Thanks for your thoughts, everyone-

I think I may have to check into the performance of my 1/4 wave some more, and consider the dual-1/4 wave, even if it's not truly omnidirectional.

W8JI has given me the background for what I'd thought true all along -- that fender mounting my 5/8 wave would have some drawbacks - I see two of them mentioned here:

- off-center groundplane, which I don't have right now with the center of a 4' x 5' metal roof as a groundplane. I might have a problem with groundplane once I moved to the extreme side of the vehicle right against the fender.

- radiation point would definitely be at the same height as the 1/4 wave, or maybe even slightly lower.
Paul is correct that it may work as well as the 1/4 wave at the roof height for that reason.

So that solution would solve my height problem, but would possibly leave me with the reduced repeater quality-of-signal that I get with the 1/4 wave.
Should not be hard to try and find out, though.

Turns out I don't have stake holes in the truck! I thought there were some down underneath the bedliner, but there aren't in the Frontier.
I can mount something back there though, as a test.
Just makes life challenging when I'm trying to carry a load of lumber or plywood - one more thing to worry about the load damaging..

Errrmm... Huh??

I'm not at the level of antenna work to know how to run complex design and modelling software and so on..

Are you saying that I could simply mount two 1/4 wave verticals front and rear of the roof, and use a T connector in between them, and it'd appear to the transmitter as the correct impedance and resonance?

I can see how there'd be a pattern (evidently forwards and backwards?) resulting from two verticals like that..
Which might be OK..

All being considered, I guess I should probably just try mounting the MFJ in a stake-hold and seeing how that actually does.

I am operating on an urban legend of sorts that the cab of the truck will seriously interfere if it's between the repeater and the antenna...

My immediate impression from the mountain area I live in is that the 2dB is being added to/subtracted from by terrain
by quite a bit.

Depending upon where I am, the 1/4 wave either performs so well that I and other parties on the QSO can't even tell the difference, or
I've gone down into a valley far enough that the 1/4 wave really doesn't cut it.

Those valleys, of course, aren't great performance even for the 1/2 wave MFJ, but if propagation and other factors (repeater site intermod)
are normal, I can still be heard clearly enough with the 1/2 wave, at the full output of my radio, which is 60 watts.
If intermod is up to abnormal levels at the repeater site, there are a lot of folks who don't make it in from the valleys, and that's just life here.

The lab-conditions effect of the  2dB difference doesn't seem to be completely linear out in the field, which is  I guess, expected, given that it's not "the lab"

WB6BYU --

Isn't it possible to make 1/2 and full wave DDRRs?

I have heard that the DDRR is less efficient compared to an antenna of it's same wavelength - and it makes sense too.

I'm wondering if I were to make the thing longer than 1/4 wave, it'd perform better.
I think it's certain that a 1/2 wave 146Mhz DDRR won't perform as well as the MFJ 1422 at 1/2 wave all by itself.

But if it will improve over a 1/4 wave vertical, I might have something. Depending upon just how ferociously ugly and wind-resistant the thing is!
While I'm an engineer and not overly given to vanity and how my truck looks, I suspect there _are_ some limits on just how far I want to go with
weird looking assemblies strapped on the roof rack  ;-)

I probably should have mentioned that with the 1/4 wave, I actually don't even make a couple of my commonly used repeaters
on my drive to and from work and other locations.
A little noise and less than full-quieting I could handle.
Not even being intelligible and having people ask me to repeat things isn't all that nice for them.

I don't mind a bit of a whang when entering a garage - it happens with the 1/4 wave, and it's just the last inch or so.
It'll survive for years that way.
But, I've seen garage attendants come out and check overhead lights and hanging signs for damage after I've gone by, so I don't want to be blamed for some damage I might not even have done, someday...

That's right ---

I remember having looked at one of those for 20 meters back in the day, for mobile use with my TenTec Triton IV

I'll check around.

I'm equally interested in something like four 1/4 wave verticals on the four corners..

thanks

Hi all you Antenna Elmers out there--

Antenna design question for you-


How can I build a low-profile high-performance antenna for mounting on a truck roof rack?
Lower than 1/4 wave high from the rooftop...

I have a midsize pickup truck - a Nissan Frontier crew cab with a full size roof racks on it.

I have a 2 meter rig in the truck, and a fold-over MFJ-1422 on the roof.
http://www.mfjenterprises.com/Product.php?productid=MFJ-1422

In the course of my work, I'm in and out of parking decks all the time
and I'm always folding the thing over, or sometimes not bothering and just
not being on the air for days at a time.

I've tried a 1/4 wave (also MFJ) on the roof, and
since I live in the mountains, performance is a good bit less than optimal.
There's a significant difference in how I make repeaters between
a 1/2 wave and a 1/4 wave...

Obviously, the best thing is simply more metal in the air.

The only thing I can think of to do is to find some
low profile but multiple elements design.
I'm happy to drill/mount whatever on the roof rack. Truck has 126k miles, so I'm not looking for something perfect.

I've heard that mounting an antenna on the bed, say in one of the stake-holes or the hitch
would work, but has some downsides when the repeater is through the cab in front of the truck, and half or more
of the antenna is blocked.

So I'd like to find a roof-top solution, if there is one.

Any ideas?

Can I feed four 1/4 wave verticals mounted onto the roof rack?
A loop??

Thanks!

