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CE20a power output?




 
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Author Topic: CE20a power output?  (Read 197 times)
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SA2CLC
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« on: May 25, 2023, 04:19:42 PM »

What kind of power out are you other 20A owners getting?

I'm getting around 12w into a dummy load on 80m, with power decreasing higher in frequency.
 
Curious to see if there's much room for improvement or not?
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WB6NVH
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« Reply #1 on: May 26, 2023, 04:07:43 AM »

What are you using for a VFO?  Power out is very dependent on the VFO excitation level and the band in use. Typical output on 80 would be about 14-16 Watts.
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Geoff Fors
Monterey, California
SA2CLC
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« Reply #2 on: May 26, 2023, 04:18:54 PM »

I'm currently using an HP8640 as vfo, while building an ESP32-si5351a dedicated vfo.
The 8640 appears to have enough drive, although I have not verified that there is at least 8v pk-pk on the grid of the mixer.
I say appears, because I can "peak" the transmitter output using the generator; if I increase the generator output above a certain level, the power out from the transmitter decreases.
The reason I'm looking for those last watts is because they are needed to drive the dual grid driven 813 linear. Right now it falls a bit short.

Checking output power using a crystal (only got a 40m) yields about the same power as with vfo, about 12w.

I did swap the cathode follower driver, a 12BH7, which increased the output power on 10m from 1.5w to almost 8w, which I'm quite pleased with, however,  no improvement on the lower bands.

A NOS (yeah right!) 6BA7 mixer off Epay gave less power than the one that was in the transmitter. (That tube tester build should have gotten priority over new projects!!).

I guess I should start measuring pin voltages before anything else. I did replace all capacitors, sans micas, but there are still possible drifted resistors in the mess.







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