Re: Stiff tuning capacitor
Well, I pulled out one of my blunt-needle syringes that I use for applying really small amounts of stuff, and hit both bearings of the air variable with a drop of Kroil, “The oil that creeps.” Love that stuff, but not cheap. Anyway, the cap is turning freely now. But I’m pretty sure this is a temporary fix. Time will tell. Prob need real lubricant in there.?
Richard
WB5NEN
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Re: Stiff tuning capacitor
Hi Don,
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That’s exactly what Lt.Cmdr (Ret.) MSRN Atilla the Hun
advises me from time-to-time.
?
Hal
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Re: High filament current on the 8877 amplifier tube
Hi Tim,
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What a great idea for proofing performance on 8877’s.
?
These things are carbonized in production with
burning acetylene gas. I’m sure there is a
controlled process combined with high vacuum
that sets the amount of carbon deposition, but what if
different amounts or densities of carbon settled in
the envelopes, making for a variance in filament
amperage?
?
Hal
W4HBM
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Re: Stiff tuning capacitor
3-in-One oil ... one drop.
W4DNR
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On 2023-10-12 7:42 am, Richard P via groups.io wrote:
Mine used to turn freely throughout its range, but now, it’s gotten kind of stuff. Annoying. Maybe a shot of penetrating oil on the “bearings,” or what??
Richard
WB5NEN
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Re: Stiff tuning capacitor
Be careful with WD40. It's flammable. I've had good luck with 0w-20 FULL SYNTHETIC engine oil. It also works well for clocks, guns, etc. Bob W4JFA?
On Thu, Oct 12, 2023, 10:44 AM HaL Mandel < hmandel@...> wrote:
Zoro.com sells tiny tubes of it….
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Re: High filament current on the 8877 amplifier tube
When I built my 8877 tube tester – I metered everything (four meters). It is amazing to see what happens with a cold 8877 and bringing up the filament voltage via a variac slowly to 5 VAC. A cold filament wants to draw lots of current. Bringing them up slowly is the key. That is why I have step starts on ?the filament voltage on my homebrew 8877 single band amps… ? So we (DL1QQ is helping) are testing the spare “fleet” of 8877s here (yearly event) at K3LR and so far twelve 8877 spares all draw 11 amps of filament current (after warm up). That is o Eimac spec. Four other 8877s draw 15 amps (HV has not been applied to these yet). I have 18 contest amplifiers here – they all use the 8877. So spares are very important. ? The 8877 tube HV tests vary from 300 mA to 410 mA at 2900 volts (also on a variac). The more current – the healthier (more output) the tube has. ? 73 Tim K3LR ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jim VE7RF
Sent: Thursday, October 12, 2023 10:27 AM
To: [email protected]
Subject: Re: [ham-amplifiers] High filament current on the 8877 amplifier tube ? I would also measure the C? between? anode to grid....and also grid to cathode, and also anode to cathode..... and also cathode to heater.? Still baffles me why a tube would draw 36% more current.? ? Then again, how many owners of 8877? amplifiers? measure fil current, probably none.? I? measure? fil current on all my hb triode amps, with directly heated cathodes....with a front panel, panel meter.? Just a 0-75 amp meter, with the mating 75:5 xfmr...that loops around one of the fil leads... on? my 3x3 amp.? The 3x6 amp gets a 0-100 amp meter, with the mating 100:5 xfmr.? ?'Step start' in both cases consist of bringing up the small variac real slowly till desired voltage is obtained...(on a separate fil V meter).??
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Re: Stiff tuning capacitor
Zoro.com sells tiny tubes of it….
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Re: High filament current on the 8877 amplifier tube
I would also measure the C? between? anode to grid....and also grid to cathode, and also anode to cathode..... and also cathode to heater.?
Still baffles me why a tube would draw 36% more current.? ? Then again, how many owners of 8877? amplifiers? measure fil current, probably none.?
I? measure? fil current on all my hb triode amps, with directly heated cathodes....with a front panel, panel meter.? Just a 0-75 amp meter, with the mating 75:5 xfmr...that loops around one of the fil leads... on? my 3x3 amp.?
The 3x6 amp gets a 0-100 amp meter, with the mating 100:5 xfmr.? ?'Step start' in both cases consist of bringing up the small variac real slowly till desired voltage is obtained...(on a separate fil V meter).??
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Re: Stiff tuning capacitor
Thank you. Yes, air variable. I do not have the moly di grease, but my neighbor has everything. I’ll check with him to see if I can get a dollop.?
R
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Re: Stiff tuning capacitor
Dear Richard,
?
Sorry to hear of your difficulty with
a stiff-turning capacitor.
?
I had not seen any prior posts from you
describing the component, so I’m not sure
of exactly how to proceed.
?
If you are talking about an air-variable
there are bearings on the front and rear plates
that need to be lubricated.
?
