On Sat, Feb 17, 2024 at 11:39 PM, Dave w6de wrote:
What are the issues with Ameritron Plate Chokes?
I have used an RF Parts look alike for several amplifier projects.
More chokes here
Unfortunately, RF-Parts now lists these parts as "No longer available for export."
When I worked for a US Defense Contractor, I found that Great Britain, Australia, and New Zealand were exempt from these restrictions.
It may be worth an inquiry to see if RF-Parts will recognize this.
Note: the RFC3 plate choke resonates at 10 MHz, and the Ameritron High Power Tube Amplifiers are not specified to run on the 10 MHz (30 Meters) band.
73,
Dave, w6de
##? 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)
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## 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 The small 0-4.4 uh roller coil ( 8 ga wire) was originally made by multronics.?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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## 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.?
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##? 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.?
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## 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.?
##? Depending on which of the 4 x? thickness'? used,? etc,? it can easily shift the 2 x series resonance freqs.? ?Get the gaps wrong, and they will shift again.? Slop too much/too little clear goop on the sides of the windings, and it shifts again.?
## 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.?
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## 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.?
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## 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.?
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## These days, I would check any plate choke on the vna, since they are so cheap (vna).?
