|9:1 Wideband RF Transformer Kit
For SWL Receiving
- Smooths the extreme impedance swings associated with end-fed antennas as they pass
through odd and even, multiple or sub-multiple, resonant points.
- Allows maximum signal energy transfer from antenna to 50 - 75 ohm feedline.
- Provides a continuous bleed of static electricity by DC shunting the antenna feed to ground.
- Rejects common-mode noise signals that are present on the coaxial shield, and keeps them
from entering the antenna feed line.
- Offers additional protection for sensitive solid state equipment from nearby lighting strikes,
by offering a high impedance to the high frequency components of the strike and DC
decoupling of induced voltages to the antenna feed line. (Note that due to the unpredictable nature of lightning
and nearby strikes, no guarantees or performance claims for the transformer can be made. A direct lightning strike will likely destroy
this transformer, the antenna itself, and any/all equipment connected to the system.)
|30KHz to 30+MHz (Flat from 300KHz 30MHz)
End-fed Antenna Transformer Kit
* * * PRELIMINARY RELEASE NOTICE * * *
This transformer is built on a design that has been developed and refined from several years
of R&D, prototyping, and beta testing, to determine the best combination of transformer core
material (ferrite mix), winding configuration, inter-winding coupling, source impedance,
terminal impedance, and efficiency.
The basic design considerations for this model transformer are to provide:
1. A very flat transformation response from 300 KHz to 30+ MHz, and down to 30KHz with a
3-4dB loss, which includes the LF (lofer and NDB-nondirectional beacon band), MF (AM
broadcast band), and HF (shortwave band).
2. A significant smoothing of impedance swings at non-resonant frequencies to more closely
match a 50 - 75 ohm load (or source) and provide maximum signal energy transfer.
3. A total broadband loss of less-than 0.25 dB (3-4dB loss at LF frequencies).
4. Absolutely minimal inter-winding capacitance.
5. Over-designed, heavy construction for long life and reliable weatherproof service.
6. Completely weather and environment proof against UV, ozone, moisture, salt, environmental
alkali and acids. Assembled with non-corrosive, non-rusting hardware and marine epoxy
7. Common mode choke against RFI (electrostatic and electrodynamic), local pickup (acting as
an antenna to strong local signals), and neighborhood / household noise sources.
8. Isolation / shunt of DC static buildup currents.
Heavy, gold plated, 5-way binding posts for the antenna and ground connections.
Non-rusting, corrosion resistant, plated SO-239 coax connector.
Environmental resistance to corrosive and caustic elements, plus salt, ozone, and UV
Direct ground connection included (the correct way) at the feed point (recommended and
available, but not required for operation).
|A photo of a typical kit of parts and wiring instructions.
You just supply the enclosure..
We request that you contact me (below) to indicate your interest in this product.
You are not obligated, in any way, to purchase this product, but your interest to purchase one is
important to our planning and scheduling.
We will not accept any funds until the product is available for immediate shipping.
I usually ship within 3-10 business days of payment via PayPal.
Payments received via check through the postal service will be held for check clearance - usually 10
A note on the cost of this item:
The cost of the parts for these transformers have not been spared; they represent the bulk of the sales
price. The components are of the highest quality available. Very little allowance has been given for labor
costs (mine), and any funds above and beyond the cost of parts will go toward maintaining this Web site.
Please send your intentions to buy, or interest in, the these Antenna Transformers
to me. You are not obligated to purchase this item in any way - click here.
Once sold, only the owner of the transformer is responsible for its safe and proper installation and use. The maker or seller
assumes no responsibility for proper and safe installation and use. Damage, of any kind, including storm, lightning, and any other
hazards of Nature or accident, whether intentional or coincidental, are the sole liability and responsibility of the owner
No refunds, returns, or replacements will be honored unless the item fails to function as specified. The seller is not responsible for
lack of technical knowledge in installing or use of the item, damage incurred, or any other personal, material, or monetary liability.
The customer is expected to ask questions of the maker if in doubt as to proper installation and/or safe use, and to read and retain
any/all instruction materials.
Returns must be in "as received", re-saleable, factory fresh condition and accompanied by all original paperwork, packing,
Shipping damage must be claimed by the buyer and filed with the delivery carrier upon receipt of the item. The shipper assumes no
liability for shipping damage or any other damage beyond his control.
T-5030 $45.00, (Plus $5.00 shipping, USA)*
30KHz - 30+MHz.
Lowfer, Medium Wave (AM broadcast band), Shortwave band, 50 KHz through 30 MHz (LF, MF
& HF), 9:1 impedance ratio.
|IMPORTANT NOTE: As of July 1, 2010, I am suspending the manufacture of these transformers. In order to restock inventory, (we sold all the transformers built from the
original parts purchase) I have been searching all available sources for the materials required, and find that, almost without exception, all prices have increased - in some cases, not
just a little increase! This is so much so that I cannot hold the original price any more. The original price of $45.00 USD included $34.00 worth of component costs. All first rate
components, the Teflon (R) SO-239 connector, gold binding posts, stainless steel hardware, epoxy potting compound, and ferrite cores have all risen in cost, dramatically! The total
increases would bring the cost of materials up to (almost) the selling price, leaving no margin for time and labor. Even the shipping costs have increases
Granted, I could use lesser-quality parts and lower the manufacturing costs, but as with everything I have offered so far, I try to design to (or close to) MIL-SPEC assembly and
component standards, for quality of performance and operational durability. This design is exceptional and meets the qualifications that I would want for my personal use. In fact, the
very first unit is still in use, feeding a Marconi antenna to my listening post. The same design is used in the RFP-1, with multiple taps to offer 36, 50, 75, 150, 300, 450, 600, and 1200
Ohms. The design criteria was simple: minimal loss, wide bandwidth, and high saturation level. If I cannot get back into the business of building baluns, for practical and
economic reasons, I will make this proprietary design available to the public.
I wish to thank all of my previous customers for their nice comments and feedback; it's appreciated.
If you really, really need a 9:1 module, or a kit of parts (as shown), you are invited to e-mail me and we can discuss the current economics (to which we have all fallen
victim), and I'll be glad to offer a quote, but please don't blame me for the current sagging dollar and inflated costs. Yes, I'm angry, if not just very disappointed, and I count myself
along with so many other small businesses - unfortunately, these devices don't fall under any Stimulus Program.
Thank you for understanding.