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Re: Ameritron Plate Chokes
What is W8JI's email address for ordering parts? Thanks. Jay, K2ZT? On Sun, Feb 18, 2024, 12:22 PM Jim VE7RF <jim.thom@...> wrote: On Sat, Feb 17, 2024 at 11:39 PM, Dave w6de wrote: |
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Re: Inductive EHT filtering
I notice in the circuit of the Henry 3K, 4K EHT supply there is a 10H choke, with a 0.2uF capacitor *in parallel*.
0.2uF // 10H makes a parallel resonant circuit at 120Hz, nice trick to up the impedance and improve ripple rejection. Can't model it in PSUD so I'm just trying LtSpice.... |
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Re: Inductive EHT filtering
On 2/19/2024 7:52 AM, Tim Fern wrote:
I will definitely insulate the choke frame from the chassis, I thinkI wonder if a VERY careful examination of both the choke and the chassis and choke mounting hardware, including at the mounting holes for screws, might find some sign of soot from such HV arcing?? The soot resulting from when my 2K4A HV transformer winding arced to its frame right outside the winding wasn't initially visible, until I happened to wipe my finger across that area and saw the soot on my finger. Finding such soot might help prove this theory of the choke arcing to the chassis. Also, I, too, was wondering what spark gap Jim uses across the choke? I'd think you'd want it as small as possible; i.e., 0.005" if possible, just wide enough that dust across the acorn nuts doesn't short out the gap. Finally... I'm wondering whether a high current MOV might perform the function of the spark gap, except more reliably?? After all, we use them on the filament pins, where they're taking the full current of a discharging HV capacitor through the tube. It seems to me that I've seen MOVs connected across chokes in the past. Steve, K0XP |
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PA tube testing, Interesting findings.
I recently acquired a few Alpha amplifiers that needed repair.? Along the way I decided to test all 10 tubes I had on hand.?
I put each 3cx400A7 in one at a time, let the filament run for a while to burn in. I Applied 1500 volts for 10 minutes or so.. then Keyed up While monitoring Grid and Plate current for 5 minutes. I noted idle current and then applied 15w RTTY drive on 20 meters and noted output power.? Out of the 10, Two where bad, one had open filament and the other a grid short.? The other eight where all good. Output power for those eight tubes: 175 w 175 w 175 w 150 w 140 w 120 W 100 w 75 w I let them run each tube keyed for 5 minutes or so and power was stable, and no tuning would produce more.? All tubes ended up at pretty much exactly the same tune and load. ONE of the new tubes made 50W but after a cycle of key OFF and Key ON power rose up. 75, then 100, then 120.? It ended up at 175 over about a 10 to 15 minute period.? Interesting to see it rise up like that.? Something was coming back to life. ALL other tubes made power instantly. What is interesting is that even the tubes that have lower output power and gain at 15w, make FULL power in the amplifier.? ?I can take the two weak tubes, 75 and 100, and put them in the amp and make 1500w out with a woodpecker.?? I can put the best three in the other map and make 1800w.? ?I can remove them and put the weakest three in the amp and make 1800w. Is there a better way to test power tubes?? Or do you really need to just test them to full output?? I had reservations about applying 2700 volts to them right away, that's why I used 1500v and low drive. Some of the tubes where new and marked 1980 so some run time is probably advisable at low voltage. I guess the drive and or added B plus is overcoming the loss of gain? C |
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Re: Inductive EHT filtering
Thanks Jim, loads of great info here, just what I needed. ? Your Dahl choke is a beast, wow, I thought mine was a monster, but life has taught me that somewhere, there will always be a man with a bigger one :-) ? It might use my choke on a big single-phase triode supply here. I like the sound of -129dB ripple filtering¡. One of the problems using *any* tube amp with FT8 is that your radio neighbours report the signal is wide¡.. because they see the 100Hz sidebands on their decode screens even when they¡¯re -40, -60 or -80dBc ¡.ask me how I know this :-( ? PSUD is new to me...what a great tool, I¡¯m playing around with it now. I can change the load R to simulate what happens with different plate currents as power is applied¡.. but were you able to simulate how the output voltage changes with sudden changes in load R? I can¡¯t see how to do it in PSUD? ? I will definitely insulate the choke frame from the chassis, I think your analysis of Henry Amp choke fails is spot-on. And I¡¯ll copy the Acorn-nuts spark-gap across the choke. What width gap did you choose? ? The DC resistance of my 10H choke is 28 ohms, I currently have a big 56 ohm glitch resistor, I might swap that for a similar 33 ohm one here, depending what C2 I end up with. I know how much energy the tube can take. ? The 0.85A CCS rating is a bit lower than I would like. I¡¯m wondering what would happen to it at 2A or 2.5A? Does it just risk over-heating? or might the core saturate too and stop it being an inductor? (Am pretty sure it¡¯s not a gapped ¡°swinging inductor¡±.) ? Best regards ? Tim |
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Re: 8410/9500 Wattmeter Failure
¿ªÔÆÌåÓýActually, I applied for membership to that group a few weeks ago,
but still haven't heard from a moderator either way. Have been
trying to read through the "back issues" of posts in the Archive,
but something seems to be resetting when I try to read messages
going forward in time, and instead the next message displayed is
the prior one. Probly my phat phingerzes hitting the wrong key?
