Re: Plate blocking caps YC156
Well, 4 HT-57's will be OK for a 8877 running hard. I use 6 for a 3CX1000A7 on 2M at 1500W. No drift
Carl
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----- Original Message ----- From: tardivat@... To: [email protected]Sent: Sunday, December 29, 2019 12:31 AM Subject: Re: [ham-amplifiers] Plate blocking caps YC156 Thanks for all the suggestions. The HT57's look like the easiest capacitors to get. Are HT57's now being made in China by HyEnergy? I see a lot of what looks like clone HT57's for sale on that Auction site. The last thing I want is a crap capacitor failing because I was too cheap to buy the real thing. Peter have you tried those Chinese Capacitors. I know that Draloric capacitors are now manufactured in China and that looks like a Draloric capacitor? I have couple of monster CDM Type 293 1200pf 15kv 15 Amps broadcast micas. Rated at 1mhz. I dont know what the current handling is at 30mhz? These are monsters 3.5 inc by 2.5 inches. Alek, I looked at the web page and found a couple that might be suitable. The K15U-1 15kV 470pF 40kVAR capacitors. They just look bulk and messy to strap them together. 4 x HT57S's strapped together would make a compact assembly as Jim has suggested. Thanks for all the tips Jim. Anyway thanks for the suggestions Henry
|
Re: Dielectric grease for roller inductors ?
I'm guilty too.... tune my roller inductor with 10 watts or so RF.
Never "fine tune" with QRO... just null with the capacitors. The noise bridge would be a much better solution.
Don W4DNR
Quoting "Cliff Fox (KU4GW)" <cliffku4gw@...>:
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I've been using a Palstar AT1500CV roller inductor antenna tuner to tune my
260 feet 450 ohm ladder line fed doublet antenna with since 2002 and
Palstar makes no recommendations at all in the user manual about using any
type of dieletric grease or any type of lubricant on the roller inductor.
It does tell how to clean it. I clean it every 3 or 4 months when I blow
the dust out of my Ameritron AL-80B amplifier. I use those little alcohol
pads like I use for my diabetes tests and insulin injections to clean it
with. They do say to make sure to not leave any fluid or anything on the
inside of the turns on the inductor so I just wipe the outside of the turns
and the small brass wheel that runs on the inductor turns until I get a
clean pad. Usually there's a little bit of black dirt on them when I clean
it. WA4GEG, Byron Campbell, who specializes in repair of Yaesu FT-1000MP
line of transceivers recommends not using a roller inductor tuner at all
because he says not getting a good connection can damage the T/R relay
which is what was wrong with my Mark-V. He recommends using a noise bridge
instead. I've been using my MFJ-259B antenna analyzer hooked up to a
MFJ-1700B coax switch box that accepts up to 6 transmitters and 6 antennas
as if it's a transmitter itself and then tuning the Palstar tuner settings
for the match and it works great! Once I get a match I always write the
settings down in a little book I made of 3" x 5" index cards stapled
together on one side. When I return to that same frequency again I can
usually tune up with those settings and get a match in under 5 seconds!
Happy New Years and very 73!
Cliff, KU4GW
On Sat, Dec 28, 2019 at 1:35 PM Jim VE7RF <jim.thom@...> wrote:
I have a RI-40 ribbon style (3/8" x .082") roller coil....with no
lube on it. Can I use permatex dielectric grease on it ?
My RI-50 roller coil came with what appears to be green coloured
grease on it.
Both rollers have the ribbon pinched with a pair of gold plated
contacts, 2 per side. Coil is fixed. Contacts spiral around the
inside.
SSON no longer sells either version. I bought the RI-50 new,
years ago. The RI-40 was obtained used.
Jim VE7RF
|
Re: Plate blocking caps YC156
Hi, All-
I have followed this discussion on plate blocking caps with great interest.
Just wondering if anyone in the group might have a copy of old Sprague
literature that might have the specs on some caps I have here-
p/n 399A259. They are marked "2500MMFD- 5KVAC". I've been told
they can handle around 30KVDC. I did check them quickly with my
hipot tester and they were fine at the max on that instrument, around
14KV. Mine seem to be surplus/seconds, possibly used. Big 1/4-20
male and female studs on them. Around 2in tall and over 2in dia.
Encapsulated in epoxy, it looks like. Some measured a bit low on
capacitance, as low as about 1800pF on a couple. The caps are not
marked as to capacitance tolerance. All were low, no big deal to me.
