[Antennas] B&W AC 1.8-30 vs BWD terminated antennas?

Mon Sep 6 15:22:07 EDT 2004

Ahh there WAS a "magic" antenna matching device that was marketed back
in the 80s that did exactly that! KE5O and myself looked at one (at the
same time we looked at the B&W BWD antenna which our company had one up
for use on ALE radios on HF Power Freqs..)..the "secret"???(which was
also exposed in QST later on) was a 50ohm 100watt resistor!!! Talk about
a rip off..You want LOW SWR AND max radiation? Get a tuner and a ladder
line fed dipole cut for the lowest band (even one fed with coax would be
better than that device :)....You want lowest swr? Hang a dummy load at
the end of coax..with NO wires...see how many contacts you make (yes it
is possible...but HIGHLY unlikely 99% of the time; KE5O did just that as
a Novice in 1972...made a crosstown contact on a Heath DL...... :)
ANY SHORT (in terms of wavelength) antenna that has a RESISTOR is using
the resistor to absorb RF and minimize SWR..
A LONG wavelength antenna like the rhombics, etc do not use the resistor
to absorb major RF power level (which is why you can get away with a 2
or 10watt resistor at the end of such...the B&W uses a 100-150 watt
resistor!!!...HMMMM yet the antenna is only rated for that much power at
its feedpoint...though it has a 16:1 balun which looks like it could
handle 150+ with no problem---the B&W is a compromise...and a poor one
at that)
BTW concering a post on ALE HF radios, the Harris HF radios my former
company (Entergy/Gulf States Util) uses with its ALE system also uses
the SGC auto tuners with 25ft fiberglass verticals at some
locations....switched just fine; there are units out there that work
with ALE and much better!....the B&W at our main office which was tilted
(and tilting does NOT impove any operation; Dr John Kraus, W8JK, proved
that years ago on this exact antenna!) was eventually replaced by 30ft
of Rohn 25G used as a vertical...with 16 radials under it and a SGC
tuner on it..the signals were much stronger (10-15db) on this setup than
the B&W anyday..
Chris
WB5ITT
> -----Original Message-----
> From: antennas-bounces at mailman.qth.net 
> [mailto:antennas-bounces at mailman.qth.net] On Behalf Of Buck
> Sent: Sunday, September 05, 2004 10:58 PM
> To: antennas at mailman.qth.net
> Subject: RE: [Antennas] B&W AC 1.8-30 vs BWD terminated antennas?
>>> BTW, that works! I once had a 100 ohm/300 watt resister. 
> For kicks and giggles, I cut wires for an 80 meter dipole, 
> connected them to either end of the resister like a cobra 
> head and ran coax to the wires. The resistor was actually 
> between the shield and center conductor with the wires 
> extending outwards. The antenna worked on 80-10. When I 
> checked into the 75 meter net, I did not have a great signal, 
> but I was readable. Ten meters was open and I made several 
> contacts, but when I removed the resistor, the receive signal 
> improved incredibly! The SWR was under 3:1, but I don't know 
> by how much. I had a tube rig and that was all I worried 
> about. Today, we want 1.5:1 or better. 
>> BTW, I DON'T recommend that for a QRP antenna unless it is an 
> emergency. Then a dipole would be better.
>> FWIW.
>> Buck
> N4PGW
>>>>> -----Original Message-----
> From: William Lambing [mailto:w0lpq9 at msn.com] 
> <<<SNIP>>>
>> Having a resistor at the feed point is about like putting a 
> dummy load at the end of the feed line and hanging wires out 
> to radiate.
>>>>> - - - 
>> Your moderator for this list is:
> Larry Wilson KE1HZ antennas-owner at mailman.qth.net 
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