Proper Length of Antenna and Other SSB Questions

[btrayfors]

OK, hopefully, a picture is worth a thousand words:

[gchabs]

Bill and everyone else who responded, thanks. Bill, thanks also for the picture, it helps explain it all. I haven't accessed the back of the radio in several years, since I first installed it and the tuner on my boat. I had a instructions back then - from the previous owner of the radio and tuner -which told me how to connect the various wires. It also indicated that I should attach copper stripping from the radio to the tuner. So, I must presume, in light of what you folks have indicated, that the installation instructions I had were less than optimal. Most notably, I don't remember any red and black wires that were part of the cable connecting the tuner to the radio (cable #1), and which I had to connect to a separate power source. When I get to the boat, the instructions in this post will be very helpful in making sure I have the right connections.

Just to round out my knowledge on this subject, I'll ask one last question, then leave you folks alone. If the red and black wires from cable #1 were not connected to a power source, do I take it that I could nevertheless transmit and receive emails; and have some, albeit very limited ability to communicate by voice? If so, then that probably explains my issues. If not, then I presume the rest of the steps I intend to take, should help address the problem. Once again, thanks to all. George

[btrayfors]

George,

In response to your 'last question', the answer is a definite maybe :-)

The red and black wires supply power to the tuner for its use in changing the impedence -- that is, in providing a 50-ohm load to the transceiver. That's what it is looking for, and will be the lowest SWR. When there is no power to the tuner (like you forgot to connect the wires, or to turn on the 12VDC power), the tuner will not tune. It will remain in an untuned state.

Usually, this is a 'through' state, where the tuner effectively takes itself off line and passes the signal from the radio directly to the antenna. In the untuned state you can still receive pretty well, and you may or may not be able to transmit a bit depending on the frequency band you are using and the impedence presented by the antenna and feedline on that frequency band, and how high the standing wave radio (SWR) is on the feedline.

With anything more than a low SWR, the transmitter will automatically cut back it's power output in order to protect the final transistors, so you could be putting out very little power.

But, under certain conditions, it's possible to cover long distances with just a few watts. I've worked over 10,000 miles with just 2.5 watts, but that was almost a freakish occurrence. It's NOT what you want to do.

What you do want to do is have the SG-230 do its job of coupling the antenna and ground system to the radio, so that you will radiate maximum power on transmit. The SG-230 is a very capable tuner...actually, IMHO the best there is on the market these days...and it can tune practically anything.

But, you have to give it a chance to work by providing it 12VDC power.

Bill

[Paul Elliott]

From reading the specs, it looks like the tuner will be in a "bypass" mode when it has no 12V power connected (can anyone confirm this?) If so, then your transceiver will be directly connected to the antenna. On some frequencies this will perform fairly well for both transmit and receive. On others, it will probably receive adequately, but your transmit power will be *very* low.

As for being able to send emails vs poor voice operation, it's all going to depend on the frequency, time of day, the path to the other station, and your antenna. Either mode may or may not get through, and it has little to do with voice vs email.

[btrayfors]

Originally Posted by Paul Elliott

From reading the specs, it looks like the tuner will be in a "bypass" mode when it has no 12V power connected (can anyone confirm this?) If so, then your transceiver will be directly connected to the antenna. On some frequencies this will perform fairly well for both transmit and receive. On others, it will probably receive adequately, but your transmit power will be *very* low.

As for being able to send emails vs poor voice operation, it's all going to depend on the frequency, time of day, the path to the other station, and your antenna. Either mode may or may not get through, and it has little to do with voice vs email.

Paul,

Yes, it's supposed to go into the bypass mode, and it usually does. However, over the years (and I've used mine for over 23 years) I've noticed that it sometimes doesn't seem to be in a bypass mode at all with the power removed!

What you said about what would transpire is exactly what I said...a definite 'maybe' to George's question :-)

Bill

[Paul Elliott]

Hi Bill (you and I should get together over beers sometime),

As usual, we were each composing our answers at the same time. You obviously type faster!

I couldn't tell from the schematics, but does the tuner use latching relays? This is pretty common, and I can see how they might not get reset when powering down.

[PamlicoTraveler]

This is a great forum!

[Paul Elliott]

Originally Posted by Paul Elliott

I couldn't tell from the schematics, but does the tuner use latching relays? This is pretty common, and I can see how they might not get reset when powering down.

Actually, the schematics do show that the relays are non-latching (I had to look at the relay-driver electronics on a different page). Unless a relay has spot-welded itself closed, I'm pretty sure that the tuner *will* be in bypass mode when it's got no power.

[btrayfors]

Originally Posted by Paul Elliott

Actually, the schematics do show that the relays are non-latching (I had to look at the relay-driver electronics on a different page). Unless a relay has spot-welded itself closed, I'm pretty sure that the tuner *will* be in bypass mode when it's got no power.

Paul,

Well...yes and no.

While it is possible to receive signals with no power applied to the SG-230 tuner, typically they will be greatly attenuated.

SGC describes the 'pass-thru' or 'bypass' mode as 'stand-by' mode. The tuner only enters the 'stand-by' mode when 12VDC power is applied.

This is readily verifiable in any setup where you can control the 12VDC feed to the tuner. In my case, I have a toggle switch to supply power to the tuner. You can turn on the radio, listen to signals and, when you flip the switch, the signal strength of incoming signals is noticeably greater.

However, no tuning takes place until RF is supplied from the radio. Then and only then does the tuner work toward a full match, where you will have the greatest strength of incoming and, especially, of outgoing signals.

Hey...the beer sounds good. Your place or mine?

:-)

Bill
WA6CCA

[Paul Elliott]

Originally Posted by btrayfors

Well...yes and no.

While it is possible to receive signals with no power applied to the SG-230 tuner, typically they will be greatly attenuated.

SGC describes the 'pass-thru' or 'bypass' mode as 'stand-by' mode. The tuner only enters the 'stand-by' mode when 12VDC power is applied.

Ah, yes, I see it now. The tuner is a switched Pi-network, and all the relays are normally-open. Without power, the multiple input and output shunt capacitors will be disconnected, but the series inductor chain will be at maximum inductance (the powered relays short out the individual inductors in the chain).

For some reason I had assumed that the inductor relays would be normally-closed. Bad assumption.

So, the unpowered tuner will be introducing a large inductance in series with the antenna. This will generally not result in an optimum match(!) You might be able to make some contacts though.

[gchabs]

Once again, thanks for all who contributed. Can't wait to see what happens when I apply power. Speaking of beers, if you are ever in the Richmond area or near Deltaville, give a shout. I'll buy. George