8-) 73, Steve K0XP
On 2/18/2024 8:02 PM, Alan - W5ARM
wrote:
There is an Alpha group here on "Groups.io", rather specific to the 9500, but I've seen inquiries regarding other Alpha models. In addition, Glenn Pladsen (AE0Q) often posts replies to issues posted there, and sometimes will email you direct regarding things posted on the forum. --
See my QRZ.com page at |
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Re: Ameritron Plate Chokes
¿ªÔÆÌåÓýDr Alex is alive and well. I bought and paid for some doorknob capacitors just yesterday. I try not to shop anywhere else. 73, Alek VK6APK. On 19/02/2024 12:29 pm, Jim VE7RF
wrote:
On Sun, Feb 18, 2024 at 09:25 PM, Peter Voelpel wrote: |
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Re: Ameritron Plate Chokes
On Sun, Feb 18, 2024 at 09:25 PM, Peter Voelpel wrote:
I saw those 4 uh? roller coils. I didn't get an answer back from Dr? Alex as to? what ga wire was used, or condition of them.? I have never ordered anything from him...so have no clue what the shipping costs are to VE7.? ?At the time, the war had just started, and Dr Alex? had vanished, and had to temp relocate for his own safety.? He showed back up several months later.? They look like a viable option, albeit shaft diam is < 1/4" (6.35mm),? non issue, as an adaptor can easily be fabricated by drilling out a 3/16" coupler? to? (I think)? ?the Russian 5mm shaft.?
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Re: Inductive EHT filtering
I just did this recently.? I bought a used Dahl? choke (4H,? 3 amps CCS, and 15 kv rated). Weighs 127 lbs and uses the same hypersil core as the Dahl 10 kva plate xfmrs...which also weigh 127 lbs.? Bought it across town from a ham, who got it from the? old? satellite uplink station, just north of me The date code is 1991, and it's in pristine shape.? They had a total of 19 of em.? It's called a? C-L-C? filter setup.? ? Basically? ?you take a regular? 'high C' standard B+? power supply, and add a choke in series with the B+...followed by a cap. In software, that's called adding a 'LC' section.? ?Mine is setup for 60 hz single phase. Modelling it all in software 1st (Duncan's PSUD-2), which does NOT handle 3 phase supplies, ( but will handle 50/60/400 hz single phase)... there are some? serious concerns, and caveats.? (You would probably need Spice, or LT-Spice, to handle 3 phase). In software, it all goes to hell, and fast, IF the added cap after the choke ( let's call it? 'C2')? is not at least the same value as the main filter cap before the choke.? It should really be 50-100% bigger than the main? 'C1' filter cap.? If the C2 is smaller than the C1 cap, what happens is you get this severe? yo-yoing... down-up-down-up-down-up output voltage waveform, until it finally settles down after 200-600 msecs, depending on values.? For something like say FM broadcast, non issue.? For? CW, and esp SSB, it's a real mess.? ?The 1st cap? (C1 cap) still gets hammered with the high AC ripple current, same as before the LC section is added.? ?The 2nd cap has extremely little rms current flowing into it.? With any flashover, you still need a fast, HV fuse in series with the? final B+ output, followed by a HD glitch resistor.? ?( I had that before the LC section added).? ?I got the choke for minimal cost, and so it's just a good experiment I always wanted to try out.... more to verify the software than any practical use.? End result is, it's gross overkill for ripple reduction.? ?Mine has a 0db cut off of just 1.7 hz...and a 3 db cut off of only ( I think) 2.5 hz.? Ripple reduction at 120 hz (2F on? single phase) is -129 db.? ?My L4B with it's 25 uf filter cap (8 x 200uf caps in series) is only -30 db... and 2.9% ripple.... which is blatantly obvious on any RF monitor scope, drives me nuts.?? The added LC section gets