[Elecraft] HF amp kits

[David Wilburn]

 From the general class question pool.

G1F02 (B) [97.315a]
Without a grant of FCC certification, how many external RF
amplifiers of a given design capable of operation below 144
MHz may you build or modify in one calendar year?
A.   None
B.   1
C.   5
D.   10


Here is the ARRL link to the question pool.
http://www.arrl.org/arrlvec/el3-release-12-1-03.txt

David Wilburn
dave.wilburn at verizon.net
K4DGW
K2 #5982


Jozef Hand-Boniakowski wrote:
> I have been a ham for 43 plus years (12/23/63) and up to now have not 
> heard of any such limitation.
> 
> Jozef WB2MIC
> 
> David Wilburn wrote:
>> Just working from memory here, but wasn't there also a limit that the 
>> amateur could only build one such amp a year?
>>
>> David Wilburn
>> dave.wilburn at verizon.net
>> K4DGW
>> K2 #5982
>>
>>
>> Jim Wiley wrote:
>>> The 15 db rule applies only to manufactured for sale amplifiers.  It 
>>> does not apply to amplifiers that an individual ham builds for him or 
>>> herself, particularly when a a kit is not involved..  Section 97.317 
>>> of the rules, which is where the 15  db rule appears, applies to the 
>>> certification of external RF power amplifiers that a manufacturer 
>>> offers for sale.  Home-made amplifiers do not require certification.  
>>> They must still meet some standards, such as those involving purity 
>>> of emissions (harmonics, for example) and of course must not be 
>>> operated above 1500 watts PEP, but that's pretty much it.
>>>
>>> I am unsure of how the rule applies to kits, but I think they would 
>>> be considered a "manufactured product" if all the parts needed to 
>>> complete the amplifier are contained, in the kit.  If, however, a 
>>> "kit" contained only some of the parts, and could not in itself be 
>>> assembled into a working amplifier without adding extra parts, then 
>>> the certification rule probably  would not apply.
>>>
>>> It would be perfectly legal for a ham to build a home-brew 
>>> grid-driven amplifier that  could take  the 10 watt signal from his 
>>> K2 and boost it  to 1500 watts output.  Such an amplifier would have 
>>> (roughly) 22 db of gain.   A pair of 4CX800 tubes could accomplish 
>>> this, I think.   Remember also that the old Johnson Thunderbolt could 
>>> be operated in grid-driven mode, and it had (still has, if you can 
>>> find one) similar performance, using a pair of 4-400 tubes.
>>>
>>>
>>> - Jim, KL7CC
>>>
>>>
>>>
>>>
>>>>
>>>>> Chris Kantarjiev wrote:
>>>>>
>>>>>>
>>>>>> The Linear Amp kits seem to need a fair amount of drive. I've been
>>>>>> idly thinking about a linear that would allow me to drive it with
>>>>>> my barefoot K2 and get 600-800 watts out for CW.
>>>>>
>>>>
>>>> The limit is 15 dB and is still in the requirements despite the  
>>>> recent loosening of Part 97.  That should give something over 400  
>>>> watts when driven by a K2. I don't recall whether the "easily- 
>>>> modifiable" rule is still there, so it may be possible to have an 
>>>> amp  with an attenuator on the front-end (I heard that one of the 
>>>> Tokyo  High Power amps does this, but haven't verified that).
>>>>
>>>> 73, Bob N7XY
>>>>
>>>>
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>