T-MAG ANTENNA 40-10m.

September 11, 2014, 1:49 am

≪ Previous: Single knop Travelloop 6.5 - 31 MHz

Concept for a small multiband antenna . Can be tuned with most internal tuners.

The unun is placed right in the midle of the 13m wire. This isn't a wonder antenna but it can provide good signals at a limited space on a field day or emergency . A V-configuration is also possible. Don't forget a line choke near the transceiver.

EASY SETUP

LINE CHOKE. 15 TURNS RG-58 ON A FERRITE ROD.

↧

Magnetic loop controller

October 9, 2014, 12:24 pm

≫ Next: MERRY CHRISTMAS

≪ Previous: T-MAG ANTENNA 40-10m.

There are several ways to control a magn. loop. The simplest direct coax fed method needs a second power source to avoid short circuit. A portable setup is better off with only 1 battery.
Here is a no thrills controler idea for qrp up to 100 Watt power levells. The motor is reversed if the zener diode recieves more than 9v from the 3 position swich. At 6v the relay is not activated so the motor runs forward. The chokes and diodes should be able to pass at least 1Amp. Chokes have 16 turns 0.8 mm transformer wire on a FT50-43 toroid. This controller is designed for 360 degree tuning capacitors . 180 degree tuning capacitors need protection by means of 2 miro switches and reversing diodes between the relay and the moter.
By adding high voltage capacitors ( silver mica ) for C1 and C5 this cotroller will handle 100 Watts.
The relay is activated by means of an over voltage protection circuit . To avoid RFI a small metal box is used for both units.

↧

MERRY CHRISTMAS

December 10, 2014, 12:26 pm

≫ Next: ZS6BKW galvanic feedline isolation

≪ Previous: Magnetic loop controller

↧

ZS6BKW galvanic feedline isolation

January 25, 2015, 7:12 am

≫ Next: 1:4 Voltage balun 3.5 - 30 MHz

≪ Previous: MERRY CHRISTMAS

Connecting a balanced antenna like a ZS6BKW to a coax feedline can cause serious problems be means of a high noise levell, for the cabinet of the transceiver is connected to the antenna. This means that all nearby QRM is transported to the trx by the coax schield. A galvanic isolator helps reducing this noise. 11 turns of side by side 1.2 mm magnet wire on a FT140-61 or 4C65 toroid formes the coupler. The coupler is placed at the low-Z feedpoint in the balanced feedline of the antenna. SWR is 1:1.3 at 3 MHz and 1:2 at 30 MHz. A additional line choke is a good option.
I used the 4C65 toroid for it was in stock but a FT140-43 with aprox. 8-10 turns might even be a better choise.

↧

1:4 Voltage balun 3.5 - 30 MHz

February 11, 2015, 3:22 am

≫ Next: Stubloop antenna

≪ Previous: ZS6BKW galvanic feedline isolation

Flat SWR from 3.5 to 30 MHz with 8 double turns on a 4C65 or FT140-61 toroid.
SWR 1: 1.1 in the centre.

↧

Stubloop antenna

April 3, 2015, 11:30 am

≫ Next: FT-817 / FT-857 / FT-897 speaker mod.

≪ Previous: 1:4 Voltage balun 3.5 - 30 MHz

The coaxial stubloop antenna is a 0 gain easy to build antenna for HF - VHF . It's a wideband sulution for emergency use or just as a back-up device. I pubished this article before but received mails for more info
.

PLASTIC STUBLOOP JUNCTION BOX

↧

FT-817 / FT-857 / FT-897 speaker mod.

June 10, 2015, 2:48 am

≫ Next: Wall Loop 20m.

≪ Previous: Stubloop antenna

The original speaker with paper cone is wel known for his high levell of distortion and noise.
A German model train distributor deliveres a 2 Watt speaker with a Mylar cone having the same size as the original. Replacing the speaker results in a much cleaner and louder audio without distortion. Your ears wil be pleased HI.

↧

Wall Loop 20m.

February 14, 2016, 3:01 am

≫ Next: DIY kits 70W SSB linear HF Power Amplifier For YAESU FT-817 KX3

≪ Previous: FT-817 / FT-857 / FT-897 speaker mod.

This max. size magnetic loop antenna for 14 MHz with a totall circumference of 6m. ( 19.68 feet ) is designed to attach to a wall . Not sutable for reenforced concrete walls . It has a no tune bandwidth of more than 300 KC with a centre swr of 1 : 1.1 The 150 pF parallel capacitor was the best value in my situation ( brick wall ) but can be replaced by a 250 pF tuning capacitor in order to find the lowest SWR at resonance. First contacts gave good reports in Europe. For max. performance be sure that the 'hot' side of the antenna points to the window. A test was made with 100 Watts without arcing however 5 Watts are more than enough for indoor use...
The top capacitor is made of twisted antenna wire or a piece of 25cm RG-213 coax and is cut for tuning to the frequency . This antenna can also be build on a fibre frame for field or attic use

The capacitor . A piece of RG-213 coax can also be used

Verry good SWR

Feedpoint with 100pF and 47pF in parallel. Notice the line choke.

↧

DIY kits 70W SSB linear HF Power Amplifier For YAESU FT-817 KX3

November 12, 2016, 5:39 am

≫ Next: Article 0

≪ Previous: Wall Loop 20m.