better. The harmonics of 120 hz, (240-360-480 hz etc)? ?get killed at an even greater rate.? The added LC filter attenuates above it's cut off freq at a rate of? 12 db per octave.? ? I verified all this through measurements. The software is dead on.?? Ok, here's what you don't want to do,? and that's wire the choke in series with the B-.? ? Reason is, any V drop in the B- is just extra, yo-yoing extra, unwanted bias on the GG triode.? ?And that is in addition to the normal regulated bias on the tube.? The V drop across the choke is simply the current through the choke? x DC resistance of the choke.? ?My 4H choke is 9.56 ohms when cold, and 10 ohms when warm.? I tested it with my small lab supply, and stuffed 3 amps? CCS through it for hrs...doesn't even get warm, stays at ambient room temp.? It does heat up with 6 amps through it.... and right where the gapped cores are.? ( it also becomes the mother of all electromagnets).? Crank the current up..and u will reach a point of thermal runaway.? ?With normal 2.6 to 3.0 amps of plate current through the 10 ohm? choke, = 25-30 vdc V drop.? I tested a 2nd choke, a new? Hammond 1H choke, which is rated at 1000 ma CCS....and has a 5.75 ohm resistance.? ?I tested it with 800 ma though it, stone cold.? The Hammond is only rated for 1 kv ( 1.5 kv hi-pot test)..so it has to be installed in series with the? B+....AND well insulated from the chassis.? Treat it like a string of 450 vdc lytics. ? Same deal on the big, 127 lb dahl choke.? ?It's wired in series with the B+, but well insulated from the chassis.? I used 4 x of those red...? HV glastic insulators, that come with threaded? 3/8" inserts in each end.? Choke sits on top of a pair of upside down aluminum U channel's....which are in turn? insulated? ( via 4 x glastics) from the? 1.5" thick plywood? base installed at the bottom of the rack.? ?Insulated from chassis, the V stand off is a non issue.? ?You will still get the normal V drop across the choke, but at least it's not adding bias to the cathode.? On any single phase (60 hz) FWB / FWD? B+ supply,? the raw DC ( before any filter cap)? has? 67% ripple...and ripple freq is 120 hz ( 2F). IE: caps get charged up (or topped up as folks in the UK say) 100/120 times per second on single phase......and? 300/360 times per second on 3 phase.? ?That's the HUGE advantage of 3 phase power.? ? Before you try the choke, measure it's DC resistance 1st..then model it in software.? ?And make sure it's not a swinging choke.? See if you can measure the choke on an LCR meter.? (peter told me eons ago, that with typ 3 phase B+ supplies,? a small filter cap was used, followed by the series choke...and no C2 cap).? The ripple is then down to zip.? If it works in software, it will work? in? the real world.? ?If your DC resistance on that 10H choke is high, like (as I suspect) in the 40-60 ohm range, any normal V drop across it, will be in addition to the V drop across any glitch resistor.? ? With the typ series string of resistors used for the multiplier string for the B+? HV meter,? you can put the? DVM across the last resistor, or 2nd or 3rd to last resistor,? and measure the AC ripple component...with a full bore load applied.? For my setup, for safety purposes...and to protect the choke,? I installed a HB adjustable spark gap across the choke terminals. Made from solid brass? 