I've got wood!
On 30/12/2019 12:46 am, Peter Voelpel
wrote:
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Rohde & Schwarz
uses no other type of
capacitor then mica for their atus.
On the photo you see
a 200pf mica by Jahre
in their 20KW tuner.
?
73
Peter
?
?
?
The?
problem?
with? broadcast? ?mica's (or? any? mica)?
is? they? won't handle? ?any current? on? higher?
freqs.? But? they are? NPO.? ?Drake used switchable
mica's? in their? MN-2000? ant? tuner (along?
with? 2 x air? variables).? ?Drake? used? 7
(SEVEN)? ?mica's? in? parallel....just? for 10m?
band.....just to handle 1200w? pep into? some? swr.? ?
Drake? used? a single? 700 pf? (NPO) mica? to?
pad? the 1600? pf? load? cap on? 80m band....? on
their L4B? 80-10? amp.?
Those CDE and? similar? mica? caps? are? typ
rated? at? ?1? mhz? for? max current.? >
6? mhz, they? have? fallen? off really? fast.?
>20? mhz,? they? are? down? to? nothing.?
Mica's? work? superb? on? low? bands (<6
mhz)....? and ceramic? caps work? superb? >2-3
mhz.?
For? a plate? block? cap, ceramic? is? used,?
since? we? require? a cap(s) that? will? handle
loads? of? current on? 21-29.7? mhz. (+6M).? ? On
lower? bands,? plate? block? cap? current?
drops? way? off.....non? issue.
HEC? is? still made? in PA...amish? country.??
Download? the? main? catalog for? CERAMIC?
??
Draloric is? still? made in? germany.?
Centralab? was? bought? out? by? ITT-Jennings.?
Centralab? (ITT-Jennings)? ? 857 /? 859? is?
the? same? as a HEC? ?HT-57? /? HT-59?
Everything? else? is? a chinese copy.? ?Also?
factor? in? the? heat? from? the? anode?
will? travel? down? the strap..to? one? side?
of? plate block? caps.?
Jim? ?VE7RF