Best pair were around 2200pF on my AADE cap meter. Usage here
would be strictly HF, mostly the low bands. 10 meters is pretty
useless right now.
These are a real hoss of a capacitor, looks like, but I'd be interested
in knowing how they were spec'ed as to RF current vs. frequency.
Likely to find their way into some amplifiers running 4 to 6KV anode
voltage. I'm really not contemplating running multiples of these-
I think a single cap would suffice for anything I'm planning on doing
with them. Some might be fairly high plate impedance, running
higher supply voltages with relatively lower anode currents. Pi-L
output networks. Date codes on these caps are typically "63nn"
1960's manufacture.
All specs/comments/advice welcome- thanks, guys!
73, David K3KY
|
Re: Dielectric grease for roller inductors ?
I've been using a Palstar AT1500CV roller inductor antenna tuner to tune my 260 feet 450 ohm ladder line fed doublet antenna with since 2002 and Palstar makes no recommendations at all in the user manual about using any type of dieletric grease or any type of lubricant on the roller inductor. It does tell how to clean it. I clean it every 3 or 4 months when I blow the dust out of my Ameritron AL-80B amplifier. I use those little alcohol pads like I use for my diabetes tests and insulin injections to clean it with. They do say to make sure to not leave any fluid or anything on the inside of the turns on the inductor so I just wipe the outside of the turns and the small brass wheel that runs on the inductor turns until I get a clean pad. Usually there's a little bit of black dirt on them when I clean it. WA4GEG, Byron Campbell, who specializes in repair of Yaesu FT-1000MP line of transceivers recommends not using a roller inductor tuner at all because he says not getting a good connection can damage the T/R relay which is what was wrong with my Mark-V. He recommends using a noise bridge instead. I've been using my MFJ-259B antenna analyzer hooked up to a MFJ-1700B coax switch box that accepts up to 6 transmitters and 6 antennas as if it's a transmitter itself and then tuning the Palstar tuner settings for the match and it works great! Once I get a match I always write the settings down in a little book I made of 3" x 5" index cards stapled together on one side. When I return to that same frequency again I can usually tune up with those settings and get a match in under 5 seconds!?
Happy New Years and very 73!?? Cliff, KU4GW
On Sat, Dec 28, 2019 at 1:35 PM Jim VE7RF < jim.thom@...> wrote: I? have a RI-40 ribbon? style (3/8"? x .082")? roller? coil....with? no? lube on? it.? ? Can? I? use? permatex? dielectric? grease? on? it ?
My? RI-50 roller? coil? came? with? what? appears to be? green? coloured? ?grease on? it.?
Both? rollers? have the? ribbon? pinched? with a pair of? gold? plated? contacts,? 2? per? side.? ?Coil? is? fixed.? ?Contacts? spiral? around? the inside.
SSON? no? longer? sells? either? version.? ?I? bought the? RI-50? new,? years? ago.? The? RI-40 was obtained? used.? ? ?
Jim? VE7RF
|
Re: Plate blocking caps YC156
Weight of that tuner is 900kg!
?
?
73
Peter
?
?
I've got
wood!
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On 30/12/2019 12:46 am, Peter Voelpel wrote:
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
|
Re: Plate blocking caps YC156
I've got wood!
On 30/12/2019 12:46 am, Peter Voelpel
wrote:
toggle quoted message
Show quoted text
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
|
Re: Dielectric grease for roller inductors ?
I seem to recall that the Harris "RF Grease" for roller inductors was just Molybedenum Disulphide which is also conductive.
Besides moly greases have other attractive properties that is well suited to greasing applications
Henry
|
Re: Plate blocking caps YC156
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
|
Re: Plate blocking caps YC156
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
|
Re: Plate blocking caps YC156
Thanks for all the suggestions.
The HT57's look like the easiest capacitors to get.
Are HT57's now being made in China by HyEnergy? I see a lot of what looks like clone? HT57's for sale on that Auction site.
The last thing I want is a crap capacitor failing because I was? too cheap to buy the real thing.
Peter have you tried those Chinese? Capacitors. I know that Draloric capacitors are now manufactured in China and that looks like a Draloric capacitor?
I have couple of monster CDM Type 293?? 1200pf? 15kv 15 Amps broadcast micas. Rated at 1mhz. I dont know what the current handling is at 30mhz? These are monsters? 3.5 inc by 2.5 inches.
