Also agreed. Build rigs with as few custom parts as possible.

HA5RXZ

Replace one pane of glass in your window with a perspex or lexan sheet, available from any hardware store. This can be drilled with as many holes as you want for antennas and control cables.

HA5RXZ

A power supply generating 100 to 150 amps at (I presume) 13.8 volts can be done but you need to be VERY careful with the engineering as high currents are involved. Here are some hints.

1) If it needs less than two people to lift it it's not big enough. I have a fifty amp supply in my shack and lifting it off the bench is a struggle. 150 amps at 13.8 volts is over 2KW so take a look at a 2KW amplifier supply to give you some ideas of scale.

2) Forget about the choke idea as it will drop too many volts under load. Use lots and lots of good low-esr capacitors as smoothing. Don't forget bleeder resistors across the capacitors.

3) The transformer is going to be a biggie. My supply uses the filament transformer from an industrial X-ray machine and if you can't find one of these then contact Peter Dahl.

4) This is going to be expensive. As an exercise I looked up the cost of a suitable bridge rectifier and it's $80 (eighty bucks). Add to that the cost of the transformer and capacitors plus the regulator circuit.

5) Use lots of regulator transistors rather than a few big devices. Make sure there is lots of heatsinking, the supply should be warm under load and not hot.

6) Forget about fuses. a 150 amp fuse will take about ten seconds to blow and during this time a lot of nasty things might be happening. There are various high-current protection circuits around but if you can't find something suitable then email me.

7) Safety, safety, safety.

HA5RXZ

If Osama manages to set off a nuclear device within 20 miles of your QTH then working the DX on 80m is going to be a low priority. However, I suppose you deserve a more technical reply.

A nuclear blast generates something called an Electromagnetic Pulse or EMP. Think of it as the world's biggest lightning strike. If your site and equipment is already lightning proof then the front ends may survive. Rigs using tubes are not affected by an EMP and this can sometimes lead to some surprises.

A number of years ago a Soviet fighter pilot defected to the West and landed his (brand new) fighter jet in an airport in Japan. When the USA engineers pulled the plane apart they found that the electronics were tube based. Initially this was laughed at until someone pointed out that all of the electronics in the plane were EMP proof and the Soviets might be the only people in the air after WWIII.

HA5RXZ

You're right, connecting rig power to the cigarette lighter socket is a bad idea.

See http://www.k0bg.com for lots of ideas.

HA5RXZ

The ratio of 1.5:1 is correct if one impedance is 2.25 times greater than the other. I'm not sure about your balun construction though so I will leave others to comment about this.

If your balun does not work as expected then get a large ferrite ring (about two inches in diameter for transmitting work) and just put four turns on one side of the ring and six turns on the other. You may need to experiment with the number of turns but keep the same ratio.

If the finances don't stretch to a two inch type 2 or type 6 core then try the ferrite core from a scrap TV Line output transformer.

HA5RXZ

Looking for an application circuit or a datasheet for the above chip manufactured by NEC until 1995. As usual, a search on Google finds hundreds of companies willing to sell me the part but none with data.

HA5RXZ

Try sending a message to the Foxtango website, you might get more folk interested.

http://foxtango.org/foxtango001.htm

HA5RXZ

Please don't do this.

1) The windload and vibration will loosen the mortar in the brickwork and your chimney may fall.

2) With the antenna installed you now have a big lightning rod on your chimney. Do you want this?

3) If your chimney is still in use the antenna will get coated in soot and debris.

4) If something bad happens this may affect your house insurance.

5) With the antenna mounted on the chimney you will have problems creating and installing an effective set of radials. Without the radials the antenna will not work correctly.

HA5RXZ

Well, your post is a little vague but I will have a go:

WWW.RIGPIX.COM
Radios are sorted by manufacturer then model number. Some radio pages also have service information but not all. If you have any additional information just email the webmaster, SM0OFV.

WWW.GOOGLE.COM
Just search by model number. There's a lot of rubbish out there but there's a few decent sites.

WWW.MODS.DK
Lots of modifications for virtually every rig on the planet.

WWW.HAM.DMZ.RO
Some useful stuff

HA5RXZ

I don't know this rig internally but I have a few suggestions.

1) Have a look at the circuit diagram and see if the tuning and RIT connect to a common point anywhere, it could be an IC or a connector. Check it.

2) The tuning control is almost certainly an optical encoder, the RIT control might be. Most encoders are the slot type so look for two pins on one side with about 2V across it (LED) and three pins on the other side (two signals plus ground or supply for the detector)

3) Software problem?

HA5RXZ

The top of the article section at the moment has the third piece from W6TH. The quality of this article is questionable at best and so I would like to propose the following:

Alternative #1
Eham appoints a number of moderators who can review articles before publication. If an article is of questionable merit then it can be passed on to a second moderator for another opinion.

Alternative #2
The article is published but if more than (say) 50% of the comments are bad then the article is removed.

Comments?

HA5RXZ

The housings for 15, 30 and 45 amps are the same size, the only things that change are the size of the contact inside and the diameter of wire it can accept.

HA5RXZ

The 5 volt windings are to supply the filament and the HV connectors at the top are for the HT. Any tube that has a 10 amp filament requirement is going to be a VERY big bottle.

My guess is that your transformer is from an x-ray machine.

HA5RXZ

If you go to the Powerwerx website you'll see some brackets that they sell just for this. They have prongs which fit either side and in the small holes normally used for the roll pins.

Full details on http://www.powerwerx.com/category.asp?CtgID=1679

HA5RXZ