WD-40 will temporarily free it up, but the
best solution is to use a small amount of
molybdenum disulphide grease on a thin, thin
screwdriver, then to follow with a drop or two
of engine oil on the dabs of grease, then
follow up with moving the cap through all
its motion. The moly grease is conductive
plus it will work its way into the bearings.
?
You will see wipers on both ends that need a bit
of lube as well.
?
If you are talking about a vacuum cap, the actuator
screw can be removed and a bit of lube on the
threads and around the steel thrust washer will
work well.
?
Hal Mandel
W4HBM
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Mine used to turn freely throughout its range, but now, it’s gotten kind of stuff. Annoying. Maybe a shot of penetrating oil on the “bearings,” or what??
Richard
WB5NEN
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Re: High filament current on the 8877 amplifier tube
Hi Jim,
?
The 36 percent higher current is certainly a head-scratcher,
but there are tests for carbonized filament tubes. Some I know:
?
Filament resistance cold -vs- Filament resistance warm (Good DVM).
?
High Voltage HIPOT, various pins to various pins.
?
Emissions Test with a calibrated load and calibrated
Plate Current ~ Grid Current.
?
Stack all this up against a known good tube with the same
sort of testing. If results are whacky (As in “Tabaccy,) use
a third known good bottle.
?
Somehow, somewhere a performance statistic will result.
A known dud is a possibility, even.
?
Maybe the tube in question suffered a minor Funderberg
occurrence, like a fission reactor, it might have had a
small “excursion.” And now the Piper is calling. Looking
for that gold sputtering deposition on the filament strands,
perhaps.
?
Give her a whack straight down on a hard surface, once, and
see if the DC resistance changes ever so slightly.
?
Your view?....
?
Hal
W4HBM
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Re: High filament current on the 8877 amplifier tube
Hal, that does not explain why his tube is pulling 36% more current than normal.?
Dunno abt the 8877, but typ high mu, directly heated tubes have a cold resistance that's typ 1/10 of the hot resistance.
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I use an external 8x8x4 box for the step start on my drake amps, and step start the entire mess,? B+? and the fil.? (20 ohm resistor is manually shunted out after 2-3 secs).?
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On the bigger HB amps,? I use a sola constant V xfmr to supply the regulated? 240/120? to the small variac, that feeds the fil xfmr. On those amps, I just slowly bring up the fil V every time, to desired vac.?
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Re: High filament current on the 8877 amplifier tube
Dear Tim,
?
The 8877 tube benefits from having a filament voltage
Current-limiting scheme, such that the initial surge
Is limited. A ham operator, some years back, demonstrated
That a cold 8877 might well draw over 100 amperes for
One-half an a.c. cycle, and that could warp the filament
Structure.
?
The 8877 is a strong performer, but like any other
High-mu dilettantes need sheltering and mothering
To prevent catastrophes. Limiting the grid current
Is another category, but correct filament startup
And voltage regulation comes first. You only get
Five percent below and five percent above to play
With.
?
Hal Mandel
W4HBM
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High filament current on the 8877 amplifier tube
Most 8877 tubes that I test draw 11 amps of filament current at 5 volts. I have tested three recently that draw 15 amps of filament current. All of these tubes are used and have little “dings”. ? Is 15 amps an indication of a problem tube? Or should I apply HV to the plate and see what happens? ? 73 Tim K3LR
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> They are in their original foam filled boxes. Photos attached. Thanks & 73 – Mike ? I believe it is essential that you learn how to reduce your images before posting them. Online, your email has the astronomical size of 17.5 MB. Imagine the waste that such a publication will cause. ? As an example I am posting one of your images 5.86 times smaller. Do you see a big difference on your screen? 73 De la part de Mike Feher
贰苍惫辞测é?: jeudi 5 octobre 2023 01:59
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Re: 12 kw 160-12m amp for sale.
Wow. dOnT mISPell? w0rd here.?
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On 4 Oct 2023, at 8:30 pm, Mike Feher <n4fs@...> wrote:
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Whoops. I made the same mistake. I know what I meant, HI. 73 – Mike
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
?
?
Careful, Mike…..!!!!
?
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Of course you know that he meant 3CX1500A7. BTW, I have 3 NOS 3CXP1500A7 tubes for sale. 73 – Mike
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
?
?
3CX1511A7...?
No such tube...
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Re: 12 kw 160-12m amp for sale.
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On 4 Oct 2023, at 8:30 pm, Mike Feher <n4fs@...> wrote:
? Whoops. I made the same mistake. I know what I meant, HI. 73 – Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ? ? Careful, Mike…..!!!! ? ? Of course you know that he meant 3CX1500A7. BTW, I have 3 NOS 3CXP1500A7 tubes for sale. 73 – Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ? ? 3CX1511A7...?
No such tube...
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So, the tubes I have are actually 3CPX1500A7 tubes. These are the pulse rated 8877 tubes. I would like $1800 for all three. They are in their original foam filled boxes. Photos attached. Thanks & 73 – Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ?