Alek,? I looked at the web page and found a couple that might be suitable. The K15U-1 15kV 470pF 40kVAR capacitors.? They just look bulk and messy to strap them together.
4 x HT57S's strapped together would make a compact assembly as Jim has suggested. Thanks for all the tips Jim.
Anyway thanks for the suggestions
Henry
|
Re: Plate blocking caps YC156
How about a CM88 CDE?? The one I have in my hand now is literally
bigger than my door knob to the room.? 10KV, 30A @ 1 Mhz.? :)
73/jeff/ac0c
alpha-charlie-zero-charlie
On 12/28/19 10:31 AM, Jim VE7RF wrote:
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Show quoted text
Nope,? you? got it? ass backwards.? Measure? the plate? block?
cap? current if u don't? believe me.? W8JI, W8ZR, and John? Lyles?
also? concur.?
At? 29? mhz,? the anode? to? chassis? capacitance? becomes? most?
of the resonant? tank? capacitance.? ?How? do u? ?think? the main?
tank? coil? gets? connected? to the tube? C.....? via? the? plate?
block? cap of? course.
If the plate? block? cap is? installed at the 50? ohm? end? of
the? PI /? PI-L? network,? then? u? end? up? B+? on? both? the?
tune +? load? caps, tank? coil(s),? bandswitch,? roller? coil?
(if? used).? It? would? work, but? u just? added a ton? of? stress
to? all? those? aforementioned? tank components.?
Those? 4-5" (100-120mm)? diam? 'puck'? style? caps? won't? handle
142A? like? 4 x? 250? pf? HT-59's? will.? ? Even? the?
?140-150-200-205-250 mm? 'puck'? style? caps? won't work.? ?Trying
to parallel 'puck'? style?caps? is an? exercise? in? futility.? 2
x 200mm? pucks eats? up? ?8" x 16.5" !?
As? Carl? noted,? the? Centralab? 859? /? HEC? HT-59? is only?
2.25" diam? x 3" long.? ?I mounted? 4 x HT-59's? on a 3" x 3"? x
1/4"? thick? piece? of? copper..? (used on a single 3CX-20,000A7,
27 mhz amp).
4 x HT-59's? are? good? for 25 kv, 142A? CCS,? and? 200? KVA....?
and? 1000? pf? total? C.? ? Good? luck? trying? to? find a? puck
style cap that? remotely comes? close? to? those? specs... they?
don't? exist.?
The? 'kva'? rating is? typ a non? issue.? ?Knowing? the
capacitance? of? each? block? cap, the? XC? of? each? block? cap?
is? easily? calculated.? ?We already calculated? the? current
through? each? block? cap.
Current? x? XC? =? AC? Vdrop? across? each? cap...which? is? typ?
a?very low? value.? ?The? AC? V? drop? +? any? bias (B+)? can't?
exceed the block? cap's? stamped? V? rating.? ??
The? AC? current? through? the? block? cap....? x? the AC? Vdrop?
across? the? cap = va power.?
Using the? 2 x 3x15 tubes on? 27? mhz? for the? following?
example.?
250? pf? = 23.59? ohms.?
100.93 A? /? 4? =? 25.23A? PER? each? of? the? 250? pf? caps ( 4 x
caps used? in parallel.)?
?23.59 ohms? ?x 25.23 A =? ?595 Vac? across? each? ?of? the? 4 x
caps.?
595 vac? x 25.23 A? = 15,012? VA? ?( 15 kva)? Per? cap.
Each? cap? rated? for 50? kva...so? within? spec.?
On low? bands,? like? 160 ,? ?XC? per? cap is a lot? higher, but
cap? current? is? very? low....so? it's? still a non? issue? as?
far? as KVA? ratings.?
Download? the? HEC catalog.? ?It? depicts kva/current / voltage vs
freq? in? graph? form? ?I? will? post? the? HEC Catalog on? this
site since,? since I? have it already? in PDF? form.? ??
Jim? VE7RF??
?
|
Re: Dielectric grease for roller inductors ?
?
Call Oren Elliott and ask what they use. They proviided me a blob in a pill
bottle decades ago but forget the name.
Also Palstar.
I
wouldnt use anything but what the pros use.
Carl
?
?
?
----- Original Message -----
Sent: Saturday, December 28, 2019 1:35
PM
Subject: [ham-amplifiers] Dielectric
grease for roller inductors ?
