http://www.70mhz.org/ http://www.70mhz.org/index.php?categoryid=2&p2_articleid=308 http://www.70mhz.org/index.php?categoryid=2&p2_articleid=308 70 MHz Distance Records

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]]> Sat, 05 May 2012 22:33:00 +0000 Bo Hansen OZ2M http://www.70mhz.org/index.php?categoryid=2&p2_articleid=316 http://www.70mhz.org/index.php?categoryid=2&p2_articleid=316 International 70 MHz allocations

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]]> Fri, 04 May 2012 19:47:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=345 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=345 BIPT announced that Belgium extends its radio amateur allocation on 70 MHz to include 70,2 MHz to 70,4 MHz with a maximum power of 10 W. Furthermore, the allocation on 69,950 MHz continues with its maximum of 10 W EIRP.

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]]> Fri, 04 May 2012 18:29:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=2&p2_articleid=313 http://www.70mhz.org/index.php?categoryid=2&p2_articleid=313 Regular net activity on 70 MHz

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]]> Tue, 24 Apr 2012 12:45:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=2&p2_articleid=310 http://www.70mhz.org/index.php?categoryid=2&p2_articleid=310 Beacon List

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]]> Sun, 22 Apr 2012 15:59:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=344 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=344 contest rules for more information. The contest takes place 10 June 2012, 0700-1700 UTC.

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]]> Sun, 08 Apr 2012 10:00:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=343 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=343 changes to the National Frequency Allocation Table.

We are waiting for the document to be published in the Public Bulletin. After publication it will become operational after 14 days.

The conditions will be 70,100-70,300 MHz and 20 W EIRP.

See you on the band!

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]]> Thu, 05 Apr 2012 18:57:00 +0000 Tom SP5XMU http://www.70mhz.org/index.php?categoryid=1&p2_articleid=342 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=342 frequency hearing going on in Belgium that includes an extension of the 4 m allocation. The hearing includes the "old" 69,950 MHz with a maximum power of 10 W EIRP but also a new 70,2-70,4 MHz with 10 W. The allocations will also be valid for HAREC operation. The hearing ends 6 April 2012.

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]]> Tue, 27 Mar 2012 20:48:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=341 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=341 hearing the new frequency tables between March 23 and April 2. In the documents you can see planned allocation between 70.0-70.5MHz:

http://www.ha5hrk.hu/files/FNFT2012_02_mell_fajlban.JPG
http://www.ha5hrk.hu/files/RAT2010_1_melleklet_fajlban.JPG

No date is given for when the new regulations may be effective.

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]]> Mon, 26 Mar 2012 20:47:00 +0000 Tamas HA5PT http://www.70mhz.org/index.php?categoryid=1&p2_articleid=340 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=340 ]]> Fri, 23 Mar 2012 17:38:00 +0000 Tom LA4LN http://www.70mhz.org/index.php?categoryid=4&p2_articleid=319 http://www.70mhz.org/index.php?categoryid=4&p2_articleid=319 Transverters

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]]> Thu, 22 Mar 2012 01:16:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=339 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=339 ]]> Wed, 21 Mar 2012 19:58:00 +0000 OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=338 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=338 here. Please take the time to respond. The number of responses may influence any decision.

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]]> Tue, 20 Mar 2012 18:43:00 +0000 PD0HNI http://www.70mhz.org/index.php?categoryid=6&p2_articleid=337 http://www.70mhz.org/index.php?categoryid=6&p2_articleid=337
First I tested this (second hand) PA on 144 MHz and on 13.8 V it produced max about 60 W! Perhaps the SRF 1397 is not (and never was) up to 100 Watts hi. This PA 144/100/1/2 is old and has no Preamp, so it can be that later produced PA's have a different PCB Layout....

I modified this 144 MHz PA to 70 MHz using from the “4 Meter Website” both the diagrams and remarks / description (Tnx!) given by SV1DH and GI0GDP. This modification has now become a kind of mixture....

