[Boatanchors] Re:One Tube QSK Box

[Ed Tanton]

Hi (again) Bill... no problem... with my NOS/NIB Fichter Transtenna 102 T/R 
SW, NOS/NIC Dow DKC TRM-1, plus others, I THINK have close-to one of the 
best T/R SW collections <http://www.qsl.net/n4xy/accessories.html> around 
(still need the band-switched B&W).

Liking them a LOT for BA stations, I am very familiar with them. There are 
several excellent HBK designs... I'll either scan them, or draw them, and 
get you the info.

Scott was pretty much spot-on with his short operating description. Here's 
a couple of other facts. The cable distance between the TX and the T/R SW 
needs to be as short as possible-preferably < 3 ft. Dow solved that in the 
DKC series but building a somewhat simpler device intended to be mounted 
directly on the back of the TX (requires a double male adapter.) The TX is 
left in an enabled state, unkeyed, of course. When the T/R SW senses RF, it 
cuts off the RF to the RCVR-not blanking it... so they really are designed 
for CW. You will be able to hear your own signal that way.

The nicest thing about T/R SWs is that it is the best breakin you can 
have-short of a very elaborate high-speed relay keying setup, requiring the 
independent timing of at least 3 of the relays. No thanks!

There are a couple of undesirable characteristics of the T/R SW. First, 
that they are effectively placed in parallel with your TX tank/output 
circuit... so there can be a condition called "receiver suckout" if you try 
to listen to a different band from the one the TX is tuned to. A couple of 
T/R SW have bandswitching (the B&W I mentioned, and the Fichter.) This 
apparently eliminates the problem. So does something like my Grimm 8103 
HF-Multicoupler. I can listen quite satisfactorily to any HF freq I like 
with no discernable difference between TX band, or not.

Second: you MUST use a low-pass-filter. They can generate some harmonics 
during TX. I have never had TVI using one, but I have always had at least 1 
LPF in-line... TWO if using an amp (one after the TX and one after the AMP.)

I'll get this compiled, and get back to you.


73 Ed Tanton N4XY <n4xy@earthlink.net>

Ed Tanton N4XY
189 Pioneer Trail
Marietta, GA 30068-3466

website: http://www.n4xy.com

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