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The "Take-it-wth-You-Anywhere" VFO Power supply.




 
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Author Topic: The "Take-it-wth-You-Anywhere" VFO Power supply.  (Read 3128 times)
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DMOD
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« on: October 29, 2014, 09:38:12 PM »

The "Take-it-wth-You-Anywhere" VFO Power supply.

Updated 11/24/14.

The value of DZ1 was changed to mitigate a chirp on unkeying.

* General VFO Power Supply.pdf (52.4 KB - downloaded 122 times.)
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Pete, WA2CWA
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« Reply #1 on: October 30, 2014, 02:54:46 AM »

The keying lead is also brought out through the octal plug of he HG-10. If running the outboard PS with the VFO with different transmitters, that lead may also have to be used. As was found when trying to use the Johnson 122 VFO with a variety of different transmitters, and depending on the crystal oscillator circuit in the transmitter, it sometimes required some additional components in the oscillator circuit. Heat and limited mounting space in many VFO boxes would make me very carious with an inboard PS. The Hammond transformer must be made of gold or I'm way out of touch with transformer prices. Also, on the third schematic, you mention HA-5 VFO. That already has an inboard PS.
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« Reply #2 on: October 30, 2014, 12:34:45 PM »

The transformer is mounted externally on the back of the VFO's chassis to avoid hum modulation of the oscillator, which was the implied transformer location.

How you key it is up to the operator and you need to look at the VFO circuit to determine your jumpering options.

In my case, I use the external keying option with a solid state keying sequencer:

The keying sequence is:

1. short receiver input (I use a ricebox receiver most of the time with a Knight R-100 some of the time)

2. key linear

3. key DX-60

4. key VFO

The unkey sequence is 4, 3, 2, 1.


 

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