Junk box.

[KA5PIU]

Hello.

Hams have them, that parts supply with parts from who knows what.
But, where do you get the parts? everything is is so application specific, right?
Well, for starters, microwave ovens have this wonderful HV supply, DC even!
But, there are other sources.
One apartment complex had four cordless electric lawnmowers that they were junking.
I just had to take a peek. :mrgreen:
Inside two are 24 volt Li-Ion packs and the other two have NiMH packs.
The charger on three are the same, just a jumper setting for battery type.
The electric motor in each one is the same.
After a bit of work I was able to remove the motors, each one is fine.
The battery packs are defunct but everything else works.
So, I converted two to corded electric power, not that I do not have enough mowers. :mrgreen:
One of the chargers I am using as an aircraft NiCad or lead acid 24 volt charger, switch selectable.
The other three are junk box items at this time.
But, so far everything has been free.

[12Footer]

I found a cordless drill on the side of the interstate today. The case is toast, but -- I'm thinkin "homebrew screwdriver mobile antenna" some day. :monkeydance:

[N8YX]

I found a cordless drill on the side of the interstate today. The case is toast, but -- I'm thinkin "homebrew screwdriver mobile antenna" some day. :monkeydance:
Get the 7th edition ARRL Antenna Compendium - two "screwdriver" construction articles featured therein.

FWIW: There was an entire truck load of new, 12v cordless high-torque screwdriver sets offered for sale at a local motorcycle swap meet a couple years ago. Price, including set of bits: $1.50 per kit.

[N2CHX]

Price, including set of bits: $1.50 per kit.

Wow, that's CHEAP! My bits just went for about $10,000.

[KG4CGC]

:rofl:
Wow, that's CHEAP! My bits just went for about $10,000.:rofl::rofl::rofl::rofl:

[N4VGB]

I found a cordless drill on the side of the interstate today. The case is toast, but -- I'm thinkin "homebrew screwdriver mobile antenna" some day. :monkeydance:

Screwdriver antenna = air cooled dummy load that just happens to very slightly radiate RF.

Military whip with autotuner located at base, the only way to fly.

[N8YX]

Military whip with autotuner located at base, the only way to fly.
'WIK's test-range evaluation of a base-loaded arrangement like you describe says otherwise.

As do my experiences.

A whip/tuner combination works well at the resonant frequency of the whip but as you go lower in frequency the losses go up. In some cases, way up.

[KC2UGV]

Screwdriver antenna = air cooled dummy load that just happens to very slightly radiate RF.

Military whip with autotuner located at base, the only way to fly.

Military whips are pieces of 吹牛・吹牛. The splinter and crack constantly, and even the vhf ones are worse than 廢物・废物, because they detune constantly while driving, killing the finals in the rigs.

[N4VGB]

Military whips are pieces of 吹牛・吹牛. The splinter and crack constantly, and even the vhf ones are worse than 廢物・废物, because they detune constantly while driving, killing the finals in the rigs.

Oh BS Corey, you can't even build a 20m dipole that works worth a crap!:rofl:

I've used a Shakespeare fiberglass military whip with an Icom tuner at the base for years. Mounted to an ARA fiberglass bed cover shell on a '93 Chevy 4WD truck. 16ft and tied down to the front bumper in NVIS configuration while moving, add the larger base sections while parked for 32ft total.

The only real problem is if someone is operating it on 160m while parked, the RF voltage is real high at the exposed 4 ga hard drawn copper wire connecting the base of the antenna to the tuner inside the shell. It'll eat your arse alive at the base while xmitting. Hands off dummies!:rofl:

[N4VGB]

http://forums.hamisland.net/images/misc/quote_icon.png Originally Posted by N4VGB http://forums.hamisland.net/images/buttons/viewpost-right.png (http://forums.hamisland.net/showthread.php?p=222650#post222650)
Military whip with autotuner located at base, the only way to fly.



'WIK's test-range evaluation of a base-loaded arrangement like you describe says otherwise.

As do my experiences.

A whip/tuner combination works well at the resonant frequency of the whip but as you go lower in frequency the losses go up. In some cases, way up.

Did you know that I can't do a "Reply with Quote" to any of your posts???

I do a lot of things differently from what the "antenna experts" say to do. I don't believe in tuners in the shack at all or at the radio in mobile use. A tuner, to work at it's best, belongs at the actual feedpoint of any antenna. That isn't practical for many installations, but it is very practical to use open wire feeders for any home antenna and use coax to only feed the tuner.

With a tuner in the shack you're tuning your coax run as part of your antenna and it will assuredly radiate RF on some frequencies, even if the antenna is cut for single band use.

[KC2UGV]

Oh BS Corey, you can't even build a 20m dipole that works worth a crap!:rofl:


lolwut? It's working fine. Of course, if you are referring to my experimentation, of course some things will not work, and others will. That is the purpose of experimentation.



I've used a Shakespeare fiberglass military whip with an Icom tuner at the base for years. Mounted to an ARA fiberglass bed cover shell on a '93 Chevy 4WD truck. 16ft and tied down to the front bumper in NVIS configuration while moving, add the larger base sections while parked for 32ft total.

