What about the Millen HV connectors used in the DRAKE linears? de Han SM5KI
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>Från: "Tom Rauch" <w8ji@contesting.com>
>Till: amps@contesting.com, w.knol@niwa.cri.nz
>Ämne: Re: [AMPS] Surge voltage, HV connectors.
>Datum: tor 2 mar 2000 13.04
>
>
>> 1. The amp uses 2 x TB 2.5-300, which are rated at 2.5 kV.
>> The test bench version of the supply is a setup that uses microwave oven
>> transformers charging a capacitor bank. It surges to 2.8 kV (under bleeder
>> load only). Under 400 mA of load (the projected total plate current), the
>> HV drops to 2.1 kV. Can I expect problems with the 2.8 kV at the start of
>> a transmission or should I ignore the surge voltage?
>
>If you live a long distance from other people, and use small
>antennas, a supply that sags 25% won't make you unpopular.
>
>If you have a reasonable signal level, you will probably make others
>unhappy on occasion from the IMD distortion.
>
>Microwave oven transformers have horrible ESR, and make very
>poor linear amplifier power supplies.
>
>> 2. The HV supply will be an external, stand-alone unit. I am having
>> problems locating suitably rated HV connectors. The HV connector would
>> have to be a two pole type, making B- before making B+, and rated at >2.8
>> kVDC (to prevent the operator from being electrocuted)
>
>You might consider armored cable with a grounded metal shell,
>and using the second pin in the connectors as an interlock to
>prevent HV from being activated unless the HV lead is connected
>and the chassis are grounded together.
>
>BTW, and fault protection resistors belong in the HV positive lead
>down in the power supply, not up in the RF deck. That way if the
>HV lead faults against your pet cat who happens to chew on the
>HV lead, it won't blow his teeth out.
>
>> The ARRL handbook mentions Millen 37001 HV connectors. Are there any
>> places that sell these (or other suitable connectors) mail order in small
>> quantities? Are the Millens any good for what I want?
>
>The Millens, if they are the connector I am thinking of, are absolute
>junk. They break easy, they allow contact with HV lead, and they
>have a tendency to arc through. I've seen many of them mounted
>on plexiglas to prevent them from faulting to the chassis.
>
>> Ideally I would like an HV connector with a set of extra contacts for
>> carrying mains to the amplifier filament transformer as well.
>
>Never ever do that, unless you have a death wish for you or your
>family. Especially in NZ, where the power mains are not grounded.
>
>If you ever get a fault from the HV lead to the power line, and if the
>chassis is grounded, the power supply can elevate the power lines
>to whatever the HV is...or to the breakdown voltage of the poorest
>insulated earthing connection on the mains. That might be the
>neighbor next door, leaning on her blender while cleaning her
>kitchen sink.
>
>Use a decent separate interlocked HV connector, or make it
>difficult to disconnect it or difficult to forget to connect it when the
>supply is on.
>
>> considering an interlock cct preventing the HV supply from being turned on
>> unless the amplifier is hooked up. This would safeguard against a live
>> dangling HV connector. This requires a a pair of HV rated contacts and 5
>> extra contacts
>
>The HV chassis mount connector should be on the supply ONLY,
>not on the RF deck. Then the dangling lead has zero volts, even if
>the interlock system fails.
>
>I have a two inch diameter scar on my wrist from following Bill Orr's
>suggestions about power supplies, and using Millen connectors. I
>had a connector blow apart (or the wire did) and the wire flew about
>two feet or more and attached itself to my wrist.
>
>Opening a pair of 60 amp main breakers via your wrist and the HV
>supply is not fun.
>
>
>
>
>>
>> Any pointers to suitable connectors would be greatly appreciated.
>>
>> Wilbert, ZL2BSJ
>>
>>
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>>
>>
>
>
>73, Tom W8JI
>w8ji@contesting.com
>
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>
>
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