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Re: Plate blocking caps YC156
Hi Jim
I will order some HT57's from RFparts. I wont take a gamble with the Chinese copies since they similar in price. I? order 5. I cant find any other caps with RF current ratings for the higher frequencies. RF parts only has rf current data for the HEC caps. Murata and Toshiba dont make RF ceramic capacitors anymore.? Thompson used to make some good capacitors but they? have stopped as well.? So this just leave the HEC, Dralorics(China) and the Chinese manufacturers. I suppose the?? ultimate option would be a fixed vacuum capacitor. I like HEC's because they will make a compact assembly. |
Re: Plate blocking caps YC156
What superb engineering by the RF? Gods R&S. Just look at that? excellent bandswitch and finger stock contacts. Their older test equipment aslo? has such displays of excellence in engineering. I can only imagine what their amplifiers look like inside. I wonder if Rohde&S made a autotine HF amplifer like the Collinas HF8022? I have seen? Marconi copy of the HF8022. The only difference was the cabinet color.
Henry |
Re: Dielectric grease for roller inductors ?
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OEP still makes variable caps and all the TX
variety use that grease/goo/goop
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Re: Dielectric grease for roller inductors ?
Oren Elliott? no? longer makes? rollers...? just? ?air? variables +? verniers.??
I'm? gonna? buy? some...'conducto? lube' .? ? 75%? pure? silver...and 25%? castor oil.? ?Made for? sliding? contacts. I? use? High? tech? 3M? air? filters? ?on? the? air? intake? to? both? hb amps.? ?Sealed on? top? side...except for? exhaust.? ? Zero? dust.? ? My? ?4 x gold? contacts? ?pinch? and slide on? the? sides of the? 3/8" silver? plated? ribbon.? ?It? needs? lube.? Center? bar? is 1"? square,? silver plated? ?square tubing,? ?with more? sliding contacts (8) on? all? 4? x sides.? ?And? still? more? sliding contacts (4)? ?at? each? end? of? the? sq tubing..where? they? brazed? on silver? plated? discs.? Jim? VE7RF |
Re: Plate blocking caps YC156
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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
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Carl ----- 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.
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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@...>: I've been using a Palstar AT1500CV roller inductor antenna tuner to tune my |
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 ?
Cliff Fox (KU4GW)
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 ? |
Re: Plate blocking caps YC156
¿ªÔÆÌåÓýWeight of that tuner is 900kg! ?
? 73 Peter ? From:
[email protected] [mailto:[email protected]] On Behalf Of Alek Petkovic ? I've got wood! On 30/12/2019 12:46 am, Peter Voelpel wrote:
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Re: Plate blocking caps YC156
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Re: Plate blocking caps YC156
¿ªÔÆÌåÓýRohde & 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 ? ? From:
[email protected] [mailto:[email protected]] On Behalf Of Jim VE7RF ? 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.? ? |
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
¿ªÔÆÌåÓýHow 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.? |
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
¿ªÔÆÌåÓýI 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 ? |
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 |