I? have a RI-40 ribbon? style (3/8"? x
.082")? roller? coil....with? no? lube on? it.?
? Can? I? use? permatex? dielectric?
grease? on? it ?
My? RI-50 roller? coil?
came? with? what? appears to be? green?
coloured? ?grease on? it.?
Both? rollers?
have the? ribbon? pinched? with a pair of? gold?
plated? contacts,? 2? per? side.? ?Coil?
is? fixed.? ?Contacts? spiral? around? the
inside.
SSON? no? longer? sells? either?
version.? ?I? bought the? RI-50? new,?
years? ago.? The? RI-40 was obtained? used.? ?
?
Jim? VE7RF
|
Re: Dielectric grease for roller inductors ?
I use lubriplate lithium grease on most of my shafts.? Someone recommended it to me years ago.? So far, nothing I have used it on has gummed up, and no electrical problems have presented themselves. ? Clint, VE3CMQ ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Jim VE7RF
Sent: December 28, 2019 12:35 PM
To: [email protected]
Subject: [ham-amplifiers] Dielectric grease for roller inductors ?? I? have a RI-40 ribbon? style (3/8"? x .082")? roller? coil....with? no? lube on? it.? ? Can? I? use? permatex? dielectric? grease? on? it ?
My? RI-50 roller? coil? came? with? what? appears to be? green? coloured? ?grease on? it.?
Both? rollers? have the? ribbon? pinched? with a pair of? gold? plated? contacts,? 2? per? side.? ?Coil? is? fixed.? ?Contacts? spiral? around? the inside.
SSON? no? longer? sells? either? version.? ?I? bought the? RI-50? new,? years? ago.? The? RI-40 was obtained? used.? ? ?
Jim? VE7RF
|
Dielectric grease for roller inductors ?
I? have a RI-40 ribbon? style (3/8"? x .082")? roller? coil....with? no? lube on? it.? ? Can? I? use? permatex? dielectric? grease? on? it ?
My? RI-50 roller? coil? came? with? what? appears to be? green? coloured? ?grease on? it.?
Both? rollers? have the? ribbon? pinched? with a pair of? gold? plated? contacts,? 2? per? side.? ?Coil? is? fixed.? ?Contacts? spiral? around? the inside.
SSON? no? longer? sells? either? version.? ?I? bought the? RI-50? new,? years? ago.? The? RI-40 was obtained? used.? ? ?
Jim? VE7RF
|
Re: Plate blocking caps YC156
Nope,? you? got it? ass backwards.? Measure? the plate? block? cap? current if u don't? believe me.? W8JI, W8ZR, and John? Lyles? also? concur.?
At? 29? mhz,? the anode? to? chassis? capacitance? becomes? most? of the resonant? tank? capacitance.? ?How? do u? ?think? the main? tank? coil? gets? connected? to the tube? C.....? via? the? plate? block? cap of? course.
If the plate? block? cap is? installed at the 50? ohm? end? of the? PI /? PI-L? network,? then? u? end? up? B+? on? both? the? tune +? load? caps, tank? coil(s),? bandswitch,? roller? coil? (if? used).? It? would? work, but? u just? added a ton? of? stress to? all? those? aforementioned? tank components.?
Those? 4-5" (100-120mm)? diam? 'puck'? style? caps? won't? handle 142A? like? 4 x? 250? pf? HT-59's? will.? ? Even? the? ?140-150-200-205-250 mm? 'puck'? style? caps? won't work.? ?Trying to parallel 'puck'? style?caps? is an? exercise? in? futility.? 2 x 200mm? pucks eats? up? ?8" x 16.5" !?
As? Carl? noted,? the? Centralab? 859? /? HEC? HT-59? is only? 2.25" diam? x 3" long.? ?I mounted? 4 x HT-59's? on a 3" x 3"? x 1/4"? thick? piece? of? copper..? (used on a single 3CX-20,000A7, 27 mhz amp).
4 x HT-59's? are? good? for 25 kv, 142A? CCS,? and? 200? KVA....? and? 1000? pf? total? C.? ? Good? luck? trying? to? find a? puck style cap that? remotely comes? close? to? those? specs... they? don't? exist.?
The? 'kva'? rating is? typ a non? issue.? ?Knowing? the capacitance? of? each? block? cap, the? XC? of? each? block? cap? is? easily? calculated.? ?We already calculated? the? current through? each? block? cap.
