Evan -
Never had an L-7, so can't say definitively.
Have you measured the actual input power? The TR-7 output power falls
off on 160 because of the output filters, among other things. The
built-in wattmeter isn't the greatest either! I suspect the wattmeter
falls off on 160 as well, since the coupling unit efficiency is pretty low.
Same thing applied to the input circuit of the L-7. The input filter is
very low Q and lossy.
I don't remember, but was the power limit on 160 still 250W when the L-7
came out?
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
[email protected] 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
_______________________________________________
Drakelist mailing list
[email protected]
http://mailman.zerobeat.net/mailman/listinfo/drakelist
