[Elecraft] Product Suggestion - 500W Dummy Load

[Wes (N7WS)]

The power limit for most hams and ham bands is 1.5 KW PEP output. The rules 
don't state where the output is measured.  I assume it's at the antenna since 
the transmission line is part of my transmitter's matching system.  With lossy 
lines, 2.5 KW at the line input doesn't seem unreasonable.

On 9/18/2015 1:10 PM, Bob McGraw - K4TAX wrote:
> Who runs 2.5K ?   Uh, isn't that just a wee bit over the legal limit?
>
> 73
> Bob, K4TAX
> K3S s/n 10,163
>
> On 9/18/2015 1:54 PM, mfsj wrote:
>> I can tell you this there is a world of difference between 800w and 2.5k or 
>> even 1.5k for that matter. I am in 0 land and very hard to break the coasts 
>> on a good day at times so a little extra helps break those pile ups.
>> Fred  N0AZZ
>>
>>
>> Sent via the Samsung Galaxy S6 edge+, an AT&T 4G LTE smartphone-------- 
>> Original message --------From: ae4pb at carolinaheli.com Date: 09/18/2015  1:16 
>> PM  (GMT-06:00) To: 'Edward R Cole' <kl7uw at acsalaska.net>, 
>> Elecraft at mailman.qth.net Subject: Re: [Elecraft] Product Suggestion - 500W 
>> Dummy Load
>> Forgive me in advance if this is a stupid question.
>>
>> Is there any reason you have to tune at full power? It seems to me that
>> tuning can be accomplished easily with much lower power. The same thing goes
>> for the ATU to the antenna. I don't see why we need more than a few MW at
>> most for the ATU to Antenna link.
>>
>>
>>
>> Rightly or wrongly when I was in the hobby the first time I ran a TS-850
>> into an SB-220 to an MFJ roller tuner connected to an antenna switch
>> feeding: 80m inverted V, 30m/40m rotatable dipoles, and a triband beam.
>> Whenever I tuned on the inverted V or outer band limits of where my antennas
>> where tuned I ended up putting labels on the ATU on cap position and a
>> number/clock combo that represented a roller inductor position for each band
>> area I cared about. It ended up I rarely had to tune up anything one the air
>> because I knew where the antenna tuning was using just the Rig and ATU;
>> tuned the APM into a paintcan MFJ load then switch it inline. I was all set
>> and never had issues when I needed to kick in the horses.
>>
>> Now my debate is 500w vs 800w... there's a larger difference between 500w
>> and 800w than between 800w and 2.5kw signal wise if I understand
>> correctly...
>>
>>
>> Jerry Moore
>> AE4PB, K3S - S.N. 010324
>>
>>
>>
>> -----Original Message-----
>> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Edward
>> R Cole
>> Sent: Friday, September 18, 2015 2:00 PM
>> To: Elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] Product Suggestion - 500W Dummy Load
>>
>> Don't have much to say:
>>
>> Had a Cantenna from Heath in the 60's - knocked over; spilt mineral oil on
>> the floor, threw can away!
>>
>> I have acquired "dry" loads over the years rated into UHF and sometimes to
>> mw at flea markets and swaps.  My highest power load is 500w Sierra with
>> power meter and switch for 150 or 500w (probably good to 1000-MHz).  Have a
>> couple Bird terminations rated 50w.  Most can handled double their rating
>> for short duration.
>>
>> The hardest duty on my loads is when optimizing the output of a new unit
>> where I'm keyed up longer than I should.
>>
>> But I do have a question on how adjusting a tuner into a 50-ohm load saves
>> one from transmitting a signal once the tuner is connected to an antenna
>> that may not be 50-ohms.  On 600m my inverted-L is Z = 0.8
>> +j680.  Tuning into a 50-ohm load does nothing to help match the
>> antenna.  The amplifier is solid state with input and output transformers
>> (no adjustment).
>>
>> I think, unless you use a high power tetrode or triode, that no one tunes
>> amplifiers anymore.  Solid state amps are broadband and need LP filters to
>> keep from amplifying harmonics.  BTW my 2m-8877 is capable of 2000w* RF
>> output so pretty hard to find a dummy load to take that. Fortunately the
>> amp does not change much so very little tuning is ever needed (of course I
>> am on a small segment of one band about 200-KHz wide).  Of course the answer
>> is to tune antenna at lower power and hope the High Power amp will always be
>> looking at 50-ohms.
>>
>> I do not have a QRO 2m antenna tuner but the antenna SWR < 1.25 so only the
>> anode tuning needs a light adjustment occasionally (loading has not be
>> adjusted for 8 years).  My "dummy load" has 19.2 dBd gain and radiates well.
>>
>> *I operate at 1365w CW which allows for about 9% variance in meter accuracy
>> to stay legal.
>>
>> 73, Ed - KL7UW
>> http://www.kl7uw.com
>>       "Kits made by KL7UW"
>> Dubus Mag business:
>>       dubususa at gmail.com
>>