Current? x? XC? =? AC? Vdrop? across? each? cap...which? is? typ? a?very low? value.? ?The? AC? V? drop? +? any? bias (B+)? can't? exceed the block? cap's? stamped? V? rating.? ??
The? AC? current? through? the? block? cap....? x? the AC? Vdrop? across? the? cap = va power.?
Using the? 2 x 3x15 tubes on? 27? mhz? for the? following? example.?
250? pf? = 23.59? ohms.?
100.93 A? /? 4? =? 25.23A? PER? each? of? the? 250? pf? caps ( 4 x caps used? in parallel.)?
?23.59 ohms? ?x 25.23 A =? ?595 Vac? across? each? ?of? the? 4 x caps.?
595 vac? x 25.23 A? = 15,012? VA? ?( 15 kva)? Per? cap.
Each? cap? rated? for 50? kva...so? within? spec.?
On low? bands,? like? 160 ,? ?XC? per? cap is a lot? higher, but cap? current? is? very? low....so? it's? still a non? issue? as? far? as KVA? ratings.?
Download? the? HEC catalog.? ?It? depicts kva/current / voltage vs freq? in? graph? form? ?I? will? post? the? HEC Catalog on? this site since I? have it already? in PDF? form.? ??
Jim? VE7RF??
|
Re: Plate blocking caps YC156
?
Not even close at?2.25" wide by 3"
tall..? Ive vever used them above?160 anyway and that was in?an
Omega match of a shunt fed?big 4 el 10/15/20 yagis top loaded
100'?tower in the mid 80's.?Resonant frequency was around 1500
kHz.?The RF HV was arcing a 7KV variable in a plywood box at only 1200W.
Moisture loaded air didnt help.
?
Modified another cheap hamfest variable for about
11 KV spacing for fine tuning and all was fine for a few years before moving
here.
?
Carl
?
----- Original Message -----
Sent: Friday, December 27, 2019 12:47
AM
Subject: Re: [ham-amplifiers] Plate
blocking caps YC156
Those style? caps? are? way? too? big
in diam,? like? 4-5" !? ? They? end? up?
adding too? much? stray? C.? ?Been? there,?
done? that.?
HT-57? in 200? pf is rated at?
?15A? CCS...and? 35KVA.? ? ?4 in?
parallel? make? for a compact? plate block? assy.?
?Good? for 60A? +? ?140 KVA..on? 10M?
band.??
To calculate? current through a plate?
block? cap? assy? is? as? follows.?
1)
calculate? XC? of? tube(s)? ?anode to? grid
C...? ( which? will? increase? with? tube?
in? socket...or? grid flange bolted? to? chassis.?
Caused? by? proximity of lower anode? fins? to?
chassis.)??
2)? calculate RF? RMS voltage at
anode.? ?( .6 X LOADED B+)
3)? ?RMS? voltage
/? Tube XC? ?=? ?RF? current through?
plate? block? cap assy.? ?
Example.?
?YC-156 on? 29? mhz.? ?52? pf? from?
anode? to? chassis.....? measured? with LCR
meter.?
1,000,000? /? (2 x pi x F x C
)?
=? 1,000,000? /? (6.28 x 29? x
52)
=? 105.6? ohms? ? of? XC? on?
?29? mhz.
Assume? ?a loaded? B+? of?
6? kv.?
RF? voltage is? ?.6? x 6000?
?=? ? 3600 vrms.
3600 / 105.6? ?=?
?34.1? Amps flowing through? plate? block? cap?
assy.....? on? 29? mhz.?
? Above?
is? the? worse? case...(6M? is? even?
worse).? ? ? Do? a similar? calc? for?
lower? bands.? ?On 14.5 mhz,? ?xc? is now
211? ohms.? Plate? block? cap? current? is?
down? to 17.05? amps. (8.5 amps? on? 40M....?
4.26? amps on 80M...... and 2.13 amps on? 160M.?
??
HT-59 in? a? 250pf version? is?
good? for 35A? +? 50? kva.? ?On buddy's? 2
x 3CX-15,000A7? amp? on? 27? mhz,? things?
go? crazy.? EACH? tube? is? 62 pf? from?
anode? to? chassis.?
XC? =? 47.56 ohms?
