[Amps] SB-220 low output on 10 was: SB-220 input problem

[Jim Hargrave]

When I was in the Air Force we had Collins KWM-2s. My personal equipment was a Collins KWM-1. It was recommended that we match these radios to amplifier with a 21 ft. coax. 

My rememberer has forgotten the explanation, but it seems effective with my Clipperton-L and homebrewed 2x4-400's amplifiers. Both are GG without input tuning.      

Jim – w5ifp-


>> -----Original Message-----
>> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of
>> N4ZR
>> Sent: Sunday, December 9, 2018 4:04 PM
>> To: Jim <jimw7ry at gmail.com>; amps at contesting.com
>> Subject: [Amps] SB-220 low output on 10 was: SB-220 input problem
>> 
>> I'll be ... I don't understand why, but putting 8-10 feet of RG-8X
>> between the K3 and the amp brought the input SWR down to
>> ~1.5:1.  I'd love to know how come.  Power output is still quite low
>> (~600W.)
>> 
>> Could be these 30-year-old 3-500Zs are finally wearing out.  Does
>> that normally show up on higher bands first?
>> 
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>> 
>> On 12/8/2018 11:46 PM, Jim wrote:
>> > A 6' cable between the amplifier and the radio is minimum length.
>> I
>> > use RG58 or RG8-X.
>> >
>> > Then see what the SWR is.
>> >
>> > Thanks
>> > 73
>> > Jim W7RY
>> >
>> > On 12/8/2018 7:14 AM, N4ZR wrote:
>> >> My SB-220 is showing a relatively high input SWR on 10M (about
>> 2.5:1)
>> >> - which I just discovered this weekend!
>> >>
>> >> Before I burrow into it, what's the most sensible approach?
>> Acquire
>> >> the capacitors for the input network and simply replace them
>> all?  Or
>> >> is there somewhere else I should be looking for my problem?
>> >>
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