One Tube 6L6 Transmitter experiments 6

Having completed my 6L6 project for the time being with no doubt in my mind that I can improve the design still further with improved understanding. I read the RSGB Handbook 5th edition section on Transmitters and in particular tube oscillators. Revealed the link between the output impedence and how it impacts the behaviour of the oscillator. It states that you need to increase the capacitive load in order to stabilize the Transmitter. This is because the TX is only in the positive feedback stable condition when the feedback from the load is slightly capacitive. I found just the opposite on my TX ie as I increased the capacitive load the oscillator became less stable. I think this is due to a slight mismatch to the antenna load, meaning that in fact the load was still slightly inductive. Note that I did not try this test using a dummy load but instead I used my attic dipole which is not a perfect resistive load. However more analysis is required before I can be sure.

I was able to make a number of very good QSOs with stations all over the US this wekend and I received reports ranging from 459 to 589. Examples of contacts being WB3T, WB2PPQ, WA$DAX, KF8R, K9LWA. I find that even running full power at 4.5 wats still yields a stable transmitt signal although it is important to monitor the signal to be sure that it is indeed stable.