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webmaster@nospam.com (G8FXM) webmaster@nospam.com (G8FXM) Tue, 07 Sep 2010 22:31:05 +0100 Tue, 07 Sep 2010 22:31:05 +0100 http://backend.userland.com/rss e107 (http://e107.org) 60 http://uksmg.org/e107_images/uklogo3_col.gif http://uksmg.org/ 88 31 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1343
Below are my thoughts open for discussion and criticism by all.


Background
At the Region 1 IARU meeting held during March 2010 in Vienna David Butler, G4ASR, proposed moving the beacon sub band from 50.000 - 50.080 MHz to 50.400 – 50.500 MHz and to allocate 50.000 – 50.100 MHz for telegraphy exclusive use.

Subsequently many opinions have been aired and the proposal in its existing form is largely opposed by UKSMG. However, in the ensuing debate two common views emerged.

Firstly, changing the beacon sub-band in 2012 does not allow sufficient time to ensure a smooth transition to the new frequencies and changes should not take place during a sun spot maxima, and

Secondly, re-organisation of the beacons offers a rare opportunity to re-examine the complete band plan.

The existing IARU 50 MHz band plan was adopted in 1984 with slight amendments in 1996 and some minor tinkering, largely on a national basis, since then.

Many new and emerging technologies need a band allocation, whilst
improving equipment specifications also have an impact.

Objective
The objective is to achieve a coherent, multi-regional resolution to the band plan issue not merely the issues concerning beacon sub band re-allocation.

It must be remembered that any band plan is voluntary but the more logical and coherent it is the more likely it is to be adhered to.

Any band plan will be a compromise and will not/cannot satisfy every special interest group.

Process
National Societies, lead by either the existing VHF Manager or by an individual appointed specifically for the task, should consult with local interest groups and individuals with specific expertise to define key criteria and a “wish list” to give an outline shape to a revised bandplan.

IARU vhf/uhf delegates should examine this information and assess the degree of communality and, taking account of any specific region requirements, propose an outline multi-regional revised band plan.

This should be referred back to the initial National proposers for comment, suggestions and development.

Regular communication between all interested parties should result in an iterative process with revised information being passed through the chain.

A revised band plan will then emerge which will, of course, be a compromise but due to the detailed two way communication all should appreciate why the band plan has the shape it does even if it does not fulfil individual wishes.

Schedule
Agreement for the new reasoned, multi-regional band plan should be reached by the end of 2014 with National Societies responsible for implementation by the end of 2017. This will include any relocation of beacons.

Conclusion
The opportunity to modify and modernise the current band plan should be wholeheartedly embraced, creating a framework for the six metre band for the next twenty-five years.
]]> g4jzs@nospam.com (David, G8LZE) Sat, 04 Sep 2010 14:55:52 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1343 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1342 g3zyy@nospam.com (Trev, G3ZYY) Mon, 30 Aug 2010 17:01:50 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1342 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1341 http://www.techvert.com/sunspot-photo-is-most-detailed-ever/
[ image disabled ]]]> la7dfa@nospam.com (Per, LA7DFA) Sat, 28 Aug 2010 13:06:48 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1341 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1340 WSPR is an easy way to take part in radio propagation experiments.

There is a growing group of amateurs using WSPR on six meters, you may be surprised what propagation is possible when the band is "dead"!

There is a very good introduction to WSPR by G4ILO at http://www.g4ilo.com/wspr.html 

You can see what propagation is being reported in (almost) real time by going to http://www.wsprnet.org Registration is free.

Download the free software and have a go. 

David]]> g4jzs@nospam.com (David, G8LZE) Wed, 18 Aug 2010 16:01:00 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1340 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1336
Tnx
Mike G8CMU]]> g8cmu@nospam.com (Mike ,G8CMU) Sat, 07 Aug 2010 11:00:04 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1336 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1334 ei7bmb@nospam.com (Tony , EI7BMB) Tue, 03 Aug 2010 13:32:43 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1334 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1329
Time ago standing on 50110 was a nice way to see if band opens just because people used it to make calls. Just what a calling frequency is supossed to be.

But lately, specially this year, standing on 50110 seems to be just a waste of time. (Almost) nobody use it. It is much better to stand on 50115, 50120 or better 50150 to see if band is open. I'm not talking about EU stations. Even when a transatlantic or TEP opening starts, people prefers to call around 50080-50090 or around 50120-50125.

So unless you have Internet connection (cluster, on4kst chat, etc) you will miss all openings, except if you are moving your dial constantly looking for weak signals. I think we are creating Internet dependency to all 6m operators.

So, I wonder if the "strict" rules about 50.110 usage are a good idea or not.

