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Author Topic: Getting Ready for 1.5KW  (Read 3650 times)
K0IZ
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Posts: 737




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« Reply #15 on: April 07, 2013, 07:08:16 AM »

Perhaps install a 30a  240 circuit, rather than 20a, less voltage drop under load, particularly if somewhat long run.  But 20a will work.  Also many dummy loads offered for sale are limited on power/duration.  I really like the Bird dummy loads.  New, they are big bucks.  But frequently available on eBay at low prices (typically under $100).  Flat SWR clear up into the GigaHz region.  A 500 watt Bird will easily handle 1.5KW out.  My 500 watt will handle 3KW for several minutes with minimal heating.
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W8JX
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Posts: 5774




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« Reply #16 on: April 07, 2013, 08:21:57 AM »

Perhaps install a 30a  240 circuit, rather than 20a, less voltage drop under load, particularly if somewhat long run.  

Maybe if it is a couple hundred feet even then. My well pump is on 170 feet of 12ga wire and takes close to 20a to start and 7a to run on 240 and been that way for 30 years and is not a problem.  240 is not like 120 on voltage drop as it takes twice the drop for same effect as on 120. Wasted money unless you are putting in a 30 amp sub panel in shack.
« Last Edit: April 07, 2013, 08:25:04 AM by W8JX » Logged

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K4RVN
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Posts: 770




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« Reply #17 on: April 07, 2013, 03:17:31 PM »

Sam, I was addressing my suggestion to W6UV, not commenting on your post. What you said is certainly good to read and be aware of for sure. What I suggested is the real world way to see if an assessment is working as perceived. One has to be aware of what's going on in the shack when the max power is used. If you were to look at my shack photos on QRZ.com you would see a field strength meter hanging on the wall. When I went from 100 watts to 1000 I had to clean up some connections as indicted by the RF floating around in the shack. I just recently had a ground loop when installing a different transceiver to an amp. I was alerted by the reading on my field strength meter, cleaned up the connections now nothing on the meter.

73
Frank
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W9KDX
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Posts: 770




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« Reply #18 on: April 07, 2013, 07:03:33 PM »

Sam, I was addressing my suggestion to W6UV, not commenting on your post. What you said is certainly good to read and be aware of for sure. What I suggested is the real world way to see if an assessment is working as perceived. One has to be aware of what's going on in the shack when the max power is used. If you were to look at my shack photos on QRZ.com you would see a field strength meter hanging on the wall. When I went from 100 watts to 1000 I had to clean up some connections as indicted by the RF floating around in the shack. I just recently had a ground loop when installing a different transceiver to an amp. I was alerted by the reading on my field strength meter, cleaned up the connections now nothing on the meter.

73
Frank

Thanks for clearing that up, Frank.  Your ideas make sense.
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Sam
W9KDX
NO9E
Member

Posts: 403




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« Reply #19 on: April 08, 2013, 12:03:15 PM »

One never knows what happens at QRO level. Try and see. It ain't good if it smokes. It is good if it does not. But very few items actually smoke.

For tuning, dummy load is not that useful if SWR is less than ideal. ACOMs have a tuning indicator that can be used at low power.  One can tune non-ACOM amp that way for a fixed amplification. For instance, if an amp amplifies 30 times (8877), 5W in should give 150W out when peaked. Requires a radio with low-power tune (e.g., K3) and digital meter like LP100. With presets and experience, tuning can be done in a second.

Ignacy, NO9E




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W8NF
Member

Posts: 53




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« Reply #20 on: April 10, 2013, 03:38:05 PM »

If you plan on using a dipole or some other antenna config from 40m down, the tuner needs to have the same rateing as the amplifier plus a little to spare.
The cost of the amplifier plus the cost of a good tuner adds up fast.
Good luck.
A lot of the "tuners" you think you hear are people pushing the "auto tune" button, right on top of a QSO, because they neglect to realize that the radio transmits, in order to tune.

Dave W8NF
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K9SRV
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Posts: 121




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« Reply #21 on: April 12, 2013, 10:00:27 AM »

extras tuning on a dx receiving frequency don't realize they are throwing a signal out?
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W8JX
Member

Posts: 5774




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« Reply #22 on: April 12, 2013, 10:42:14 AM »

extras tuning on a dx receiving frequency don't realize they are throwing a signal out?

You know funny thing about tuning amps, many seem to think you have to tune up right on exact frequency to be good when you can in fact tune 10 or 20kc away and be fine. I rarely retune when I move around in band too.
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K9SRV
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Posts: 121




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« Reply #23 on: April 13, 2013, 11:57:53 AM »

Cecil that's what gets me! I tune AT LEAST 6 kc away from the split side...
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