>Thanks for this info!
/\ Ur welcome, Bob.
>Knowing testing a vac relay is not trivial I simply
>shorted the contacts to ensure it was not the problem. :-)
>
/\ When a vacuum relay has gas, a current path exists to chassis-gnd -
even though the contacts are shorted externally.
later
>
>-----Original Message-----
>From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
>Behalf Of 2
>Sent: Sunday, June 03, 2001 9:37 AM
>To: nospam4me@juno.com; AMPS
>Subject: Re: [AMPS] more alpha info from Bob...
>
>
>
>>
>>Bob reports back in with many thanks and the
>>following.
>>-
>>[snip]
>>-
>>: Skipp,
>>: Here is a summary to date on my Alpha 77 (PA-77)
>>: Symptom: Very low power out on all bands (maybe
>>: 200w or so) Plenty of grid current. Plate current can
>>: be driven to 800+ ma and exhibits a very shallow
>>: dip at resonance. Resonance occurs nearly exactly
>>: where predicted by the manual into a 50-ohm load.
>>-
>>: Troubleshooting efforts:
>>-
>>: Note: Power being monitored by both external Bird
>>:and the internal meter (Bird was checked with another
>>: rig to ensure proper operation). The two agree.
>>-
>>: 1. Output vac relay checked both with meter and by
>>: shorting contacts.
>>... -
>/\ A good vacuum relay Must have a good vacuum. Vacuum relays can not
>be checked without using a high-potential tester to measure the
>HV-conductance of the vacuum across open contacts. Another essential
>test is contact resistance. To measure the resistance of contacts, put
>1.00A through the contacts and measure the V-drop across the contacts
>with a DMM. For example, a Jennings RJ1A vacuum relay should have no
>more than 10mV across closed contacts with 1A flowing. (10-milliohms).
>And, with 3500VDC applied to open contacts, there should be under 1uA
>leakage.
>- Vacuum capacitors also need to be checked with a high-potential
>tester. ("high-pot")
>
>cheers, Bob and Skipp.
>
>
>- R. L. Measures, 805.386.3734, www.vcnet.com/measures.
>end
>
>
>--
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>
>
- R. L. Measures, 805.386.3734, www.vcnet.com/measures.
end
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