? ? Loaded? B+? is? 8 kv.? ?RF?
voltage = 8000? x? .6? = 4.8 kv
Current? through
plate? block? cap assy =? ?4800 / 47.56? = 100.93
Amps.?
4 x HT-59's in? 250 pf version? used.? (1000
pf? total).? ?Good? for?
140A?
Later....? Jim? VE7RF?
??
|
Re: Plate blocking caps YC156
Jim,
?
Why should the circulating RF current you
calculated, depending on Xc of the YC-156, flow through the plate blocking cap?
In the 29MHz case most anode capacity will
be within the tube and therefore only a small percentage of that RF current is
flowing through the blocking and tuning caps.
?
And imagine the plate blocking cap being
at the 50 ohm side of the pi coil which I frequently prefer...
?
Tell me why the size of 4-5¡°
diameter for a blocking capacitor matters when a pair of 3CX15000A7 is used?
You will need at least a 8-10¡° width
of copper sheet to mount 4x HT59 in a square on it.
?
73
Peter
?
?
Those style? caps? are? way? too? big in
diam,? like? 4-5" !? ? They? end? up?
adding too? much? stray? C.? ?Been? there,?
done? that.?
HT-57? in 200? pf is rated at? ?15A? CCS...and?
35KVA.? ? ?4 in? parallel? make? for a compact?
plate block? assy.? ?Good? for 60A? +? ?140
KVA..on? 10M? band.??
To calculate? current through a plate? block? cap?
assy? is? as? follows.?
1) calculate? XC? of? tube(s)? ?anode to? grid
C...? ( which? will? increase? with? tube?
in? socket...or? grid flange bolted? to? chassis.?
Caused? by? proximity of lower anode? fins? to?
chassis.)??
2)? calculate RF? RMS voltage at anode.? ?( .6 X LOADED B+)
3)? ?RMS? voltage /? Tube XC? ?=?
?RF? current through? plate? block? cap assy.?
?
Example.? ?YC-156 on? 29? mhz.? ?52?
pf? from? anode? to? chassis.....? measured? with
LCR meter.?
1,000,000? /? (2 x pi x F x C )?
=? 1,000,000? /? (6.28 x 29? x 52)
=? 105.6? ohms? ? of? XC? on? ?29?
mhz.
Assume? ?a loaded? B+? of? 6? kv.?
RF? voltage is? ?.6? x 6000? ?=? ? 3600
vrms.
3600 / 105.6? ?=? ?34.1? Amps flowing through?
plate? block? cap? assy.....? on? 29? mhz.?
? Above? is? the? worse? case...(6M? is?
even? worse).? ? ? Do? a similar? calc?
for? lower? bands.? ?On 14.5 mhz,? ?xc? is
now 211? ohms.? Plate? block? cap? current?
is? down? to 17.05? amps. (8.5 amps? on? 40M....?
4.26? amps on 80M...... and 2.13 amps on? 160M.? ??
HT-59 in? a? 250pf version? is? good? for 35A?
+? 50? kva.? ?On buddy's? 2 x 3CX-15,000A7?
amp? on? 27? mhz,? things? go? crazy.?
EACH? tube? is? 62 pf? from? anode? to?
chassis.?
XC? =? 47.56 ohms? ? ? Loaded? B+? is?
8 kv.? ?RF? voltage = 8000? x? .6? = 4.8 kv
Current? through plate? block? cap assy =? ?4800 /
47.56? = 100.93 Amps.?
4 x HT-59's in? 250 pf version? used.? (1000 pf?
total).? ?Good? for? 140A?
Later....? Jim? VE7RF?
??
|
Re: Plate blocking caps YC156
Those style? caps? are? way? too? big in diam,? like? 4-5" !? ? They? end? up? adding too? much? stray? C.? ?Been? there,? done? that.?
HT-57? in 200? pf is rated at? ?15A? CCS...and? 35KVA.? ? ?4 in? parallel? make? for a compact? plate block? assy.? ?Good? for 60A? +? ?140 KVA..on? 10M? band.??
To calculate? current through a plate? block? cap? assy? is? as? follows.?
1) calculate? XC? of? tube(s)? ?anode to? grid C...? ( which? will? increase? with? tube? in? socket...or? grid flange bolted? to? chassis.? Caused? by? proximity of lower anode? fins? to? chassis.)??
2)? calculate RF? RMS voltage at anode.? ?( .6 X LOADED B+)
3)? ?RMS? voltage /? Tube XC? ?=? ?RF? current through? plate? block? cap assy.? ?
