Remote VFO - Knight V-44

Everyone needs a remote VFO from 1955

Note to self: Never browse eBay just before you go to sleep

 This 1955 remote VFO was unique because it had a built-in power supply.  It's also interesting that its base oscillation frequency is in the 160m band.  It takes that frequency and multiplies it for each subsequent band (x2 for 80m, x4 for 40m, etc.)  That means it also multiplies the drift.  Specicified drift is 300Hz an hour.  That doesn't sound too bad, but multiply that by x6 up in the 10m band and holy-smokes, it's drifting 1800Hz an hour.

That's gonna make operating CW like a game of chase, or hide and seek after every exchange.

This is gonna be fun.

Surprisingly the big dial is actually operating the variable cap through a reduction gear and it's very smooth

Uses 4 tubes. Power supply up top, VFO circuits in the bottom to minimize impact of heat from the PS.

Power supply

old electrolytic power filter cap  must be replaced

10k 7watt resistor had failed

Replacement bits

The 450v electrolytic cap must be replaced for safety reasons. All the other components measured within 10% of specifications except for the 10k 7w resistor connected to the OA2 tube. It had
gone up into megaohms of resistance, which is likely when the VFO was taken out of use.

Handwritten notes inside the chassis indicated the VFO tubes had been replaced in 1977. Until I get the replacement parts for the power supply I won't know the condition of the tubes.

Plans

I plan on using this with a Homebrew transmitter that I may build sometime this summer.

Surprisingly, it outputs 10 volts of signal, so I may also build an output filter and use it as a QRPp transmitter on its own.

Lastly, it can also serve as a signal generator, albeit one rich in harmonics.

The possibilities are endless.


That's all for now .

So, warm up your Tubes and spray some RF into the air.

73
Richard ,AA4OO