>
>Vic Rosenthal wrote:
>
>> I have been
>> successfully using an old Johnson 275-watt (AM) matchbox to feed a 40-m
>> dipole, ladder-line fed, on all bands at 800w CW for some time.
? I ran my E. F. Johnson 275w Matchbox at 1500w ssb pep with no sparks,
feeding a ladder-line/ dipole.. However, the Z matching range was so
limited that I sold the Matchbox.
>
>> I suspect that the KW version would be good for considerably more than 1500
watts PEP.
>
? I've heard of cases where it reportedly handled 3k pep-ssb, which is
semi close to a kW AM. .
>I forgot to add, for those who don't know, that the Matchboxes are
>link-coupled
>parallel-tuned, balanced circuits. The 4 to 1 balun in most modern tuners is
>very inefficient when the SWR on a balanced line gets above 3 to 1 or so.
>These
>tuners are really designed for coax or for balanced lines
? these tuners are typically T-networks, which are ideal for end-feeding
high-Z antennas such as the Hertz. A Matchbox won't.
- cheers, Vic.
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|