On Dec 11, 2024, at 3:50 AM, Dave Riley <[email protected]> wrote:

QSK??

I went out to sea as an RO for a dozen years. It was hard to get a seagoing job because of technological changes so the companies were looking for a few CW operators with communications electronic experience. It was the answer to a kid's prayer. I ended up in the engine room as a troubleshooter when not standing CW watches which meant overtime, nice!

The old-fashioned CW consoles were noisy, chirpy and clunky. I would hear QRQ Russian ships that sounded great on 500 kcs. but with our old American-made radiotelegraph consoles it was not professional sounding. So how to go QSK with three 813s making lots of RF??

Pressing the CW key caused a very large relay to cycle which placed the 600' wire antenna on to the transmitter from the receiver going clunk, chirp, and awful sounding. Especially when using high CW speed.
The U.S. Coast Guard stations in the Pacific were crack troops and 30+ WPM was ops normal.
Now a Yank ship sounded as good as a Rusky only faster and no chirps..

What to do, ummm, imagineering??  I had a LowFer rig on board for many sea going QSOs in the160-190 KC band..

Then it hit me.  Cause the antenna console relay to be permanently positioned in the TX position.. Easy done..

Place the receiver E-probe antenna directly in the field of the kilowatt tank circuit thence direct to the ships receiver.  Voila, clean, no chirp QSK and you can hear between high speed dits, even..

QRU de aa1a/mm,  '1a' LowFer

On 12/10/2024 2:56:05 PM, Roger Graves <[email protected]> wrote:

Hi Paul,

If the termination resistor is 470 Ohm, then 1W dissipation would require 22 Vrms across it. You could put a back-to-back pair of circa 22V Zener diodes across the resistor to limit the dissipation to 1W. A low value resistor in series with the diodes would reduce some of the RFI generated by the Zeners. Capacitance of the Zeners would need to be evaluated.

Just a thought.

73,
Roger VE7VV

> On Dec 10, 2024, at 9:03 AM, Paul N1BUG FN55mf wrote:
>
> OK, here is one I could use some help with.
>
> I am using a large K9AY loop (twice the 160/80m size) for receiving on
> MF and LF. It's the best of any antenna tried so far.
>
> The problem is that LF, MF and even HF RF can get into it in sufficient
> quantity to burn the 3 watt termination resistor and damage the
> transformer! How can I protect the loop components from damage?
>
> Using a relay to disconnect or short something is not an option. I
> cannot run control cable to the loop. Coax is already used for the
> voltage to switch directions on the loop.
>
> What do you suggest I should use to shunt the RF from both sides of the
> loop to ground so components won't get damaged? My first thought was
> diodes (I'm old school) but I'm not sure small ones eg. 1N4148 can
> handle the few watts of RF power and big ones appear to have too much
> capacitance.
>
> Of course I also need to protect my delicate SDR receiver, that's
> another whole can of worms. At least for now I can try to remember to
> always disconnect it before transmitting.
>
> 73,
> Paul N1BUG
>
>
>
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