Well, that about proves that I'm wrong for thinking it was an Autek...  ;-)
I should have thought of checking the reviews on here..

And it's a bit of serendipity that you posted that second link -

I'd seen that before, and been fascinated by it -
Now, I might just buy two of them and do that myself..

It's not like I'm going to find that old filter of mine, I've just been curious as to what it could have been --

I may have misled folks by mentioning Autek in the subject line of this thread - it's now really quite likely that
it wasn't an Autek, and I'm mistaken..

Who did make it, is a mystery... I'm pretty sure it was not homebrew - if it was, someone
did an awesome job of lettering, since I do recall the printing and assembly looking very factory screen printed and professional assembly.

Thanks for the article on dueling Auteks.. might go there...

'fraid it's not a set of headphones..

I'm starting to wonder if it's not Autek --
I just honestly cannot remember who made it.

It's a piece of equipment that went between your rig and a speaker, as I recall -

Probably single RCA in/out jacks on the back, a few knobs were on the front,
maybe an LED or two...

Not quite the CO-3, perhaps the 3M --
Definitely that style of case, although maybe not that manufacturer,
although the picture at the bottom of the page was bang on, if a bit deeper..
seems as best I recall that the width and depth were about the same?


I should amend this by commenting that
the unit, best recalled, was about 2"- 21/2" high, about 4" wide, and maybe 4 or 5" deep.

About the same size as many keyers, etc.

No meters of any kind -- just one LED or maybe two, and three or four knobs and a couple of switches..

Powered directly off 110v as I recall

Thanks! you made me realise I could post a few more details...

Hi all --

Does anyone have any of the older 70s era audio filters??

I'm trying to recall what something was that I had --
I don't have a model number, but looking through the possible manufacturers, it seems to ring a bell that it might've been an Autek Research

It did not have the newer square case ones, like the QF1

Mine had the old 60s style round corners, and the type of case that slid over the
front and rear panels so that both were recessed inside edges of the case.
Both panels had rounded corners, as did the main case.
Real 1960s-70s styling...

Also had the perforated metal type case, where the case had 1/8 inch holes punched into it all over,
not the more modern slotted style vents.

Does that ring a bell with anyone??

Edited to add:

I should amend this by commenting that
the unit, best recalled, was about 2"- 21/2" high, about 4" wide, and maybe 4 or 5" deep.

About the same size as many keyers, etc.

No meters of any kind -- just one LED or maybe two, and three or four knobs and a couple of switches..

Powered directly off 110v as I recall

Thanks! you made me realise I could post a few more details...

73, de Tim

Thanks folks!

I'll have to check out CW Skimmer -- sounds like it's what I'm after --

That, and it answers the one question I'd had -- what interface?
I was hoping for something that used that sort of basic standard cabling.

Now I'll have to get one of the PCs in the office tied into the shack on the opposite side..

Thanks!

I should probably add that I use a Ten-Tec Omni IV, a Swan 350 (not seriously for CW, though)
and a Yaesu FT-757GX.
Mainly the Ten-Tec
(after all, if you have a Ten-Tec, why would you use anything else for CW - )

I don't have any of those fancy new rigs with all kinds of digital interfaces and the ability to control the International Space Station on some multi-pin connector on the back of the radio...

I _am_ however, an IT professional, and one of the extremely early adopters of open source

So if there's a GPL program, I'm open to it...

That makes sense.

If what you're after is website access to your hosts' webservers, and use of their Internet and other such resources, you probably don't need a trust to accomplish that. Proper configuration of DNS and firewall/server access permissions would take care of a lot of it, without resorting to a full trust or one way trust.

Trusts are primarily used when you absolutely have a reason to use direct AD authentication to access the resources for some type of auditing or regulatory compliance reason, or you have hundreds or thousands of accounts on each "side", all of which need NTFS access or AD-controlled access to applications in the "other" network.
It's not necessarily often done for simply allowing access to non-public web servers on one side, or for access to email servers, etc. A lot of that can be done via other means.

For a lot of other types of resource sharing, it's possible and often more commonly done to accomplish those same types of access using locally configured logins on webservers, etc, and users simply need to log in using a different account when and if they try to use that resource from the 'other' network.
It typically depends upon just how many users will really be accessing cross-domain resources just how often, before a trust is used.

You might try playing around with a one-way trust, to see if their larger environment can be told to trust your side, but you aren't going to be trying to configure your SBS server to also allow unrestricted access to every one of their users.
Microsoft might well alllow that sort of thing for SBS,which sounds like it might need your needs.

But, don't let me talk you out of a trust -

Let me get back to you about non-profit access to TechSoup and other resources-- we might be able to find you some seriously cheap licenses, which may help your rationale for Server 2008.

Hi all -

I'm looking to find out what the second best method of decoding Morse code is -
ie, what are the current methods that would use a computer?

I say second best, because I know the BEST way is with the built-in OEM stereo listening system, after appropriate training is applied... ;-)

I'm posting this here instead of the CW forum because over here, maybe the flames of "you could always just copy it using your EARS" won't be quite 95% of the responses I get  ;-)

I'll further qualify this by saying I've been a General since the early 80s, and can actually copy the required 13wpm.
I'd just like a little help sometimes...  ;-)

So -

I know there are several programs, and many types of interfaces...

I just don't know what's the most recently developed and what's considered best by the user community
as opposed to the marketing efforts of those who have something to sell today... 

What do you folks use?

thanks KA4LFP