1/4-20 hardware, mounted on a pair of 3/4" x 3/4" x 1/6" thick aluminum angles.? Angles are mounted directly to the threaded studs on the choke.? Solid brass acorn nuts used where the gap resides.? Acorn nuts are semi domed, and ideal for this application.? If they get trashed, they are easily replaced.? ?Acorn nuts face each other.? Solid brass lock nuts are used to lock the gap into place....done with feeler gauges, and also a hi pot tester.? I also installed a surplus SPST Kilovac ceramic vac relay across the choke terminals.? I can shunt out the choke at any time, for testing purposes.? Typ, with any B+ to grid arc, or say B+ to chassis arc, the 50 ohm glitch resistor will? LIMIT the fault current to just.... B+ / 50 ohms.? Meanwhile, the fast? HV fuse before the glitch resistor assy? will open off in < 1-2 msecs every time.? The C2 cap will discharge 1st...followed by the C1 main cap. When the C1 cap discharges, all that fault current flows through the choke... with a resulting MASSIVE V spike across the choke.? Chokes impede current ( both AC + DC) by dumping voltage.? I'm 95% convinced this is why chokes fail shorted to the frame in Henry radio amplifiers that use a resonant choke input.? You can also simulate the fault current in software...it's an eye opener.? This is a problem when chokes are wired in series with the B+.....and are not insulated from the chassis and / or no spark gap used.? ?The spark gap across the choke trick was used by Harris, and several others in the past.? ?I just re-invented the wheel.? On software, you can see the normal negative / positive swing on the choke with normal plate current drawn, either CCS cxr, or up / down like CW / SSB.? ?Typ it's not very much, < 100 vdc.? ? The spark gap across the choke is dirt cheap to implement.? ? Jim? ?VE7RF |
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Re: 8410/9500 Wattmeter Failure
There is an Alpha group here on "Groups.io", rather specific to the 9500, but I've seen inquiries regarding other Alpha models. In addition, Glenn Pladsen (AE0Q) often posts replies to issues posted there, and sometimes will email you direct regarding things posted on the forum.
The Alpha 9500 group is HERE: /g/Alpha9500 Good luck. -- 73, ~Alan
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Inductive EHT filtering
I've built many EHT supplies over decades but have always used capacitive only, ripple-filtering.
Sitting below my desk for many years, is an inductor rated 7,500V, 0.85A CCS, 10 Henries. It came from an industrial RF heater. I've never seen one used in an EHT ham amplifier supply...has anyone experience of this? 10H, even with just 1uF after it, has a -3dB frequency of 50Hz, so it would be pretty effective at 300Hz (3-phase, full-wave ripple). But how would the inductive ripple filter respond with an SSB load? What happens if the tube flashes over? Are some extra protections required? Thanks Tim |
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Re: Ameritron Plate Chokes
¿ªÔÆÌåÓýRFP will not sell 3-500Z tubes to overseas buyers but I bought 4
of them through their Ebay store, no problem. They will send them
anywhere in the world. Go figure. 73, Alek VK6APK On 19/02/2024 3:34 am, Dave w6de wrote:
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Re: Ameritron Plate Chokes
¿ªÔÆÌåÓýThere are? Russian 4?H roller inductors.. They are available at Dr. Alex, UR4LL: ?
? 73 Peter, DJ7WW ? ? From: [email protected] <[email protected]> On Behalf Of Jim VE7RF via groups.io ## merrit Arnold's wife and son now run RF parts.? One of the girls who works there tells me arnolds wife is a ...'real piece of work'.? ?I know other folks who wanted to buy 4x10 tubes..and that was another item they would not ship overseas.? Bonny has some bug up her rear end, about some items that should not be shipped outside of the usa...siting....'only should be sold in america'.? The small 0-4.4 uh roller coil ( 8 ga wire) was originally made by multronics.? ?Then Cardwell condenser co? bought out multronics...and the same roller coils in the RF parts site were indeed stamped...'Cardwell condenser Corp'.? ?Cardwell sold out to 'Viking'? ?( who owns the custom clothing line).? ?I just ordered 2 of the rollers? directly from Viking, no fuss, shipped fast.? ?