Example.? ?YC-156 on? 29? mhz.? ?52? pf? from? anode? to? chassis.....? measured? with LCR meter.?
1,000,000? /? (2 x pi x F x C )?
=? 1,000,000? /? (6.28 x 29? x 52)
=? 105.6? ohms? ? of? XC? on? ?29? mhz.
Assume? ?a loaded? B+? of? 6? kv.?
RF? voltage is? ?.6? x 6000? ?=? ? 3600 vrms.
3600 / 105.6? ?=? ?34.1? Amps flowing through? plate? block? cap? assy.....? on? 29? mhz.?
? Above? is? the? worse? case...(6M? is? even? worse).? ? ? Do? a similar? calc? for? lower? bands.? ?On 14.5 mhz,? ?xc? is now 211? ohms.? Plate? block? cap? current? is? down? to 17.05? amps. (8.5 amps? on? 40M....? 4.26? amps on 80M...... and 2.13 amps on? 160M.? ??
HT-59 in? a? 250pf version? is? good? for 35A? +? 50? kva.? ?On buddy's? 2 x 3CX-15,000A7? amp? on? 27? mhz,? things? go? crazy.? EACH? tube? is? 62 pf? from? anode? to? chassis.?
XC? =? 47.56 ohms? ? ? Loaded? B+? is? 8 kv.? ?RF? voltage = 8000? x? .6? = 4.8 kv
Current? through plate? block? cap assy =? ?4800 / 47.56? = 100.93 Amps.?
4 x HT-59's in? 250 pf version? used.? (1000 pf? total).? ?Good? for? 140A?
Later....? Jim? VE7RF?
??
|
Re: Plate blocking caps YC156
?
The 57/857 are toy sizes, the 859's are for the big
boys
?
Carl
?
?
?
----- Original Message -----
Sent: Monday, December 23, 2019 3:02
AM
Subject: Re: [ham-amplifiers] Plate
blocking caps YC156
Email Dr Alex.
Log into his page at
He will look after you and get you the correct capacitor, at the most
reasonable price.
73, Alek. VK6APK
Anyone suggest a plate blocking cap brand?
The only
capacitors that i can? get RF current data on is the HT57's. I was
thinking of using a couple of? HT57 1000pf in parallel. Its really hard
getting getting RF current data. Anything without RF current data I pressume
is just ordinary? non RF rated capacitors. RFPARTS publishes very
little RF current data so you dont know what you buying. What are people
using on YC156 type amps for 160 through to 10. The Pancake Dralorics are
massive? and the current seems limited on the higher frequencies that
is for the big 6 or 8 inch pancake types.
Henry
|
Re: Plate blocking caps YC156
I would prefer a single capacitor any
time.
?
73
Peter
?
?
?
HEC? (high energy? corp) has? detailed?
current? vs? freq? info).
For? 10-10? YC-156? amps,? use? 4 x?
HT-57's.? ?200 pf? are? the? go? to?
standard.? ?The? 200? pf? HT-57? will?
easily? handle 15A? @ 32 mhz.?
800? pf? is? ample,? even? for? 160m.??
The? YC-156? ends? up? being? aprx? 52 pf?
from? anode? to? chassis,? once? bolted? to?
chassis.? ?The? tube? provides most? of the?
tune? C...with the? tune? cap? being? a small
adjustable? padder? in? parallel.? Problem? is, the
plate? block? cap? is between? the? anode and
the? tune? cap.? Since? the? tube? C has?
most? of the? RF? current? flowing? through?
it...vs? the? tune? cap,? all? that anode to?
grid? Current? now? has? to? also? pass through
the? plate? block? cap? assy.? ?That's?
where? the plate block? caps? are? stressed...?
on? 10m ...and? upper? bands.?
Install a strap? coil? between? plate? block? cap
assy? and the tune cap..to? reduce? plate? load?
Z.? Then a PI? net? with a normal? loaded? Q can?
be? used.? You? can? see? that? effect? asap?
when? playing? with the? GM3SEK? PI spreadsheet.
I? posted a pix? of buddy's? 80-10? YC-156? amp?
under the? photo? page.? ?The? 160m?
monoband? YC-156? also? uses 4 x? HT-57's...also?
200? pf? each,? 800 pf? total.??
Jim? VE7RF
|