The only real problem is if someone is operating it on 160m while parked, the RF voltage is real high at the exposed 4 ga hard drawn copper wire connecting the base of the antenna to the tuner inside the shell. It'll eat your arse alive at the base while xmitting. Hands off dummies!:rofl:

I talk from experience. Those pieces of fei oo couldn't stand being used in action, and I had the pleasure of replacing/repairing them. Never used so much fiberglass repair kits in my life.

The HF stationary ones were a bit better, but one good wind and **SNAP**. There went the elements. More fiberglass repair kits, or ordering another. I ended up keeping about 5 of the VHF mobile whips and 25 elements for the HF stationaries in stock while in Iraq. And that was just for a Squadron level.

[N8YX]

I do a lot of things differently from what the "antenna experts" say to do. I don't believe in tuners in the shack at all or at the radio in mobile use. A tuner, to work at it's best, belongs at the actual feedpoint of any antenna. That isn't practical for many installations, but it is very practical to use open wire feeders for any home antenna and use coax to only feed the tuner.
The 'experts' tested exactly what you described - that is, a random-length whip with the tuner directly at its base.

Simple physics - the lower the frequency...the shorter the whip (electrically)...the more the impedance goes up. Which necessitates a larger inductance to match. The efficiency of a shortened radiator decreases as frequency decreases - this being due to increased radiation resistance - and the matching network (or base-loading coil) dissipates more and more of the applied power as heat.

Conversely, a vertical whip which is an electrical 1/4w or longer at the frequency which it's being excited with will work decently - to a point. Make it much longer than one wavelength and it'll act as an end-fire radiator, not an omnidirectional one.

The only "practical" reason for using a shortened whip/tuner arrangement is that it permits rapid, remote-controlled antenna matching under field conditions...the radio which interfaces to the tuner can be set up to command the tuner to match its load, thus removing the operator from the equation. Changing radiators (or resonators) based on operating frequency is also taken out of the equation, so a thorough understanding by the operator of the logistics involved isn't required: They key the mic and the transceiver/tuner does the rest.

That said - I have a Cubic remote autotuner that outputs to a random wire. I have to build a control cable for it and then I'll deploy the arrangement with an inverted L or some sort of vertical radiator. The rig which it's designed to be used with covers 1.5-30MHz continuous, and the tuner can be preset to match several "bands" within that range.

[N4VGB]

The 'experts' tested exactly what you described - that is, a random-length whip with the tuner directly at its base.

Simple physics - the lower the frequency...the shorter the whip (electrically)...the more the impedance goes up. Which necessitates a larger inductance to match. The efficiency of a shortened radiator decreases as frequency decreases - this being due to increased radiation resistance - and the matching network (or base-loading coil) dissipates more and more of the applied power as heat.

Conversely, a vertical whip which is an electrical 1/4w or longer at the frequency which it's being excited with will work decently - to a point. Make it much longer than one wavelength and it'll act as an end-fire radiator, not an omnidirectional one.

The only "practical" reason for using a shortened whip/tuner arrangement is that it permits rapid, remote-controlled antenna matching under field conditions...the radio which interfaces to the tuner can be set up to command the tuner to match its load, thus removing the operator from the equation. Changing radiators (or resonators) based on operating frequency is also taken out of the equation, so a thorough understanding by the operator of the logistics involved isn't required: They key the mic and the transceiver/tuner does the rest.

That said - I have a Cubic remote autotuner that outputs to a random wire. I have to build a control cable for it and then I'll deploy the arrangement with an inverted L or some sort of vertical radiator. The rig which it's designed to be used with covers 1.5-30MHz continuous, and the tuner can be preset to match several "bands" within that range.

Hey now! The "reply with quote" works on your posts now!

Anyway, I typed a nice long technical reply to your post and when I posted it, I was no longer logged in and it was gone, happens a lot lately.

Since I don't care to type it all again, screw it.

[KU0DM]

Hey now! The "reply with quote" works on your posts now!

Anyway, I typed a nice long technical reply to your post and when I posted it, I was no longer logged in and it was gone, happens a lot lately.

Since I don't care to type it all again, screw it.

Did I just see someone take the easy way out? :lol:

[N4VGB]

Did I just see someone take the easy way out? :lol:

No you just saw someone becoming very tired of the new software or ???? tossing me out at times while I'm typing long responses to posts, but somehow I can leave the keyboard for a long time and come back with no problem, still logged in just fine.

The mystery in no way relates to how many users are online, very strange.

[kb2vxa]

Checking the "remember me" box puts a cookie in the cache, try it.

[N4VGB]

Checking the "remember me" box puts a cookie in the cache, try it.

It wouldn't matter, cookies get eaten quickly here anyway, cookie eating software.

I've started opening notepad every time I make a very long post or reply. When I'm initially tossed by the system, what I've typed is still there and can be quickly copied to notepad. It's when I log back in that everything I previously typed disappears.

So whatever the problem is, it's no longer a problem.

[KB3LAZ]

Meh, I get logged out while typing a lot too. Then again if it is a long response I copy it first in case this happens. I learned to do this long ago when I had the same problem on the zed. Clicking the box makes it last another few minutes most of the time.