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Re: Ameritron Plate Chokes
¿ªÔÆÌåÓýThank you for this write up. ? 73, Dave, w6de ? From: [email protected]
<[email protected]> On Behalf Of Jim VE7RF via groups.io
Sent: 18 February, 2024 17:22 To: [email protected] Subject: Re: [ham-amplifiers] Ameritron Plate Chokes ? On Sat, Feb 17, 2024 at 11:39 PM, Dave w6de wrote:
##? No they don't.? I just recently bought 2 x of the ameritron chokes from? RF parts. ( 2-3 yrs ago).? ?ONLY on some selected items, ( and that choke is NOT one of em, as of 5 mins ago) will they refuse to ship outside the USA.? I had also ordered a pair of 0-4.4 uh roller coils. RF parts would not export em.? I couldn't even get em shipped to a friend in the usa.? ?The only work around was to have a friend in the usa pay for em, and have em shipped to his usa address..... then re-send em to my address via USPS. ..( that advice came from the girl in the office, not the owner, bonny) ? ## merrit Arnold's wife and son now run RF parts.? One of the girls who works there tells me arnolds wife is a ...'real piece of work'.? ?I know other folks who wanted to buy 4x10 tubes..and that was another item they would not ship overseas.? Bonny has some bug up her rear end, about some items that should not be shipped outside of the usa...siting....'only should be sold in america'.? The small 0-4.4 uh roller coil ( 8 ga wire) was originally made by multronics.? ?Then Cardwell condenser co? bought out multronics...and the same roller coils in the RF parts site were indeed stamped...'Cardwell condenser Corp'.? ?Cardwell sold out to 'Viking'? ?( who owns the custom clothing line).? ?I just ordered 2 of the rollers? directly from Viking, no fuss, shipped fast.? ? ## never had any issues, ordering anything from the usa, never.? ?And ZERO issues with customs...items sail right to my front door.? Only the 'select items'? on RF parts site.? ?IMO, just another goofball outfit that I can't throw money at.? ? ##? I just tested both ameritron chokes on my VNA last week.? ?They resonate at? ?12.332 mhz....and also? 16.247 mhz.? ?They will not blow up on any of the 9 x ham bands.? ?They won't blow up on 60m band, and also 11 m.?? They will blow up on those 2 x freqs I stated,? +/-? 750 khz.? ? ## However, I know of at least 12 of em now, that have blown up in the last few years..... typ on 17m.? ##? W8JI sez he used to hand wind em on his machine, in his own shop...for use in all the Ameritron amps.? ?They have to be carefully wound, and using the same magnet wire, and correct placement of gaps, correct turns count on all 3 x windings, and also
correct amount of? that clear...'goop'? they slop on the sides, to keep the winding intact.? Magnet wire comes in 4 x different thickness's of enamel / formvar / nyclad? etc...and for each gauge.? You can also buy magnet wire in 1/2 gauges.? You can also buy
magnet wire in several different temp ratings...and also several different V ratings.? ?Depending on type of insulation used, and thickness,? that alone will change the dielectric constant.? ## JI sez he left ameritron in 2019. ( KM1H said JI got fired, but u know carl). After JI left, ameritron started? winding their own chokes....and it's a disaster.? JI said he had a ham ship? him an ameritron amp in for repair, ( made after 2019)? and? immediately saw that the plate choke is a? screwed up dog's breakfast.? He said he has seen that several times now.? He also said the gap between bottom winding,...and the chassis is way too close? vs his original version.? ? ## watch out.? Alpha copied the ameritron choke, and make their own version, which looks identical.... and works.? ?RF parts used to sell the alpha version, then switched to only the ameritron version, which is still screwed up.? How the hell they got the? 16.247 mhz? up higher towards the 17m band is beyond me.? ? ## W8JI now refuses to work on ANY ameritron amp, tube or ss.? ?He does sell the original version of the plate choke, built and tested to correct specs.? ?He makes the chokes in his shop, same as before 2019.? ? ## These days, I would check any plate choke on the vna, since they are so cheap (vna).? |
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Re: Ameritron Plate Chokes
On Sat, Feb 17, 2024 at 11:39 PM, Dave w6de wrote:
