Topband: Beverage transformer questions

[Mike Waters W0BTU]

--- On Thu, 3/4/10, Joel Harrison <w5zn at w5zn.org> wrote:

> From: Joel Harrison <w5zn at w5zn.org>
> Subject: RE: Topband: Newbie report
> To: "'Mike Waters W0BTU'" <mrscience65704 at yahoo.com>
> Date: Thursday, March 4, 2010, 10:42 AM
> Hi Mike,
> 
> The photos look very nice. What cores are you using for
> your transformers?
> 
> 73 Joel W5ZN

Hello Joel,

I get asked that and related questions quite a bit, so I'm cc'ing this to the Topband list. Glad to help, and thanks for asking.

Below is a copy of a reply to someone else. Let me know if you need more info.



The transformers in the photos are made from FB-73-801 ferrite beads. Two pairs of four stacked. It's what I had on hand.

If you're going to buy ferrite, get those binocular cores from Amidon (73 material) instead, as it will save you a lot of work gluing and heat-shrinking the beads together. I forget the part #, I can look it up if you want (starts with BN). I bought some in my last order from Amidon, but haven't tried them yet.


> Also, what is the value of the rf choke on the
> bias tee in the remote unit?

I don't know what the value is. It's a single FB73-801 ferrite bead with some #24 (I think) enameled wire wound through it a few times. The wire size and # of turns is not critical. I think the DC blocking capacitor is a .01 uf 100 volt disc ceramic. [There's a similar choke at the station control]

I always took care not to skin the enamel off the wire when pulling it through the beads (they're conductive). I have a tiny file I take the sharp edge off the hole with.

The components across the [12 VDC] relay coil: a 30 volt MOV and a .01 or .1 uf disc ceramic.


> What is the length of the radials on the far
> ends?
> Both of my beverages work OK in the forward
> direction but don't seem to have much front to back.
> Neither has the gain or S/N of the forward direction.

That's the problem I had when I first installed these Beverages. The problem was an insufficient ground.

> I have
> been thinking about adding radials to the far ends but I
> don't know what lengths to make them.
> Any suggestions?
> Thanks,


The radials are 50 or 60 feet long. The Beverage with the 7 radials: one or two of those radials are maybe 40 feet. You need a better ground at the far end, along with a ground rod (two are better) to provide a decent return to ground for the reflection transformer. Otherwise, you won't hear as well off the back end (at least in my soil here). I only use three radials at the feed end (with two rods).

Let me know how else we can help.

73 Mike




> 
> 
> -----Original Message-----
> From: topband-bounces at contesting.com
> [mailto:topband-bounces at contesting.com]
> On Behalf Of Mike Waters W0BTU
> Sent: Monday, March 01, 2010 11:44 PM
> To: Mark Lunday
> Cc: topband at contesting.com
> Subject: Re: Topband: Newbie report
> 
> Hi Mark,
> 
> I would be very happy to provide details of my Beverage
> receiving antennas.
> 
> I cc'ed this to the Topband list. There are a lot of good
> people there who also have Beverages, that can help you.
> 
> 
> You will hear lots more on a Beverage than on an
> inverted-L, or even a 1/4
> wave vertical. But Beverages require some room. Mine are
> 580' long. (How big
> is your property?) You can see some photos at
> http://picasaweb.google.com/katie65752/BeverageAntennas#
> The photos at the beginning were to demonstrate how
> incredibly strong the
> plated steel electric fence wire was. 
> 
> I plan to put up more info on a web site, when I get the
> time and energy. In
> the meantime, if you have the book "Low Band DXing", by
> John Devoldere ON4UN
> (4th edition), he describes the Beverage. I'm not alone
> when I say that I
> highly recommend his book.
> 
> In addition to 160, I also enjoy SWL DX'ing on the AM
> broadcast band. On
> some frequencies, I can pick out four different stations
> simply by selecting
> a different compass direction.
> 
> If you don't have a lot of room for Beverages, there's
> alternatives, such as
> the K9AY Loop.
> 
> I suggest you do also a Google search for "Beverage
> antenna" (with the quote
> marks) if you want to read more about them. Another good
> search would be to
> search the Topband archives for the same thing.
> 
> They are incredible antennas. You can't transmit on them,
> but do they ever
> pull weak signals out of the noise!
> 
> 

> 
> 73,
> Mike Waters
> W0BTU
> 
> 
> --- On Sun, 2/28/10, Mark Lunday <mlunday at nc.rr.com>
> wrote:
> 
> > From: Mark Lunday <mlunday at nc.rr.com>
> > Subject: RE: Topband: Newbie report
> > To: "'Mike Waters W0BTU'" <mrscience65704 at yahoo.com>
> > Date: Sunday, February 28, 2010, 4:53 PM
> > Thanks, Mike!
> > 
> > Can you plz send more info on your beverage, and can
> we
> > discuss some
> > details?  Obviously the Inv L is not the best
> > receiving antenna.


73,
Mike Waters
W0BTU