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THE AM BULLETIN BOARD => Technical Forum => Topic started by: SA2CLC on May 25, 2023, 04:19:42 PM

Title: CE20a power output?
Post by: SA2CLC 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?

Title: Re: CE20a power output?
Post by: WB6NVH 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.

Title: Re: CE20a power output?
Post by: SA2CLC 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.

Title: Re: CE20a power output?
Post by: W2JBL on June 01, 2023, 12:12:44 AM
I have had a few CE 20A's over the years and that's about what you are going to get. 8 watts on 10 meters is a big deal and your are lucky to see that.. I drove mine with a CE 458 VFO and also crystals. All these boatanchors suffer reduced power out on the higher bands. Most rigs are good for full power out on 80/40/20 but above that efficiency falls off and power out drops. Even my Collins 32V2 does not do well on 10 meters compared to what it makes on 75. Look up Larry NE1S. He's on this site and is the CE20A Guru. 
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