Relay could be part of an electrical motor brake. Many saws have a brake circuit which causes rapid deceleration when the run switch is released. If I remember right, some electrical brake circuits short motor windings, while others inject DC voltage to the motor.

Tom, KA1MDA

My SK replacement cross reference from 1985 lists an SK3054/196 as an NPN silicon transistor, TO-220 case, used for AF and deflection. Specs are as follows:

Dissipation: 50W  Collector current: 7A

Breakdown Voltage: Vcbo:90V  Vceo:70V  Vebo:5V

Typical: hfe:70  Vce:4V  Ic:3.5A  Ft:0.8 Mhz

Pin out: B-C-E (collector connected to flange)

You can also look them up at the NTE semiconductor web site to get cross references and PDF spec sheets:
http://www.nteinc.com/semiconductors.php?a=12

Hope this helps.
Tom, KA1MDA

It all depends on the situation. All but one of my antennas were obtained second hand, including a Hustler 6BTV with a spare 80m resonator and stinger ($75), Hygain VB-66DX ($50), KLM 2M-16LBX ($25), K1FO DSFO-432-25 ($25), and a Directive Systems 2345LY (free). I got the 1296 looper for free because it had been dropped, deforming most of the elements. It took quite a while the make them all round again and lined up and spaced properly! Oh yeah, the 45 foot Rohn 25G tower was used also ($100)!

The secret is to only consider used antennas that are still fully assembled. That way, you can inspect the antenna's condition at the seller's location first, then disassemble it yourself, carefully marking the the sub assemblies. That way, you know the antenna is complete, and more importantly, you'll know how to put it together again!

Tom, KA1MDA

"He only has a VHF version listed (88-110 MHz)"

Since this frequency range is used for FM broadcasting, bear in mind it may very well be a class C amp and not useable for SSB without altering the biasing.

If you're interested in monitoring battery capacity, a volt meter is virtually useless. You need to cumulatively measure actual charge/discharge current through a shunt.

A device from Bogart Engineering called the Trimetric does exactly that, and can be found at the following link:
http://www.bogartengineering.com/products/TriMetric

I've been usng a Trimetric TM-2020 for years to monitor the charge status of my emergency power backup system, and have found it to be extrmely accurate and useful. Link to my emergency power system is below:
http://www.ka1mda.org/ham/homebrew/ups/index.htm

Tom, KA1MDA
www.ka1mda.org

I don't have any experience with this amp, but do have a lot of experience with industrial electronics and step starts in RF induction welders, heaters, and VFD's. Usually, when a set of relay contacts welds shut, it's due to the back EMF of a highly inductive load creating a high voltage spike and associated arc across the contacts as they open, not from high current draw when they close. In industrial equipment, the usual quick fix is to attatch a quencharc across the load, as close to the load as possible. Quencharc is the brand name of a small blue component that consists of a series RC circuit, usually something like a 200 ohm resistor and a .1 uF cap. The generic name I believe is a snubber. Don't know if that will help, but might be worth a try.

As for the humming and heating while the amp is off, sounds like there might be more problems... have you checked the continuity of the amp's main switch/breaker? Could there be a possibility one or more poles are also welded shut, perhaps after a lightning strike?

Tom, KA1MDA
www.ka1mda.org

Most of the linear power supplies I have repaired which blew fuses on power up were all caused by the same failure-  a shorted rectifier diode. Every time the supply is turned on, the rectifier diodes take the biggest stress as the discharged filter caps draw a huge inrush current as they charge up.

The best way to diagnose is the divide and conquer method. Disconnect the leads from the DC terminals of the rectifier, and try switching the supply on. If the fuse still blows, disconnect the transformer leads from the rectifier and try again. If the fuse does not blow, it's the rectifier that's bad. If the fuse still blows, the problem is in the transformer.

If the fuse didn't blow with the DC leads disconnected from the rectifier, reconnect them, then disconnect the leads going from the filter cap to the pass transistors, leaving just the rectifier and filter cap in circuit.  If the fuse blows, you have a shorted filter cap. If the fuse doesn't blow, check the pass transistors.

As I mentioned in the first paragraph, I've never had to troubleshoot beyond the rectifier- it was a shorted diode every time. I usually replace them with a bridge rectifier rated for 40A @ 800V. Sure the ratings are overkill, but it only costs a few bucks more than a much lower rated unit, and guarantees it will never fail again!