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Re: 12 kw 160-12m amp for sale.
Oops, 3CX1500A7-8877.
I have two amps with this tube and a NOS spare-not for sale.? Alpha 9500 and a Henry 3002A.
?
73,
Dave, w6de
?
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From: [email protected] < [email protected]>
On Behalf Of Dave w6de via groups.io
Sent: 3 October, 2023 20:56
To: [email protected]
Subject: Re: [ham-amplifiers] 12 kw 160-12m amp for sale.
?
A bunch of DXers and Contesters I had work week regular lunch meet.? We had a saying: If your tube doesn’t have handles you aren’t squat. (Polite version.)
?
QRO comes in more than one form.? The most common are high horsepower cars. Another is powerful computers.
My current QRO is from a 3CX1511A7.
?
73,
Dave, w6de
?
These guys are a waist of time on the internet.? Where do they get the time and money to build this stuff.? When I see them discussing stuff that is not legal,? I just delete it.
?
?
?
?
You know, I figured I'd get something like this ( hits self in head ).? Sheesz
Andy? K9ATX
On 10/2/2023 11:19 AM, Joe WB9SBD wrote:
Something efficient and has very low losses.
Joe WB9SBD
On 10/2/2023 10:48 AM, DupyRail wrote:
Wondering what kind of antenna is used that will handle this much power?
A
On 10/2/2023 10:33 AM, Jim VE7RF wrote:
I designed this amp (back in 2007) for a buddy, who is now SK. Current owner is in MT. It uses a custom 253 lb Dahl plate xfmr and 24 x 3900uf lytics. Vac relays used for
the input + cut off bias. Paralleled Jennings RJ2B's used for the output. We tested the manually tuned, tuned input with a 800 watt CCS cxr for 10 mins, on each band. Input swr is dead flat across all bands. Triple wafer model 85 switch used for the 12 kw
PI net. Multronics MI-14 1/2" tubing coil used for 160-80-60-40-30m. HB 1/2 tubing coil used for 20-17-15-12m. This is a 9 band amp. 1000 pf @ 15 kv jennings tune cap. 3000 pf @ 5 kv jennings load cap. Bias is adjustable, on the fly with a 20 position rotary
switch. Dual line section bird, with 25 kw forward slug and 1 kw reverse slug. Pep board also installed. Kicks offline if reflected power too high. 10 kw out with 500w of drive. 12 kw with 600 watts of drive. 7-16 DIN output connector. I also have a spare,
nib blower, on my shelf. 253 lb dal xfmr has pri taps at 198-208-218 vac....and also 230-240-250 vac. Sec taps at 2300, 2900, 3900, 4600, 5000, 5400 vac. ( single phase 60 hz). 3 x 300 amp contactors used on the 240 vac input. One per each leg..and the 3rd
one used for the step start. Separate step start and variac used for the fil xfmr. There is only 5600 hrs on the hour meter. You need 200 amp service...and also a 100 amp breaker installed in the main 200 amp panel...and a min of 3 ga copper wire from main
panel to amp.
If interested, contact the seller below.
A SUPERBLY HAND BUILT 3CX-6000A7 HF AMPLIFIER IN A 6 FT RACK ON WHEELS. DESIGNED BY A PROFESSIONAL ENGINEER. PETER DAHL HV SUPPLY WITH TAPS DELIVERS UP TO 8000 VDC AT 3 AMPS.
ANY TRANSCEIVER WITH A 500 WATT INTERMEDIATE AMP CAN PRODUCE OVER 10KW OUTPUT. INPUT AND OUTPUT BAND SWITCHES WITH TUNED PI NETWORKS FOR ALL HAM BANDS 160-12 METERS AND TUNABLE TO OTHER HF FREQUENCIES 3.5-24 MHZ. HUGE ADJUSTABLE OUTPUT VACUUM CAPS AND VACUUM
RELAYS. ADJUSTABLE BIAS FOR BOTH LINEAR AND CLASS C. EXTENSIVE METERING, PROTECTION CIRCUITS AND FUSING THROUGHOUT. OVER $10,000 IN PARTS AT 2010 PRICES AND UNTOLD HOURS WERE SPENT BUILDING AND PERFECTING THIS INCREDIBLE MACHINE. WE CALL IT THE MONSTER AMP.
ASKING $10,000 OR BEST OFFER. WE HAVE DETAILED PHOTOS. ONSITE DEMONSTRATION OF THIS AMP’S OPERATION AND CAPABILITES IS AVAILABLE IN MONTANA. TOO HEAVY TO SHIP. SERIOUS BUYERS CALL 406-240-5428 OR 406-830-6360 FOR MORE INFORMATION. NOTE: OPERATION HIGHER THAN
1500 WATTS IN US HAM BANDS VIOLATES FCC RULES.
?
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"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
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Web page: ?
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Youtube Channel: ?
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"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
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Web page:?
?
Youtube Channel:?
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HaL Mandel
Bob
