For SSB use this system will probably be OK but you need to think really carefully before using the system on CW, especially if using full break-in. The problem is the switching time of the various relays and how they interact, your two main dangers are:

a) Hot switching, the first CW character is generated before all the relays in the antenna path have closed.

b) Blowing a receiver front end as the first CW character is generated before the receiver dummy load is switched in.

Like good comedy timing is everything here but there is a solution. In 2007 VE2ZAZ published an article in QST titled 'The "At Last!" Radio TR Sequencer' and this might solve your problem. A better solution would be to modify the two rigs so that neither of them can go into transmit until all relays have switched.

Tanakasan

A Story About 'Spies'

Four decades ago before I got my ticket I just had an HF receiver and a longwire running the length of my parent's garden. My father was happy with this but our neighbor, Mrs Clarke kicked up a real fuss because she thought it spoiled the view. One morning I was tuning around and there was a knock on the front door, I heard my father answer and then immediately afterwards an instruction from him to come down RIGHT NOW!!

A police officer looking very apologetic was standing on the doorstep. He explained that somebody had reported that a Russian spy was operating from the house and he would like to come in and look around. So, he came inside, and we all walked upstairs to my bedroom where I had my radio gear.

As the officer walked in to my bedroom the first thing he was was a QSL card from Radio Moscow 

An hour later he left happy and smiling after his coffee and cake supplied by my mother and father. The 'Russian Spy' was never caught.

Tanakasan

To KD8IWZ

"Only 1 time did I decline to sell a motorcycle. I sincerely told the parents I felt their son didn't yet have the coordination to operate it safely and suggested they wait a year or so. They thanked me for my honesty, and a year I later got the sale."

Thank you.

Tanakasan

OK, thanks to WB6BYU and M0HCN for the technical explanations, it looks like I have my answer.

Measure the voltage and current passing through the feeder along with the phase difference between them (if any). From there either use a lookup table or compute the L and C values for a match. What I might do next week is set up a dual beam scope showing the voltage and current waveforms and then experiment to see if L or C has to be increased or decreased for a 1:1 match, if I do this at a low enough frequency the sinewave should be easy to display.

Tanakasan

The main topic of discussion around our radio club at the moment seems to be automatic antenna tuners. One member is building a unit from a local design and the club themselves have the new Elecraft 500W tuner on order. So, we were sitting around on Thursday night and someone asked how one worked. None of us had any idea.

We all know the basic circuit, a variable capacitor on the input or output and a variable inductor in series, fiddle with the values until it transforms your antenna and feeder into something that looks like 50 ohms. But, how do you control L and C given that your only four inputs are the voltage and phase of the forward and return signals? Is there a mathematical formula somewhere that says 'if forward power is W and X and reverse power is Y and Z then do THIS to your LC combination'?

Of course, LDG aren't talking

Tanakasan

Ah! Never having seen one of the wee beasties I didn't know about the metal insert that clamps the wires. So, with the requirement to strain relieve the connections inside a metal box things are a lot safer than they first appear.

Thanks!

Tanakasan

Nothing to do with Ham Radio but I'm curious about something. Over on the European side of the pond if we need to join two mains cables behind a wall then either we use a junction box with terminals or we use something referred to as a 'chocolate block' connector, see https://www.europaspares.com/images/14552/1.jpg

In the USA and Canada something called wire nuts seem to be the norm, looking like the cap on a toothpaste tube they just appear to twist on. Are these devices secure and what happens if the cable is pulled? I'm also interested in the current carrying capacity of the connection with just a twist connection.

My personal preference is to use a junction box which clamps the cable at the insulation and, separately, makes the electrical connection but I'm a belt and braces kinda guy.

Tanakasan

Bit expensive, but if it introduces more people to electronics construction then I'm happy.

Tanakasan

Did the rig come with the manual?

http://www.rigpix.com/icom/ic701_manual.pdf

Tanakasan

"73 Dan (Who considers 'No user serviceable parts inside' to be a challenge)."

Such a label is an open invitation to unscrew the covers and take a peek inside.

Tanakasan

A quick analysis of the big rigs, feel free to disagree or chime in:

Icom 7800
Been going for years, a few initial teething problems that now seem to have been sorted. Nice receiver front end.

Yaesu 9000
More controls than the flight deck of Concorde and I hate the ergonomics with a passion. Other people however swear by 'em. What I do like are the display graphics that show the receiver front end status at a glance and those big meters.

Kenwood TS 990
The unknown quantity, although that LCD above the main tuning control is a good idea.

Hilberling PT 8000
Looks good, nice ergonomics, but they have been trying to get this project to sell for years. Might not be here in 12 months time.

My choice would be the Icom 7800 but the problem is that I don't have the antennas to justify such a rig. It would therefore be a waste of my cash.

Tanakasan

Red right, tab top, all you need to do then is put the right wires in the right holes.

Tanakasan

The only people I know who do kits for 100W linear amplifiers are Communication Concepts:

http://www.communication-concepts.com/

Tanakasan

RTFM (Read The Fine Manual)

If you look at page 5 of the operating manual you will see a list of supplied accessories:

AC Power Supply FP-29 and its accessories (Separate Carton)
Hand Microphone MH-31B8 (depending on transceiver version)
RCA Plug (P0090544)
1⁄4-inch 3-contact Plug (P0090008)
3.5 mm 2-contact Plug (P0090034)
3.5 mm 3-contact Plug (P0091046)
4-pin DIN Plug (P0091004)
5-pin DIN Plug (P0091006)
Operating Manual
Warranty Card

Now, to be fair the manual I'm looking at is for the FT-1000MP Mark-V so I could be wrong here.

Tanakasan

To VK2TIL

Are you sure about that 6400 pf capacitor in the diplexer? Seems awful big.

Tanakasan