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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 |
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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 |
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Re: Plate blocking caps YC156
开云体育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:
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.? |
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Re: Dielectric grease for roller inductors ?
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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 ?
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Re: Dielectric grease for roller inductors ?
Clint, VE3CMQ
开云体育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 ? 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 ? |
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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 |
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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?? |
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Re: Plate blocking caps YC156
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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
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Re: Plate blocking caps YC156
开云体育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 ? From:
[email protected] [mailto:[email protected]] On Behalf Of Jim VE7RF ? Those style? caps? are? way? too? big in
diam,? like? 4-5" !? ? They? end? up?
adding too? much? stray? C.? ?Been? there,?
done? that.? |
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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? ?? |
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Re: Plate blocking caps YC156
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The 57/857 are toy sizes, the 859's are for the big
boys
?
Carl
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Re: Plate blocking caps YC156
开云体育I would prefer a single capacitor any time. ? 73 Peter ?
? From:
[email protected] [mailto:[email protected]] On Behalf Of Jim VE7RF ? HEC? (high energy? corp) has? detailed?
current? vs? freq? info). |
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Re: Plate blocking caps YC156
开云体育I used this trick on my two x 3-1000z amplifier. I cut and wound a flat coil and placed it as you suggested. Higher frequencies gained a ton of power. Before my C1 cap was always min. C On 12/25/2019 7:48 AM, Jim VE7RF wrote:
HEC? (high energy? corp) has? detailed? current? vs? freq? info). -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |
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Re: Plate blocking caps YC156
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 |
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Re: Plate blocking caps YC156
开云体育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 On 22/12/2019 6:12 pm,
tardivat@... wrote:
Anyone suggest a plate blocking cap brand? |
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Plate blocking caps YC156
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 |
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Re: 3CX3000F7 10-80m
A? 50 ohm? glitch? resistor...and a fast,? correctly? sized / rated HV? fuse? will? save? just? about? any fault.?
Note the? part? about correctly? sized? HV? fuse.? 1A? for? a 8877,? not? 3A. For? 3CX-3000A7? and? bigger? tubes, 50? ohms? is as low as? you? want for? the? glitch? resistor.? HV fuse? 1st.? Glitch resistor on? outboard side? of? fuse.? 50? ohm? glitch R......? ?LIMITS? fault? current? to a safe? value. ? HV fuse INTERRUPTS? ?fault? current.....? and? typ? <2msecs.? ? Don't? do? silly? stuff,? like a 10-15 ohm? glitch R...and? NO? ?HV? fuse......? you? will? do? severe? damage. Jim? ?VE7RF |
