Building a 1/1 Current (Choke) Balun

Another simple useful device: 1:1 current balun, used as a choke for RF suppression. I've built this balun following this site: http://kambing.ui.ac.id/onnopurbo/orari-diklat/teknik/balun/current%20balun,%20current%20choke,%20choke%20balun,%2050%20ohm%2011.htm

The core is an FT140-43 toroid and the winding is made of RG-174 coax cable. On antenna side I added a 10kohm - 1W resistor in parallel between cold and hot connector of the PL for static suppresion. The final result is here:

SWR with 50 ohm dummy load is 1:1 160-10 meters, on 6 meters SWR is better than 1.5:1. At this time I've not tested the balun on the air.

Building a 4/1 Current (Guanella) Balun

I need a 4/1 balun for feeding balanced antennas, such as Up-and-Outer (my preferred antenna) or M3KXZ 'no counterpoise' antenna.

I've built one following the instruction found on this link: http://www.n0ss.net/qrp_4-1_guanella-type_balun.pdf

I use a single core, FT140-43 toroid, enclosed in a little black box, using two "banana" binding posts for wire and panel female BNC for feeding.

The result:

Another photo: Box closed and added 32mm diam. clip for fishing pole locking

Very simple to build! Results: VERY VERY VERY good! I.E. North Patagonia on 15m with 2.5 W using up-and-outer antenna! See http://iz8jji.blogspot.it/2012/07/a-great-qso-un-15m-with-lu.html

I've not used this device on 80 or 160 meters but the performance expected is not so good. I've tested the balun in 6m but the performance are very poor!

Building a 9:1 Un-Un for longwire antenna

I'm always fascinated by the "magic" 9/1 un-un for longwire antennas, also called "Magnetic Longwire Balun". You build this device, connect the transceiver and a longwire antenna of almost random wire, and GO!!! No SWR on 160/10 meters, no Tuners, perfect.....OR NOT?

The background study:
If you google "Magnetic Longwire Balun" you may find a lot of experiences of many ham operators all around the world about this antenna. The cores used for Un-Un are various: ferrite sticks, FT and T Amidon toroids and even cores from old TV EAT transformers.

There is also a SWR table versus wire lenght, found somewhere in the 'net attached to manuals of commercial longwire antennas (click image to enlarge):

I suggest to look at M0UKD web site for a quick guide to build a 9/1, If you want to deep in with different cores and expected performance, read:

• G3TXQ web site contains a very good article (http://www.karinya.net/g3txq/unun/) on cores and ratio comparison for 9/1 and 4/1 un-un.

•  G8JNJ web site has a very good article (http://g8jnj.webs.com/cometcha250b.htm) on building a clone of the Diamond BB6W wideband antenna (scroll down...). The balun used is a 6/1 but there are some interesting facts and tests on various cores.

Building the 9/1 Un-Un 
My requirements was:

• 80m to 6m use
• QRP or max 100W power
• light and little for portable use

I use an Amidon toroid, a T130-6 with 9 turns trifilar using insulated stranded wire. For the box, I choose a grey PVC coupler (40 cm diam.)  and two caps. Connectors are PL female for TX and M5 screw for antenna wire.

The Un-Un have no hooks for hanging, but I arrange also two insulators made of hard white plastic (teflon?) from a chinese chopping board. The right one is for connection to Un-Un (using the third hole for hanging) and the left one is for wire end.

The SWR of Un-Un with a 470 ohm dummy load was measured and better than 1.3:1 from 3.5 to 50 MHz..
I've made several 9/1 for me and for some friends using different materials. On-air performance is sufficient, not bad for a so simple antenna.

Cores used in the Un-Un :

• Amidon toroid (T200-2, T130-6, FT140-43, FT240-43)
• Unknown Yellow-and-White toroids (I suppose are for switching power supply)
• Ferrite sticks from old AM radios

In order to chioose the core material, mind this simple facts:

• Using Amidon cores (in particular TXXX-2 and -6) the losses are relatively low and the performance of the antenna is better, but in the lower bands you may need a antenna tuner to obtain good SWR. Otherwise, if you don't like to bring ATU, try to use a "long" coax feeder (more than 10 meters)
• Using low frequency toroids or ferrite sticks the losses incrase a lot, but this lower your SWR and you don't need an ATU at all.

Another 9/1 Un-Un I made for a friend with ferrite stick

UPDATE!
Look my new "Shorted" longwire antenna

Mayor update to the shack!

