[Amps] What Do you think?

[Clark Turner]

We really need pictures of the amp. But at $900. Its almost a safe bet. 
The 3-1000 is the superior tube for ham radio use and will work at those 
lower voltages. The 4-1000s will require more voltage than 3500 if in GG 
and the trouble is that most tubes are soft BC pulls.  I have run 
4-1000s up to 12KV in GG.  I recently found a deal of a life time on two 
new 3-1000Z tubes and installed those in the amp with tuned input for 10 
to 80. I changed the power supply over to deliver a max of 6000 volts. 
My amp has a PWD 2 amp hypersil transformer.  The amp runs nicely and is 
very clean.  It does make alot of heat though. The amp will run 1500 out 
on all bands with just 40 watts drive. I typically run about 4000 volts. 
I get 3300 out with 100 watts drive, 5KW out with 150 watts drive. At 
that point, I am past tube current ratings and did not drive higher.  I 
enjoy legal limit AM and this amp is happy to do it.  If the amp has 
3-1000s $900 is a steal.


C


On 9/8/2016 2:44 PM, Bill Turner wrote:
> Something is wrong with the numbers. 3500 V at 500 mA is 1750 watts DC
> input. If you were measuring 1500 watts RF output, that would be an
> efficiency of about 86%, which is impossible with a class AB linear
> and highly unlikely even if operated class C.
>
> I would recheck the meter calibration before buying.
>
> 73, Bill W6WRT
>
>
> ------------ ORIGINAL MESSAGE ------------(may be snipped)
>
> On Thu, 8 Sep 2016 18:43:45 +0000, you wrote:
>
>> I'm interested in buying a home built amp using two 3-1000 (or 4-1000 i dont remember which). I had the opportunity to try it. HV is at 3500 volt under load, and the Ip meter goes to 1 amp,  I drove it to about 500 ma
>>
>> It displayed over 1500 watts on a bird 4410 meter into a tri band antenna with no surprises. it just sat there looking good. This thing appears to be well built. it covers 10 thru 80 meters
>>
>> The power supply (full wave with two big oil caps) with blower is in a separate cabinet under the RF deck. Its similar to the older Henry amps. And very quiet. The only thing I wasn't ready for is the amount of heat it gave off WHEW! The guy is asking $900
>>
>> What do you all think?
>>
>> Arnie
>>
>> Kd6cz
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