220 KIT prices are long gone.
>>>
>>> Good quality amps, those that are clean and don't spew garbage across the
>>> bands, require good design and good quality parts. Then add a high duty
>>> cycle and it places more demand on the designs and the parts choices.
>>>
>>> 73
>>> Bob K4TAX
>>>
>>> Sent from my iPhone
>>>
>>> > On Aug 9, 2014, at 5:38 PM, Brian Carling <bcarling@cfl.rr.com> wrote:
>>> >
>>> > So maybe the Hercules can be converted to use MOSFETs. Seems like it
>>> should be possible.
>>> >
>>> > I also think MFJ needs some competition on MOSFET linear amplifiers to
>>> get the price point within reach of the average ham.
>>> >
>>> > There is just not a good reason why so many linear amplifiers should
>>> cost $3500 to $9500 when you look at the parts cost and manufacturing cost.
>>> >
>>> > [/SOAPBOX]
>>> >
>>> > Best regards - Bry Carling
>>> >
>>> >
>>> >
>>> >> On Aug 9, 2014, at 5:24 PM, Douglas <sparks06524@yahoo.com> wrote:
>>> >>
>>> >>
>>> >> Date: Sat, 9 Aug 2014 10:12:45 -0400
>>> >> From: Brian Carling <bcarling@cfl.rr.com>
>>> >> To: "k9yc@arrl.net" <k9yc@arrl.net>,
>>> >> Discussion of Ten-Tec Equipment
>>> >> <tentec@contesting.com>
>>> >> Subject: Re: [TenTec] Hercules 444 amp
>>> >> Message-ID: <86F80EE5-1044-42AA-9641-D8859123467B@cfl.rr.com>
>>> >> Content-Type: text/plain;
>>> >> charset=us-ascii
>>> >>
>>> >> Seems like a lot of RF power transistors are similar, so it
>>> >> should not be too difficult to find a substitute.
>>> >>
>>> >> Best regards - Bry Carling
>>> >>
>>> >> ------------------------------------------------------------
>>> >>
>>> >> Ah - but it is hard to find a substitute. The Ten-Tec factory can't
>>> find one.
>>> >>
>>> >> There were only a few designs of 250 to 300 watt 50V bi-polar power
>>> transistors made. The remaining ones are hard to get and have an HFE that
>>> is too high. Several such transistors have been totally discontinued.
>>> Motorola for example is out of that business. M/AComm bought some of their
>>> designs but in general bi-polar RF transistors are considered passe. RF
>>> MOSFETS are now the name of the game.
>>> >>
>>> >> Per another poster: I've not had trouble with the power supply >>
>>> >> drifting
>>> upward with temperature rise. Perhaps they solved that with compensation.
>>> >>
>>> >> 73,
>>> >>
>>> >> Doug/WA1TUT
>>> > _______________________________________________
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