The result is a a 70 MHz PA which has about 10 dB gain and is up to 50 W reasonable Linear and can produce about max 70 W and 10 A at 13.8 V (saturation). The idle current for the PA transistor on TX is about 250- 300 mA (see potentiometer A). Using PSK31 to measure the third order IMD I found IMD-3 at -30 dB (good) at about 15 W output on a normal (slow) Watt-meter and about -20 dB at 20 W output.

The SWR at the input is about 1 to 1 when carefully adjusting the 60 pF Trimmers at No. 2 and No. 3.

Use at the output the 3 coil/2 Doorknob Capacitor Low-pass Filter described by OZ2M or the 3 Coil/ 2 PCB Capacitor Low-pass filter of IK0VAQ. The Doorknob Filter I made here is up to 100 W easily. I saw other filter on the 4 Meter website  from G4CJZ and GI0GDP as well.

I made two photos of the modified PA with and without numbers at the places of the modifications:There is plenty of room in this PA!

By the way: Before you start take good pictures of the original PA, I did not hi. And while most of the radio-amateurs are human, like me, we can make mistakes so following this description of the modification hereunder is fully at your own risk.



A lot of the original parts can stay in place (hurrah!) , but I removed:

• At 2: remove the 470 pF ceramic capacitor.
• At7 : choice: or remove the original 60 pF trimmer or replace it with a low-loss Teflon trimmer of 60 pF.
• At 14/14A: remove the silver-mica from PCB track to Ground.
• At 17B: remove the 470 pF ceramic capacitor and put a piece of wire in place or leave the 470 pF here.

Now a few changes:
>No. 1A: cut the PCB track located under Coil 1.

>No. 1 = simple Low-pass input filter 50-50 Ohm (Tnx Elsie) with about 20 dB attenuation of 140 MHz.

4 Turns 1.3 mm CuAg 8 mm diameter, long about 17 mm  and at both sides 100 pF Silver-mica form the coil to ground. Perhaps SMD capacitors size 1206 and 50 V can also be used here.

>No. 2: 60 pF low Loss trimmer Capacitor,  probably Teflon, in series with the track at the place of the original 470 pF capacitor. Remove this one.

>No. 3: 60 pF Low loss trimmer Capacitor from the PCB track to ground.

>No. 4 : 100 nF SMD 1206, 50 volts or better, between ground and the Bias- track to the new 10 uH coil going to the base of the PA transistor.

>No. 5A and 5B: cut the track of the original PCB etched Bias- coil going from the Bias Regulation to the base of the PA transistor.

>No  5: new 10 uH coil, replaces the original PCB coil, made from an old  ferrite choke of about 50 uH 1.5 amp, by peeling 2/3 windings of.
 
>No. 6 A: cut the PCB track under the coil at No. 6.

>No 6:  Coil 2 turn 1.3 mm CuAg 8 mm Diameter, long 9 mm

>No. 7: 60 pF Trimmer Capacitor from PCB track to ground

>No. 8: just under and beside (left) of No. 7,  a 470 pF SMD 1206 from PCB track to ground or use the removed 470 pF ceramic C.

Leave about 25mm PCB track between Capacitors No.7 / 8 and the base of the PA Transistor .

>No. 9: New collector coil 8 Turns 1.3 mm CuAg 6.5 mm diameter, long 18 mm

>No. 10: 2 x 100 nF SMD 1206 and 2x 4n7 SMD 1206, 50 volts Capacitors from collector-coil No. 9 to ground.

>No 11a: Cut the PCB track between the two sets of the original silver-mica capacitors (at the collector side of the transistor) and place here coil no 11.

>No. 11: Coil 1 Turn 1.3 mm CuAg 1.3mm, about 5 mm long

>Leave between the end of Coil 11 and the capacitors at no 12 about 25 mm PCB track and cut it there at 13 A.

>No. 12:  2 x 180 pF brown Silver-mica 500 volt from PCB track to ground.

>No. 13 A: Cut PCB track under coil No. 13

>No. 13: Coil of 4 turns 1.3 mm CuAg diameter 6.5 mm, long about 10 mm.

>No. 14/14 A: Remove

>No. 14: Small low loss 10 pF Teflon trimmer from coil 13 to ground.

>No. 15 A: cut PCB track under Coil 15.

