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+--- Thread: ACOM1500 Plate Current ? (/thread-1352.html)
ACOM1500 Plate Current ? - VK4CCV - 04-11-2023
G'Day All,
What do you believe would be the expected Plate Current of an ACOM-1500 Amp??
I have one which all of a sudden the Power Out at the same low power In has increased (9W).
On 20m I have an output of around 350W with only 9W driving. This seems now to be across all bands.
I checked the Plate Current and I see around 450mA and 0-10mA Idle.
How is that sounding?
Pete
RE: ACOM1500 Plate Current ? - VK4ADC - 04-11-2023
Pete
Best be guided by the tube limits, https://www.g8wrb.co.uk/data/Eimac/4CX1000A.pdf, or the Acom 1500 documentation.
The 10mA plate idle current seems low if you are running in a linear mode, eg AB1, but is possibly correct for some other non-linear mode eg CW.
The RF drive should be reasonably consistent across all bands if the input circuitry to the tube is properly designed and tuned.
Whether the 9W of RF drive is consistent for that output power is the real question...
One Youtube video on the 1500 indicated about 13dB power gain on 7MHz so that means that it should provide about 180 watts (13dB above 9 watts) out. Getting approximately double that indicates a power gain more like 16dB and your front panel display gives you the real/actual gain value.....
Doug
RE: ACOM1500 Plate Current ? - VK4CCV - 04-11-2023
G'Day Doug,
Thank heaps for the Spec Sheet. Yea that has put my mind at ease.
At 7 Mhz @ 8W Drive, it was showing an output of 247W which is a 14.5 db Gain. That I am happy with. All within spec.
At 1,200W Plate Current is 750mA. Again this is within spec.
Thanks Doug for helping me out - huge relief !!
Pete. DU7/VK4CCV
RE: ACOM1500 Plate Current ? - VK4CCV - 14-12-2023
Some feedback regarding the issue.
As it turns out, it was a ceramic capacitor from the Screen Bias to Ground. It was leaking therefore loosing the voltage to Ground.
One 10n Ceramic later and it was all up and running again.
Pete