In the last three months some new radios comes to the shack! Let me present the new entries:

• ICOM IC-7200

This is really a G-R-E-A-T Radio!!

- HF and 6m SSB-CW-RTTY-AM (no FM at all, no chat in 10 and 6m, too serious radio for this)
- 100 W power out (no problem for QRP: power may go don to 2 Watts)
- Rugged style, heavy weight, splashproof, looks similar to military manpacks
- Digital IF DSP, 3 different user selectable settings
- Manual and auto Notch filter
- Direct connection to PC USB port!!! (no need for CI-V, modems, cables and other junk)
- Simple to use, no bells-and-whistles
- Simple settings

Fantastic, for me is Nr. 1!

• Polmar Wild

In my neighbor 2 meters FM activity seems to awake again  after a while. I spend many hours of the day in my car because my job is far from home (sigh....), and I've bought a vehicular VHF radio.
This radio is identical to TYT TH-9000, Polmar is an Italian brand who sells this radio with two-years warranty and local servicing, at a price almost identical to the "original" chinese sellers (if you don't believe, look at ebay and see!)

Pros:
- Small and light, big heater sink
- Cheap and simple to use
- 60 W power out in 136-174 coverage
- Usable as ham operator and LMR (CTCSS, DCS, 2 tones, 5 tones, password to protexct settings, etc.)
- Compander! (really, this radio have a compander, I'don't believe it)
- Fully PC programmable with an optional USB cable
- DTMF and multi-function microphone (looks very smart)

Cons:
- Compander: sure, the compander is great in TX and for weak signals, but in regular traffic with your neighbors running 50 watts and 0,5 km of QRB....Is not possible via menu and prog to activate the compander in TX only, I'll search a mod....
- Manual: NO COMMENT!, very few functions are documented....I agree that the radio is simple and may be used without manual, but .....anyway, you MUST download the TYT manual and software for programming this rig, see the this page on the 'net: http://tinymicros.com/wiki/TYT_TH-9000 for donloading.


Despite to the manual, this is a very good radio for the buck!

•  Autophon Radiovox SE-155 (Ascom SE-155)

OK, after a dream radio, let's go to some different job: I've found on the Bay a very cheap surplus. I've bought for fun mods on 2 meters band. Stay tuned for following chapters

Alternative microphone for Yaesu FT-817

Since I'm using the 817 mainly in /P, the original mike supplied with the radio is very stressed for the job. I've found an alternative one wich seems very useful for me: Vertex MH-67A8J. This mike is pin-compatible with MH-31 and is factory-supplied with Yaesu Ft-450 and also with some Yaesu/Vertex Land Mobile Radios (like VX-2100).

Is very big (almost twice that MH-31) and looks very rugged.

I've got one for few euros for an Italian ham and I've done a few on-air test on last sunday, and other hams reports that sounds identcal to MH-31.

TS-50 to LDG Z-100 plus connecting cable

Using the infos gathered on the net and showed in my previous post, I'm ready to build a quick-and-dirty cable.

Purpose of the cable:
- DC supply the LDG tuner from TS-50 ACC connector
- enabling the "AT TUNE" button on TS-50

The sketch below shows the circuit (press to enlarge). The ACC conncetor is shown radio side.

The TT and TS lines are connected together via a 3.3 Kohm resistor. The + and - lines are connected to LDG power conenctor via a 1 A fuse on the NEGATIVE path of supply lines.The ACC connector used is a PC surplus connector as shown elsewhere in my blog.

The final result is in the photo below:

Ok, seems like a sort of wire patchwork (green, white, black, red, yallow....) but IT WORKS!

Using the tuner with this cable is simple:

- Press TUNE button on LDG
- Press AT TUNE button on TS-50
- Wait for a match
- REMEMBER to shutdown the carrier pressing again AT TUNE on TS-50

Interfacing Kenwood rigs to LDG Tuners

 

I need to connect my LDG Z-100 plus tuner to my Kenwood TS-50, and googling on the net I've found some useful information in order to understand the Kenwood tuner interface. I'll show the much interesting things I've found, may be useful tu someone. (some of the documents linked are in Italian)

Technical Description of the Kenwood Tuner Interface:
http://www.ham-kits.com/KWTuner/KWT%20technical%20description.pdf

Other interesting things:
http://home.ix.netcom.com/~hmlong/

http://www.arimagenta.it/progetti/pdf_doc/ICOM%20TUNER%20+%20RADIO%20KENWOOD.pdf

http://www.kb2ljj.com/data/kenwood/ts-50.htm (scroll down)