What are the issues with Ameritron Plate Chokes? ##? No they don't.? I just recently bought 2 x of the ameritron chokes from? RF parts. ( 2-3 yrs ago).? ?ONLY on some selected items, ( and that choke is NOT one of em, as of 5 mins ago) will they refuse to ship outside the USA.? I had also ordered a pair of 0-4.4 uh roller coils. RF parts would not export em.? I couldn't even get em shipped to a friend in the usa.? ?The only work around was to have a friend in the usa pay for em, and have em shipped to his usa address..... then re-send em to my address via USPS. ..( that advice came from the girl in the office, not the owner, bonny) ? ## merrit Arnold's wife and son now run RF parts.? One of the girls who works there tells me arnolds wife is a ...'real piece of work'.? ?I know other folks who wanted to buy 4x10 tubes..and that was another item they would not ship overseas.? Bonny has some bug up her rear end, about some items that should not be shipped outside of the usa...siting....'only should be sold in america'.? The small 0-4.4 uh roller coil ( 8 ga wire) was originally made by multronics.? ?Then Cardwell condenser co? bought out multronics...and the same roller coils in the RF parts site were indeed stamped...'Cardwell condenser Corp'.? ?Cardwell sold out to 'Viking'? ?( who owns the custom clothing line).? ?I just ordered 2 of the rollers? directly from Viking, no fuss, shipped fast.? ? ## never had any issues, ordering anything from the usa, never.? ?And ZERO issues with customs...items sail right to my front door.? Only the 'select items'? on RF parts site.? ?IMO, just another goofball outfit that I can't throw money at.? ? ##? I just tested both ameritron chokes on my VNA last week.? ?They resonate at? ?12.332 mhz....and also? 16.247 mhz.? ?They will not blow up on any of the 9 x ham bands.? ?They won't blow up on 60m band, and also 11 m.?? They will blow up on those 2 x freqs I stated,? +/-? 750 khz.? ? ## However, I know of at least 12 of em now, that have blown up in the last few years..... typ on 17m.? ##? W8JI sez he used to hand wind em on his machine, in his own shop...for use in all the Ameritron amps.? ?They have to be carefully wound, and using the same magnet wire, and correct placement of gaps, correct turns count on all 3 x windings, and also correct amount of? that clear...'goop'? they slop on the sides, to keep the winding intact.? Magnet wire comes in 4 x different thickness's of enamel / formvar / nyclad? etc...and for each gauge.? You can also buy magnet wire in 1/2 gauges.? You can also buy magnet wire in several different temp ratings...and also several different V ratings.? ?Depending on type of insulation used, and thickness,? that alone will change the dielectric constant.? ## JI sez he left ameritron in 2019. ( KM1H said JI got fired, but u know carl). After JI left, ameritron started? winding their own chokes....and it's a disaster.? JI said he had a ham ship? him an ameritron amp in for repair, ( made after 2019)? and? immediately saw that the plate choke is a? screwed up dog's breakfast.? He said he has seen that several times now.? He also said the gap between bottom winding,...and the chassis is way too close? vs his original version.? ? ## watch out.? Alpha copied the ameritron choke, and make their own version, which looks identical.... and works.? ?RF parts used to sell the alpha version, then switched to only the ameritron version, which is still screwed up.? How the hell they got the? 16.247 mhz? up higher towards the 17m band is beyond me.? ? ## W8JI now refuses to work on ANY ameritron amp, tube or ss.? ?He does sell the original version of the plate choke, built and tested to correct specs.? ?He makes the chokes in his shop, same as before 2019.? ? ## These days, I would check any plate choke on the vna, since they are so cheap (vna).? |
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Re: Ameritron Plate Chokes
Almost every plate choke I see in an ameritron that comes in for repair is not wound properly. I always ask if they had used on 17 meters when I see a fried one , answer is always yes.
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I tell everyone to stay of 17 , some listen and some don¡¯t. Ones that don¡¯t listen say they don¡¯t see anything online about issues on 17 meters. The plate choke issue with 17 used to be posted in numerous places, but now seems to have vanished. On 2024-02-17 18:22, Alek Petkovic via groups.io wrote:
Thanks Robert. There are numerous reports that a batch of the chokes |
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Re: Ameritron Plate Chokes
¿ªÔÆÌåÓýDunno mate. we're pretty much accustomed to paying double for everything in this part of the world, so we don't worry too much about it. Guess I'll hear from Tom when he fronts for work this week. Cheers, Alek.
On 18/02/2024 1:11 pm, Bob wrote:
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Re: Ameritron Plate Chokes
Alek, How much will it be for them to be shipped to you? Bob W4JFA? On Sat, Feb 17, 2024, 8:22 PM Alek Petkovic via <vk6apk=[email protected]> wrote:
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Alan - W5ARM
Bob