SEM 52-S military handheld

Months ago, I've bought a german military handheld: a SEM 52-S. Specifications: see http://www.kpjung.de/e_sem52s.htm
Is an FM handheld with frequency coverage that includes 6 meters, 1 watt circa power out, very big and weighty, but so cool! 6 fixed channels programmable with internal contraves.




The radio is a SEM 52-S/FZ/46 and is not born as an handheld: is user on tanks with a mount, see http://www.greenradio.de/e_sem52sfz.htm, but is useable as handheld using a SEM 52-S battery pack (delivered with the transceiver).
I've also the antenna, a long (93 cm!!!) SEM 52A antenna, with fits perfectly in SEM 52S

• First Job: rebuid battery pack

The battery pack comes with a broken, unusable NiCd battery pack. The box is also very dirty and in bad conditions. I build a new battery pack using two docks for 4 AAA battery, and fit in 8x900 mAh NiMH AAA. The result is shown below:

• Second Job: arrange an alternative antenna

I have an original antenna, but is very long (93cm) and I want a smaller one for short-range contacts. I choose to modify a commercial item. I buoght an old 43 MHz whip antenna: 43 MHz is almost a dead band, and dealers are happy to sell one for a very discounted price. The antenna is a CTE model HP-FLEX/B.


The antenna is 54 cm long. Using the FT-817 as a tunig tool, I cut the antenna until a dip in SWR happens (I stop at 1.5:1). The antenna is now 36cm tall (from bottom of BNC connector to top of the whip. See the shorted antenna mounted on SEM 52-S


Next job: building a speaker-microphone (to do)

Yaesu SSB Filter XF-119SN for FT-817

I've bought an SSB filter for my FT-817. The filter is NO cheap at all, but I've found an used item for half price. Installing the filter is simple: open upper cover of FT-817, locate the two connectors on the low right side of the board and mount the filter.


The filter is enabled/disabled via main menu.
The results are very good: great improvement in RX, the selectivity is really much better. Suggestion for FT-817 owners that use mainly SSB: buy one, also on full price!

Simple window loop antenna

I've no way to set any antenna on the top of my building. This is the reason because I'm often in /P. But also at home I've some QSO using strange antennas. This is one of them: a window loop!

I've a window 158x140 cm pointing to east, with no other buildings in the way. A wire installed in the window perimeter is circa 1 wave lenght in 6 meters.


Anyway, the loop is not resonant on 6 meters: is not a perfect 1 lambda, the wire is too near to radiator etc., so I use this loop as an untuned loop, connecting a tuner in the low right corner of the window, as shown above:



Results: amazing! Hungary and Ukraine in 6m! I use this antenna also on 10, 12 with good results. On 15 meters the results are acceptable, but I've got very few QSO in 20 and 17 meters.

Next step: trasforming the untuned loop in a short magnetic loop for the 20 and 17 meters.

PL support for camera tripod

I've built a simple support for using HF and VHF mobile antenas with a camera tripod.

The base is made of plywood. The support for BNC connector and ground connection is a small steel "L" piece, wich may be found predrilled (fits also BNC!) in any hardware store.


The two wing nuts are for radials. Detail view:

12V 6800 mAh LiPo Battery

I've bought on e-bay a LIPO battery, 6800 mAh, from a Hong-Kong seller for few euros (a bit less than 35). After about three weeks, the battery arrives. Specifications:

• Weight 230g
• Measures: 56x106x18 mm
• Input (for charge) 12.6VDC
• Output: 12V 6800 mAh

The battery comes with a charger and have a little on-off switch and red led.


I've used often with FT-817 in /P, and also as a emergency supply source for handhelds. Great item!

Two stands for FT-817

The first stand is an homebrew item, built with a CD case following the instructions of KR1ST:

The second stand is a commecrial item (buuh!): IKEA sell this item as an alarm clock, is cheap (7 Euros), light, give a touch of design to setup and tells GMT time for free ;).The idea is not mine, I've seen a post from IW4BIC in an italian FT-817 fan forum.

K2S: An Yaesu FT-817 Knee Support

It's very fun to going around in /P with an FT-817, few meters of wire and a fishing pole! I often sit on a rock or on a little foldable chair and have many nice QSO with the little radio standing on my knee.

But in this way the DC connector is stressed, and obviously my DC conector was broken soon (the connector on the radio, soldered in SMD to main printed board.....sigh!!). Very disappointing indeed.

OK, let's resolve the problem: I've built K2S (KISS Knee Support), which is used to avoid stress to DC cable while the FT-817 stand on knee.

Is very ugly and simple, but it works! Ia a piece of plywood cutted to fit the two "wings" on the back right side of the radio. Near the end of plywood i glue a slice of cork wine bottle cap to support on the left side of radio, geting me able to use the rear PL connector,

This is K2S, with the measures...very ugly!


A more clear draw:

K2S in action!



Looking closer...

Tiger Tail published in SPRAT!

I've sent the notes to build a Tiger Tail, as shown in my previous post http://iz8jji.blogspot.com/2011/04/boost-your-ht-for-almost-nothing.html to Colin G3VTT, and he agree to publish the notes in his column AAA (Antenna Anectodes and Awards) of SPRAT, bulletin of G-QRP club.

The notes were published in the Autumn 2011 issue.

Racal ANT-129 tripod support

I've built a more stable support for my military antenna. The support is made with a almost square slice of steel tube, a gift from Mimmo IZ8SQL, which had also the main idea of the support (TNX Mimmo!). Other items may be easily found in any hardware shop.

Parts needed:

• nr. 1 slice of square steel tube, approx 5cmx5cmx5cm
• nr. 1 inox bolt M10x20 (10mm dia x 20 mm lenght)
• nr. 1 "big" 10mm nut (lenght approx 3 cm
• nr. 1 20mm electrician grey PVC coupler
• nr. 2 10mm washers
• nr. 1 banana female connector

Drill three holes in the square tube:

Mount the banana connector, the bolt and the big nut on the support:


Cut the PVC coupler to the same lenght of the big nut. Cover the nut with a few layers of electrician tape: in this way the nut fits snugly in the coupler. Mount the coupler with the help of a rubber hammer. The final result, before painting, is this:


The support varnished, ready to operation: