Well, if you want to be heard, and not collect OO cards for 2nd harmonic radiation, I would stick to a coax fed dipole, and use the KJ4KV tunable auto transformer arrangement.  Absolutely no mods needed internal to the transmitter, I built mine on a small piece of 1x4, appropriately painted OD, and it sits next to the transmitter with small
Insulated wire connections to the command set antenna relay box antenna connection and the transmitter chassis.  If you use a very short antenna as was used on an aircraft, you will likely radiate very poorly, even with some radials.  Can we say Gotham Vertical?  If you use something like the current antenna dujour end fed half wave, it by itself will have a very high feed point impedance, and will not be a good match for the low impedance output link coupling of the transmitter.  And just using a series cap after the link will not provide any significant suppression of 2nd harmonic energy.  Using a multiband doublet with open wire feeders without some sort of tuner will also present  a high feed point impedance that will not be a good match for the low impedance link coupled output design.

73 de

Chris AJ1G
Stonington CT.

Sent from my iPhone

On Aug 9, 2023, at 11:37, [email protected] wrote:


Ray,
 
Are you using this setup in the field? If so why don't you simulate the antenna installation on a plane? Feed an end fed wire and simulate the plane body with radials? See if you can get an output using the original tuning components.
 
Mike N2MS
On 08/09/2023 11:23 AM EDT Ray Fantini <[email protected]> wrote:
 
 

In a world of Pi output tanks, I know that the Old School approach of an Inductive Link tank is not cool, but if you look at the original design of those transmitters that’s what they designed them around and keeping this in mind I did what the old nineteen sixties ARRL Handbook recommended I am just using the output of the link tank with no loading coil directly, will try playing around with series capacity and see if there is anything that can be picked up that way but wanted to keep this simple with a minimum of modifications. I know most modify the transmitter for cathode keying but wanted to also keep all that original so installed on the rack panel is a high voltage relay that keys the HV on and off for keying the transmitter. Using a choke input filter and only 8 micro farads yelp is held to a minimum, also have a VR tube regulator on the oscillator feed that helps keep some form of load on the HV supply when not keyed to keep the capacitor of charging way up from the power supply being unloaded. Because big value capacitors are no longer a big deal everyone now days builds a lot of filter capacity in there HV supplies and think in some ways that adds to the problem of frequency stability when keyed but with this minimal filter find the transmitter keys just fine and has no detectable AM noise.

There is a lot you can do to make this a better transmitter, but in some ways just like using the old HRO receiver in its original configuration the challenge of doing things working within the confines of original design can be fun.

Have considered ditching coax entirely on this set up and running open wire to an end fed Hertz, at some point want to kick around the idea of a small shed or out building located away from the house, shop and all that with just Old School radios and an open wire feed system.

 

Ray 

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