Tom, KA1MDA
www.ka1mda.org

I wouldn't worry about maximum input voltage as a determining factor in selecting a counter, as that's probably the least important spec to consider. In fact, I installed back to back diodes across the inputs of my counter to limit maximum input voltage to .7 volts to protect the counter and prescaler. One normally attenuates signal levels to suit the counter, as opposed to selecting a counter with higher input levels to suit the source.

According to their on line advertising, they list the time base stability as "<5 ppm". That's pretty crappy, especially if you're going to measure UHF and higher frequencies. The timebase is also 20 Mhz instead of the standard 10 Mhz, which makes it useless for slaving other equipment to, or using an external 10 Mhz GPS timebase with the counter.

I didn't read manual (the download link was broken), but just because a counter has 2 input jacks doesn't make it a dual channel counter. Most counters use multiple input jacks to offer direct and prescaled inputs, with differing input impedances, like 1 Megohm and 50 ohms. Unless you can use it to measure time interval between inputs, it's still basically a single channel counter.

For comparison, my 20+ year old Digimax D1200 counter specs the 10 Mhz timebase at +/- 1 ppm (20-40 degrees C), with an aging rate of 1 ppm per year.

If I were buying a counter, my first concern would be the time base accuracy. Next in line would be the ability to use an external time base, and then input sensitivity, followed by features like the ability to do period and interval measurements.

Tom, KA1MDA
www.ka1mda.org

"My main point is that people need to use something called discretion"

Discretion is great, as long as what you are doing remains within the law. Once you cross over into the realm of illegal activities, that's a whole different story and discretion has nothing to do with it.

Isn't the concept of using discretion to justify doing something outside the law the very reasoning that caused the Enron meltdown and the Wall Street crash? I bet the individuals responsible for those fiascos felt just as strongly as you do that the rules they were breaking were silly, outdated, and inconsequential. Should we begin using such "discretion" when approaching stop signs or traffic lights?

When someone speaks about "using discretion" when doing illegal things, it's not discretion- it's self dillusion in an effort to justify doing something they know is wrong.

"before getting my license (all I use it for is emergency communications, ARES, & marathon mile marker reporting so I'm far from "electronically inclined"

Welcome to the NEW ham radio- courtesy of the latest ARRL initiatives. This is a perfect example of types of "hams" (and I use the term loosely) that result from the rush to fill the ranks with question pool memorizing em-com'ers.

I am not sure which region of the world you are from, but in the USA, 70 cm offset is 5 Mhz, and the FM band is between 440-450 Mhz. According to the user's manual, this radio has a frequency range on 70 cm of 430-440 Mhz. Since there are no repeaters in the US in that part of 70 cm, the offset really doesn't matter, as there is no place to utilize it (assuming you're in the USA). The 2m frequency coverage is listed as 144-146 Mhz, which leaves out the upper 2 Mhz of 2 meters as well. If you are in the USA, this radio appears to be designed for a different country and will be of very limited use in the USA on 2 meters, and of virtually no use in the USA on 70 cm. - and that is if the optional PL board was ever installed.

According to the schematic diagram for the headset, the mic has an internal amplifier. Did you supply DC bias to the mic element and amp? Here's a link to an adapter I built to get a Telex noise cancelling headset to work with my TS-2000. Maybe it will be of some help..

http://www.ka1mda.org/ham/homebrew/telex/index.htm

73, Tom

I would want it to have all the features of my Kenwood TS-2000X.. maybe throw in a really nice general coverage receiver, maybe HF band coverage.. and it should be priced well below the cost of an Icom 910..

Oh , wait- the TS-2000X already does all that, and already sells for way below an Icom 910..

Great photo! However, one minor technical clarification for the photographers: I believe that's a TIME EXPOSURE photo, not a time lapse. The two are very different.

Tom, KA1MDA

You may be able to use your AZ/EL telescope mount to track satellites in real time using a program called Satellite Tracker. It's available for free download after joining the following yahoo group:

http://tech.groups.yahoo.com/group/satellitetracker/

I've downloaded it and it interfaces to my Celestron Nexstar mount with no problem. It's pretty amazing to watch the scope slewing over to the AOS point and then tracking the birds in real time! Assuming the mount can handle the weight of the antenna, it should work great!

My only problem is updating the Keps. Satellite Tracker uses Space-Track for downloading TLE's, which requires the user to create a login account. My account hasn't been approved yet. For now, I've set up Satellite Tracker to load kep files from my SatPC32 directory, which has solved the problem until my account gets approved.

Ooo- just got my SpaceTrak account approved, will have to try it out and see if it updates keps automatically now!

Tom, KA1MDA