On 7 abr, 14:24, "Geoffrey S. Mendelson"
wrote:
Wimpie wrote:
Universal Radio mentions USD 66.95 for the antenna. It is probably
worth the price, but it doesn't mean it is better then a home brew
construction or give better reception with respect to your current
setup.

As I said before, a friend of mine has their ham version, which is what I
base the following comment on. The quality of construction and materials
used is very high. It is not an antenna that your average guy is going to
duplicate for a lot less money.

Assuming I could figure out the wiring for the loading coil and the traps
(his has traps, I don't know if this one does), I could duplicate it,
but it would look like something someone with knowledge, but little skill
had built (becuase it would be built that way).

If I were in the US, I would buy one. Since ordering things like this is
difficult, and delivery services cost a small fortune (an order sent via
UPS or FEDEX would cost at least $50 and probably $20 in taxes), I would make
one an live with what I had. :-)

The transformer/common mode choke has same functionality as the PAR
antenna. In addition I can disable the 1:9 impedance transformer
(while the common mode filter remains). I use a narrow band tunable
preselector to avoid "noise" from intermodulation products.

Can you describe it better? a 1:9 balun as it were is easy to make, and 1:4
VHF TV/FM radio ones are getting harder to find, but are still out there.

Thanks, and 73,

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel *N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.

Wimpie wrote:


As far as I know the proposed antenna is a single wire (without traps)
in combination with a 1:9 impedance transformer. www.parelectronics.com/swl-end.php
shows some details. It uses a two-hole ferrite core and is for receive
only. You can disconnect the antenna side ground from the 50/75 Ohms
cable braid to optimize for minimum noise.

The one I made myself is an autotransformer with a separate common
mode choke. The autotransformer enables me to extend the useful
bandwidth downward without getting too much leakage inductance.

As my transformer has no galvanic isolation, I needed a separate
common mode choke. The common mode choke is a series circuit of 2
wound ferrite cores. The first core with RG174 has best performance at
the middle and upper part of HF. The second core with RG174 coaxial
cable has its highest common mode impedance around 3 MHz.

If you need further clarification, don't hesitate to contact me.

Best regards,

Wim
PA3DJS
www.tetech.nl
remove abc first before hitting the send button.

http://www.bobsamerica.com/9-1balun.html

On Apr 7, 7:45*am, dave wrote:
Wimpie wrote:

As far as I know the proposed antenna is a single wire (without traps)
in combination with a 1:9 impedance transformer. *www.parelectronics.com/swl-end.php
shows some details. It uses a two-hole ferrite core and is for receive
only. You can disconnect the antenna side ground from the 50/75 Ohms
cable braid to optimize for minimum noise.

The one I made myself is an autotransformer with a separate common
mode choke. * The autotransformer enables me to extend the useful
bandwidth downward without getting too much leakage inductance.

As my transformer has no galvanic isolation, I needed a separate
common mode choke. The common mode choke is a series circuit of 2
wound ferrite cores. The first core with RG174 has best performance at
the middle and upper part of HF. The second core with RG174 coaxial
cable has its highest common mode impedance around 3 MHz.

If you need further clarification, don't hesitate to contact me.

Best regards,

Wim
PA3DJS
www.tetech.nl
remove abc first before hitting the send button.

http://www.bobsamerica.com/9-1balun.html- Hide quoted text -

- Show quoted text -

This looks like a basic good design, but it is different from PAR's.

Bruce

dave wrote:


http://www.bobsamerica.com/9-1balun.html

Interesting - Bob is a local friend - didn't realize he had that up on
his website.

He's got a wealth of information on his web site for people who enjoy
building accessories.