In the case where an amp uses 2 tubes, do replace both if there is a failure.
And I spend the extra $$ for the matched pair or quad as the case may be.
73
Bob K4TAX
Sent from my iPhone
> On Aug 10, 2014, at 2:08 PM, "Duane Calvin" <ac5aa1@gmail.com> wrote:
>
> This was certainly true of the EIMAC tubes, as long as you cared well for
> them. I've not had as good a luck with the current Chinese-sourced tubes
> (specifically, the 3-500ZG's from RF Parts, which the Centurion uses.)
>
> 73, Duane
>
> Duane Calvin, AC5AA
> Austin, Texas
> www.ac5aa.com
>
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Wade Staggs
> Sent: Sunday, August 10, 2014 12:54 PM
> To: Discussion of Ten-Tec Equipment
> 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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