Gary,
That's the whole point. An amateur amp ought to be designed so it gets maximum
power transfer too! It's kinda bad that the 11 meter guys did it and a lot of
amateur amp manufacturers were too tight to do it. One thing, this cant be said
about Heathkit, they did add them and a very few others.
Best,
Wil
*********** REPLY SEPARATOR ***********
On 3/29/05 at 11:26 AM Gary Schafer wrote:
>I don't think most 11 meter amp manufacturers are to concerned about
>inter mod. The tuned circuit is there to transfer maximum power from the
>50 ohm radio.
>
>73
>Gary K4FMX
>
>
>Will Matney wrote:
>> Tony,
>>
>> Even the old 10-11 meter sweep tube amps had a tuned input, or at least
>the better ones of them. They even knew it was better than not having any
>at all. Most of those used a tuned transformer feeding either the
>cathode(s) or the grid(s). Same thing applies to any amp IMHO.
>>
>> Best,
>>
>> Will
>>
>> *********** REPLY SEPARATOR ***********
>>
>> On 3/28/05 at 10:57 PM Tony King - W4ZT wrote:
>>
>>
>>>Tomm Aldridge wrote:
>>>
>>>
>>>>This is an interesting thread to me not because of the AL-811 vs
>>>>MLA-2500 but because I am designing and building an amp. If I
>>>>understand this correctly, using a TS570 transceiver to drive my amp
>>>>implies I really don't need a tuned input circuit as I can just use the
>>>>built-in tuner of my rig to achieve a good enough match to the input of
>>>>the tubes. That saves me money and complexity.
>>>>
>>>>However, some on this list advise that the proximity of the output C of
>>>>the tuned input to the cathode of the PA is very important for its
>>>>"flywheel" or energy storage effect during the wide swings in impedance
>>>>during a cycle of operation.
>>>
>>>I have gotten the same advice / impressions. A tuned input adjacent to
>>>the cathode appears to be the only true way to get a good flywheel
>>>effect. I suppose, if you didn't care about improving the IMD that it
>>>might not matter. I hope that some of the experts will chime in on
>this.
>>>
>>>
>>>>My question is, which strategy should one employ and what are teh pros
>>>>and cons? Assuming, of course, a built in AT such as in the TS570.
>>>
>>>There is a good link at <http://www.somis.org/SB220ci.html> where Rich
>>>discusses the need for a good tuned input. This article is about the
>>>SB-220 but the idea is the same. Go to the link and scroll down to
>>>"Improving Input SWR" about two thirds of the way down. I think that
>>>will help us understand why it's more complex than matching the radio
>>>output to the cathode input.
>>>
>>>My questions to the group are these:
>>>How many of those running homebrew amps use a tuned input? How many are
>>>not?
>>>Now how many of those running a COMMERCIALLY manufactured amp are NOT
>>>running a tuned input?
>>>
>>>
>>>>Regards,
>>>>
>>>>KD7QAE
>>>>Tomm
>>>><snip>
>>>
>>>73, Tony W4ZT
>>>
>>>_______________________________________________
>>>Amps mailing list
>>>Amps@contesting.com
>>>http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|