[Elecraft] Product Suggestion - 500W Dummy Load

Fri Sep 18 16:10:22 EDT 2015

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
>
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