73!]]> ea4eoz@nospam.com (Miguel, EA4EOZ) Wed, 28 Jul 2010 14:21:45 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1329 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1328
Bought as a spare from Vine last year box has been opened but that is all.

£300 plus post or collect Paul G4CCZ g4ccz (@) 6metres.com]]> g4ccz@nospam.com (Paul, G4CCZ) Sat, 24 Jul 2010 21:17:09 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1328 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1327 Anyone that ever built a big V8 engine will know how much money you need to spend to get a car to run at high speed consistently.
In the case of the GMH 4.9 (5 liters) about $1000 for every 10 km/h over 200 km/h.

In the case of BEACON service 6M amplifiers or EME CW they need to be well engineered.

As I survey the latest in a string of failures dating back to 1975 of 6M CW service beacons I have been the custodian for.
The latest failure in VK3RMV has been an ICOm PS400 power supply rated at 30 amps running a Motorola Mitrek at 35 watts out.
Heat is the enemy.

In the case of any TUBE type amps when pressed into ICAS heat is also the enemy.
Forced air cooling by high speed blower maybe the solution.
The amplifier with which I set the initial VK record in 1993 was a modified Henry 2K4 in which I ran a pair of 4/400A radial beam Eimac tetrodes in parallel.
Output was Pi/L matching.
IMO the 3/500Z tubes are too fragile and twitchy.
The parameters were 4KV on the anodes at about 1 amp key down.
Output was an easy 1000 watts of CW.
The tubes ran from cherry red to black bottom to top.
The transformer was from a Dawe Microwave oven and was rated at 5KW.
I used choke input filter with just a small 2 uF cap on the output.
Critical in the design was the HT RF choke and the output matching coils.
Anode coil was 3 turns 3 inch wound over 3 inches.
The L was 5 turns over 2 inches 1 inch diameter.
Input was a 3 turn coil with a tap via a 470 pf cap to the input socket.
The wiring to the filaments was silicon and went through the insides of this coil wound bifilar.
Filaments were in series 10 volts at many amps.
Drive was from a MIRAGE 100w amp and the PA had about 10-12 DB gain.
Circulating currents make 6M tank circuits tricky to design for max efficiency.

In 1998 I acquired an engineering project from Emona which was a 20M Amp running a 4/1000A
in Class B and decided to convert it to the 6M band runnign Class AB1 grid driven and neutralised.
Using the similar Pi L matching and chokes I had problems right from the start.
Single ended is harder than parallel balanced as used in the 4/400A design and in the end running 4200 volts the best output obtained as about 1.5 kW and I barely made the 10dB gain figure.
Someone told me that from base pin to anode the tube is 11 inches long and a significant proportion of the 6M wavelength leading to phase delay and degeneration/negative feedback.
4/1000 was regarded as dated technology compared with ceramic tubes of today.

Other designs tried were a very nice converted 160M amp from VK3ZL which made 1500 watts on 6M and eventually was sold to a 2M stalwart who put it to better use on 2M EME.

I converted an MLA1200 to 6M (single 8875) which made the VK legal SSB limit of 400 watts and was used for many years by Jeff VK8GF and is still in use today by VK8ZLX/VK5PJ.
it used the single fan blowing over the fins of the 8875.
It was powered by the MLA2500 power unit and driven in Class B by an IC551D.
I used it in the 1980 and 1982 VK9XT expeditions and ran it as the VK9XI beacon for hours on end in a non air-conditioned shack at 31 degrees.
Running it put the shack up to 40 degrees.
I think I lost ten pounds in that sweat shop.

I had but never converted an MLA2500 to 6M running a pair of 8875's, which are now are priceless and not viable.

Tom VK4DDG and Joel N6AMG converted a Kenwood TL922 to 6M and ended up running an 8877 in place of the pair of 3/500Z's
The amp had serious power supply ripple at the power levels used on CW.

In 1998 I converted an SB220 to 6M in KL7 but never got to use it as there was no dx.


My current amp for the past 2 cycles is a quad bipolar TES0552G and with the recent acquisition of the MFJ 75A SM supply is quite a nice package.
I used it in 2000 in VK8 and worked heaps of DX.
It takes 75 amps of power at 13.8 volts.

It runs only 300 watts out and drive levels are to be observed or suffer the failures.

In line with current Australian RF Exposure limits....
I sold my converted Henry and dropped the EME high power permit.

The Henry still works 20 years after being converted.

IMO the experts on 8877s are GJ4ICD and K6QXY (Who runs a pair).


I would love to see a few FET high power projects or something like
Jimmy JKV OR JOEL N6AMGS
WATER COOLED DXP 1KW AMP.]]> vk3zaz@nospam.com (VK3ZAZ Steve) Fri, 23 Jul 2010 21:42:29 +0100 http://uksmg.org/e107_plugins/forum/forum_viewtopic.php?1327