Batboard

Howdy

A friend of mine just got himself a UHF HT1000 - unfortunately, the seller sent an 800 dipole rather than a UHF whip, stating that's what it came with when he got it at auction in a box of miscellaneous crap.

Until we track down another UHF antenna, how safe is this thing to use on UHF? Receive performance seems to be excellent, but I'm not sure about transmitting.

Cheers

Receiving is not as critical as is transmit.

An incorrect antenna can blow out the PA stage in the Jedi transmitter due to a mismatch and reflected power back into the PA.

I would not want to risk dammage to the radio, DO NOT TX with the wrong antenna.......

Yeah, I don't want this thing to blow up. But I also guessed it might, if we're lucky, resonate on 400 and be safe for a week at QRP until the UHF antenna gets here.

There is ONE 800 antenna that does work well on UHF, and it's the 'standard' whip antenna that could be found on most SMA ported radios such as the MTS2000, HTX and so on, they look like a regular whip with the distinctive 'ball' on the tip.

The lower sleeve of the antenna also has embossed on it:

Motorola 800

This is the same length whip as the factory standard UHF whip and I've been using one on my own UHF HT1000 for two years and on the service monitor and Bird, I get a pretty flat response curve that rises slightly at 439, then dips through to 452, then rises again to about a 1.6:1 ratio and stays within this rage up to 464, then it shoots up well above a 3:1 ratio.

I've also used this antenna on several UHF Visars as well as other 'ham' rigs with a BNC/SMA adaptor, and I have NEVER burned a PA yet, and I get long winded to drop any timed repeater I use, so it has to be a good antenna, or I would have seen the ill effects long ago.

The HT1000 I sold is still using this very antenna back in WI. on the local machines near Wausau.

I grab as many of these antennas as I can, check them yourself, they will and DO work very well on UHF, and are fairly wide banded as well.

But NEVER transmit into one of those elevated feed dipoles, the radiating element is only 3" in length, and will cause PA damage.

There is a brass coaxial sleeve in those antennas, which decouples the the feed line from the lower radiating element, the radiating antenna feeds from the open center of this decoupler, and is supported by a rubber base with a clear teflon-type insulating material inside the decoupling sleeve.

Both the center pin and threaded stud are at RF potential with this design, with the threaded stud being the ground return path if you will.

You should also notice a degraded reception at UHF while using this antenna, but never transmit with it.

You can feel the decoupling element inside the plastic sheath if you lightly compress it or even gently bend it, it's just over 3" in length itself.


Okay, enough is enough, you know very well not to use that antenna to transmit with, no more said on that dead horse issue.


Enterprize.....One to beam up!