In case you look at the output waveform on the 1.Seventy five - 2.Zero vary, you will discover that L51 resonates to 80 meters. The basic ranges of the 250-122 VFO are 1.Seventy five - 2 MHz and vapetank 7.0 - 7.425. Eleven meters can be modified to cover both 5.05 - 5.075 and/or vapemalluk 6.02 - 6.056 MHz with the addition of a mica padder capacitor in parallel with C56. The first scope photograph reveals that the VFO signal at the 6AU6 grid comes on earlier than, and persists long after, the sign on the 6146 grids.
It consists of R55 (22 ohms) directly on the grid of the 6AU6 oscillator tube to cease VHF oscillation above eighty meters. I avoided this by leaving R13 as originally purposed for vapemalluk the bleeder and clamp tube circuits, and add a devoted (inexpensive) 22K 10 watt to operate the separate 807 display regulator. Adding a cargo door (e.g. one which was proof in opposition to vacuum) would add to the cost. I didn't observe this downside, however you'll be able to add a 330 ohm 1 watt resistor ejuiceuk in sequence between the two VR tubes if this occurs.
C8 screen bypass is a good suggestion, doesn't overdo it, and eliminates the need for vapebestuk VR tubes.
Choose the cathode bypass capacitor on V1 to suit your preferences. The 6AQ5 driver wouldn't want a coupling capacitor or feed resistor in that case. This gives a a lot steadier load impedance offered to the audio driver. Absolutely nothing extra is needed, since you will have already fixed the true downside in the 6146 display screen provide and the HV dynamic impedance.
The 6C4 plate impedance will not be low sufficient to provide undistorted class AB2 operation from the 807s. However, its transconductance is simply 2200 micromhos, and lacked sufficient achieve to work with quite a lot of D-104 heads. Depending on the driver transformer you select, it is best to sweep the audio response to check it, vapekituk and listen to your signal on a remote SDR like the K3FEF net site to confirm your work. I'm not throwing rocks at different individuals's work right here, simply offering explanation why I took a distinct path.
The 807 screens must solely be powered in the next condition: 1.