It's time for a new project. eBay link to the seller

OM's in need of a doc. copy please send me a mail , i'm happy to help. E-mail adress at QRZ.com
It seems that the seller often forgets to add the doc. ....
My first impression : High quality PCB , all parts in the kit including 2 power FET's type IRF530N.
However i had doubts about the claimed 70 Watts output at 13.8V for these fets are normally fed with 24 - 36V to get a good modulation.

The first test was in the original configuration at 13.8V and 5Watt input from my FT-817. Max. power 80 Watt but the input swr on tx was 1:2.2 much to high. At 4 Watt input the swr drops to 1:1.5
Output was about 65W at 20m.but the modulation was as expected distorded at 2.7V bias voltage.
At 3.7V bias the modulation is verry acceptable.
5 Watt transceivers need a 1 dB attenuator to work with this Amplifier.

↧

Article 0

December 6, 2016, 1:43 pm

≫ Next: EFHW antenna for 40-10m qrp

≪ Previous: DIY kits 70W SSB linear HF Power Amplifier For YAESU FT-817 KX3

↧

EFHW antenna for 40-10m qrp

January 20, 2017, 6:25 am

≫ Next: Coax to a pcb

≪ Previous: Article 0

A small QRP EFHW transformer is possible using a BN43-2402 balun core from 7 - 29 MHz. As you can see in the plot the swr is verry flat from 40-10m so a capacitor at the input is not needed. A 3300 Ohm resister to the ground was usesed for the plot. With just 20.3m wire this makes a nice 40-10m antenna. You can also use the 34uH coil of the endfed down this blog to create a compact 3 band atenna of just 12m long. I think 20 Watts PEP is the max. power here. Be carefull, each pass is 1 turn here.

↧

Coax to a pcb

March 24, 2017, 7:40 am

≫ Next: Coax to pcb the easy way

≪ Previous: EFHW antenna for 40-10m qrp

Soldering a coax in to small pcb holes can be verry stessfull. Teflon coax is the best choise.
Here is the solution:

↧

Coax to pcb the easy way

March 28, 2017, 12:18 am

≫ Next: Voice keyer ( CQ parrot )

≪ Previous: Coax to a pcb

Soldering a coax braid in to small pcb holes can be verry stessfull. Teflon coax is the best choise.
Here is the solution

↧

Voice keyer ( CQ parrot )

April 2, 2017, 8:17 am

≫ Next: Half wave sota antenna idea for 20-17/15/12-10m.

≪ Previous: Coax to pcb the easy way

Calling cq in ssb with ony 5 Watt can cause a sore throat....
Although in production for severall yaers this exellent kit BX-184 from Box 73 is stil a must have for the QRP operator. Link
Easy to build high quality kit that provides 60 seconds voice recording and a strong punch to the modulation . I had to reduce the mic. gain to 25% on ssb and 15 % on fm/am at the FT-817.
This kit is also available with a extra MH-31 type mic. enabeling the use at other transceivers with 5V or more at the mic. cable. The red dot marks the fst button that controlles the functions,


The modified MH-31 mic.with pcb

↧

Half wave sota antenna idea for 20-17/15/12-10m.

June 26, 2017, 2:01 am

≫ Next: IC-7300 preselector idea.

≪ Previous: Voice keyer ( CQ parrot )

The famous endfed with wireman 450 Ohm can serve as a short 3 band antenna . The short part of the wireman can be calculated for 17-15 or 12m. No coil or trap needed.

↧

IC-7300 preselector idea.

July 17, 2017, 5:55 am

≫ Next: Antenna switch .

≪ Previous: Half wave sota antenna idea for 20-17/15/12-10m.

The IC-7300 has a signal overload problem. A preselector can salve this problem.
L1 - T80-2 . L2 - T68-6 . L3 - T50-6 .

↧

Antenna switch .

July 29, 2017, 10:00 am

≫ Next: QRP labs QCX 5 Watt cw trx kit

≪ Previous: IC-7300 preselector idea.

By means of a 230V switch a reliable 100 Watt antenna switch can be made with
2 advantages.
1: the switch points to the connected antenna.
2: the non connected antenna is grounded.
The picture shows the switch from behind.
I used a 15A switch

↧

QRP labs QCX 5 Watt cw trx kit

August 25, 2017, 2:03 am

≫ Next: Merry Xmas

≪ Previous: Antenna switch .

Here is my new winter project: http://qrp-labs.com/qcx.html
I couldn't resist buying this little 10 x 8 cm gem with a lot of features for just 49$
The two SMD ICs are already factory pre-soldered.
A nice enclosure for this transceiver can be found on eBay : Link

More info coming soon.

↧

Merry Xmas

December 20, 2017, 12:50 am

≫ Next: Yaesu VX-3 double battery idea

≪ Previous: QRP labs QCX 5 Watt cw trx kit

↧

Yaesu VX-3 double battery idea

April 24, 2018, 5:54 am

≪ Previous: Merry Xmas

A small radio has a small battery so i came up with this idea. A battery case for AA size batteries is available on the net . By removing all inside material with a Dremel tool enough space is created to hold 2 Li-ion batteries in parallel. Two thin brass strips can be used to solder the packs together resulting in a 2800 mA powerpack. Look for Fuji NP60 batteies on ebay , they are simply glued together .Some foam rubber is needed to fill up the extra space between the pack and the cover.
Those who don't like to solder a battery can glue the 2 cells in anti parallel. You need to flip the pack if one cell is emty.

Before soldering

Flip pack

↧