>No.15 : Coil 4 turns 1.3 mm CuAg Diameter 6.5 mm, long 10 mm

>No. 16 : Small low loss 10 pF Teflon trimmer from coil No. 15 to ground

>No. 17a: cut PCB track under 60 pF air-trimmer.

>No. 17 : 60 pF air-trimmer.

> No. 17 B: Originally there is after this coil No. 17 an 470 pF capacitor place in series with the PCB track. I removed this one and connected both sides of the PCB track with a piece of wire. Perhaps this (original) capacitor can stay.

>No. 18: Not (yet ?) solved, is the VSWR shut-down now, never tested it when the PA was still original though for the 2M Band. Did a short test without a dummy connected at the output, but the shut-down did not work, but the PA is still ok though hi.

>at A: Resistor trimmer for the Idle Bias current. Fully Anti-clockwise first (lowest current without any RF drive) then move the trimmer a bit up clockwise so that there is an increase in current of 250-300 mA (at 13.8 V).

>at B: Resistor trimmer for the Vox-delay. Put it at about 2/3 clockwise, Delay is ok then. When put to much anticlockwise, so with very short delay, I had problems that it would fall off
sometimes....



Success, it looks a lot of work but it is not!

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]]> Mon, 06 Feb 2012 01:11:00 +0000 Paul PA0OCD http://www.70mhz.org/index.php?categoryid=2&p2_articleid=307 http://www.70mhz.org/index.php?categoryid=2&p2_articleid=307 Most Wanted VUSHF DX including 70 MHz squares and DXCCs

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]]> Wed, 01 Feb 2012 20:58:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=336 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=336
Please be informed that, following our extraordinary authorization request for amateur radio propagation experiments in the 70 MHz band, submitted to the Economic Development Ministry - Telecommunications Department, the General Directorate for Electrical Communications and Broadcasting Services, Division II, has authorized said experiments in period 1 February - 31 December 2012.
The experimental campaign will be possible thanks to the participation of the ham radio community , with stations scattered all over the globe. In particular, activities will be aimed at experimenting the transequatorial and the sporadic-E propagation mechanisms.

Prof. Piero Tognolatti

More information can be found here here.

Tony, I0JX, reports that the I0JX/B beacon is also back on the air. Tony also informs that the permit includes the Sovereign Military Order of Malta and the Vatican. Although not yet announced, one should reasonably expect that also the San Marino hams are authorized to operate on 70 MHz (as they were during all the past Italian experimental periods).

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]]> Wed, 01 Feb 2012 19:22:00 +0000 OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=335 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=335 Furthermore, will the beacon OK0EE continue its operation in 2012 too.

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]]> Fri, 30 Dec 2011 21:27:00 +0000 OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=334 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=334 Regeling van de Minister van Economische Zaken.

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]]> Fri, 30 Dec 2011 13:33:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=333 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=333 Please note that the authorization has not yet been issued at the time of writing!

The University of l'Aquila announces that the military authorities have accepted their request to carry out experiments on the 70 MHz band:

Experimental radiopropagation activities on the 70 MHz band
Students of the concerned courses please be informed that, following an extraordinary authorization request for experimenting radio propagation in the 70 MHz amateur band, forwarded to the Ministry of Economic Development - Department of Communications, the entitled military office expressed its agreement to the requested authorization, which will be valid 1 February through 31 December 2012. We are awaiting the completion of the authorization process on part of the Ministry.

The experiments will be possible thanks to the participation of the worldwide amateur radio community with their stations scattered all over the globe. We will try to exploit, in particular, the tropospheric and
sporadic-E propagation modes.

Professor Piero Tognolatti (I0KPT)

Director of Electrical Engineering and Information Department, and full Professor of Electromagnetic Fields at the Università dell’Aquila.

More information in Italian.

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]]> Sun, 25 Dec 2011 22:44:00 +0000 Bo OZ2M http://www.70mhz.org/index.php?categoryid=1&p2_articleid=332 http://www.70mhz.org/index.php?categoryid=1&p2_articleid=332 The beacon hardware is a Storno CQF 632 prepared by Henning, OZ1JXY.

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]]> Fri, 23 Dec 2011 18:20:00 +0000 Bo OZ2M