I have an L7 run on 120VAC and have used it on 160M many times. I only
drive it with about 50W and it gives me about 450W out, same as the other
bands. Never had an issue and the fan doesn't even come on at that power
level. I have never run it at higher power because I don't have 220V in the
shack. The tubes are very old and predate my ownership by a great deal.
On Tue, Mar 16, 2010 at 3:41 PM, k9...@aol.com wrote:
Fellow enthusiasts,
Wonder if anybody has had bad experiences with the Drake L7 on 160
meters. I'm checking one out for a local ham that needs some assistance and
have found some strange things, some, but not likely all. The amp seems to
have been, how do we say it, worked on. Everything seems to be ok except
on 160 meters. Original tubes in the amp were soft, so I put in a known set
that were good, and that didn't change things in terms of the problem on
160.
Here is the test setup. Using a dummy load with 1:1 SWR. Power supply
is fine. No parasitics observed. Driving with a TR-7 (tests at 50 and 100
watts). SWR to the input of the amp is less than 1.2:1 so the input coil
is reasonably well adjusted. Power out is only 500-600 watts DC on a
calibrated wattmeter. Other bands, like 80 and 40, produce closer to 900
watts DC output. Typically the power goes down as you go higher in
frequency, which happens here on 80-15 meters, but 160 is way down.
Has anybody experienced anything like this with their L7? Inquiring
minds want to know.
73,
Evan, K9SQG
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