Ten bucks for a gallon of mineral oil at your local farm supply store.

I once purchased bulk lots of transformer oil.  It was supplied by one of the big oil companies - Phillips 66 maybe - I asked them what it was made from.  They said they started with standard mineral oil and filtered it extra and ran it through a heating process to drive off the more volatile components.  They said this raised the flash temperature by about 10-15 degrees.

There is a new, very expensive, silicone-based transformer oil, but it's not used much, at least not yet.

AM

Here's another one of many famous "really really really bad bits of advice".

It is NOT true that an interface "does no harm".

If you're using an old enough amplifier that it's got high voltage and/or current in the T/R line, then it's a given that the amplifier has a rather slow, clunky, old open-frame relay in it.

Such amps have such slow transmit-to-receive and vice-versua delay times, that you are guaranteed to hot switch.  In short, there will be a brief interval where your exciter is transmitting into an open circuit, and another brief interval where the amplifier is destined to be transmitting into an open circuit.  

You can avoid this by driving the amplifier with a same-generation old tube radio that also has a slow mechanical relay.  Or, if using modern solid-state gear, you have to correctly sequence things.

I have an outboard keying system whereby I FIRST key the amplifier, then the exciter, with a controllable delay time between them.  My key and/or mic plugs into the external keying system.

What's wrong with the outboard interfaces?  They all make the delay worse.

Sure, you can add an outboard interface.  That will prevent your exciter's relay from welding shut or burning open.  But eventually, the screwed up timing will cause your amplifier tubes to arc, and then you'll be receiving bad advice on using nichrome parasitic suppressors and other voodoo nonsense.

AM

If, during tune-up, all the voltages are correct, and the plate current dip and grid current peak behave as the instruction manual says, then you must be getting RF output.

Check your wattmeter.

AM

Be aware that hams who attain WAS and DX from nets are known as "list lizards".  Not quite as bad as a lid, but along the same lines.  Use a search engine to search for the phrase "list lizard" and you'll get an idea.

The problem is this: a valid QSO, in theory is made directly between you and the DX or needed state.  The net control, unfortunately per standard procedure on these nets, provides a service that too often is a relay.  A real clue is when you here "when last heard, 53".  A valid QSO really requires the two of you to be able to exchange info in at least near real-time.

County hunters have nets - you could check into those and find all the states you need in a matter of days.  The procedures used in the county hunters nets are often more well thought out, and the contacts are always real.

As another reply on here said, it's very common to use contest to add to state or country totals.  In fact, that is one of the most common ways that people become contesters, to look for states/countries during the 'test.

AM

There's no way to guarantee that the antenna won't mar the finish.  I've even tried the Saran Wrap trick and still got indentations in the paint.

Here are the various options.  Top one is best, following that they get lower in usefulness.

1) Own a car that's old enough that you don't care about the paint
2) Own a car that's at least three years old.  The paint continues to harden as it ages
3) Use a bumper mount
4) Use an inside antenna

AM

The only time that a forced-air cooldown is useful is if the tube involved has a very high power filament or heater, and the thermal conduction path to the outside air is poor.  This is true for some of the 100kW and larger tubes, but not true for anything used in the amateur service.

AM

If the replacement antennas you're using still plug directly into the handheld, and do not have any sort of "ground plane", then they're not much help.

You need a "real antenna".  This would be a vertical with some sort of counterpoise/ground plane.  It should be outdoors, not indoors, and the higher the better.  Ten feet high should be enough.

Once you've done that, you will be able to reach nearly any repeater you hear.

AM

Maybe I just don't understand things....why does the amp have five microprocessors?  Will those added microprocessors make the signal sound louder?  Will they make it tune from one band to the other more quickly?  Will they make the amplifier cleaner?

Seems to me that adding more microprocessors means there are more parts to fail and more cost to build it.

One microprocessor can take the place of many discrete digital logic parts, and makes sense.  I can't understand five....

Sounds a lot like "buy this AM radio because it has TEN transistors instead of NINE" - remember that from the 1950s transistor radio era?

AM

Doing it right the first time is not the best way to learn.  You learn best by giving it your best shot, seeing what worked and what didn't, then adjusting what you did to make it work the way you want.

As far as crimp/solder versus solder, I've seen it done both ways.  There isn't a "best" way, nor a "worst" way.  It's a matter of what you're more comfortable doing.

Given that you have a concern about doing it right, I'd suggest not crimping.  If you solder without crimping, then decide to change something later, you can use solder-wick to remove the solder, and move the wires around.

AM

Using a Hewlett-Packard Network Analyzer, I verified that a UHF connector is electrically invisible to about 2 GHZ, despite claims to the contrary.  A new BNC connector and an N connector have identical performance, as they exhibit the same interface dimensions.  Both N and BNC, when installed correctly, are useful to 18 GHz.  Far better than a UHF connector, but only microwave enthusiasts need to care.

The typical UHF connector is more rugged than the typical N connector, therefore my ham station purely uses UHF connectors.

The type N connector makes an "instrumentation grade" repeatable connection, and UHF does not, therefore you won't find UHF connectors in a cal lab.  But again, as hams, why should we care?

UHF is still the standard connector used in AM broadcast stations of 5kW and less.

AM

You haven't told us the symptom yet.  Are you intermittently seeing high SWR somewhere or intermittently seeing no RF output, or intermittently having the receiver go dead?

Help us help you.

AM

Remember that the FTDX-9000 was rumoured to have two versions?  Yaesu reps told me (about a year and a half ago) that the lower powered version would be called the FT-2000 and the higher powered version would be called the FTDX-9000.  The '2000' nomenclature is intended to suggest it is the successor to the FT-1000, and the '9000' nomenclature is intended, frankly to be "bigger than a 7800".

AM

The third harmonic in a normal amp is not generating any appreciable power.

Power requires in-phase volts times amps.  Even if there is a 3rd harmonic current (amps) at the anode, the narrowband pi network ensures that there is not a third harmonic voltage.  

The third-harmonic parallel "trap" which he refers to turns a class C amp into a class F amp, in the solid state world.  It's a way to make the collector waveform more closely resemble a square wave.  In the solid-state world, we think of it as a way to squeeze an extra 10-15% out of an already-optimized class C amp.

Its effectiveness is dependent on the amp already operating close to saturation; a class AB amplifier (such as is required for SSB) won't enjoy as many benefits, and it doesn't do a thing for an amp that's operating substantially below saturation.  Also, because it will have an impact on gain only near saturation, it would lead to increased IMD.

Most efficiency-enhancement techniques require the amp to be operating in saturation to begin with.  We hams are the odd lot, because we are the sole survivors who don't use Class C amps.  The entire commercial world operates with AM (plate modulated class C) or FM (class C).

AM

The pi network presents a very low impedance to that third harmonic, which is what a trap would do, so we already have that feature built into ham amps.

AM

You didn't mention whether this was HF or VHF.  If HF, though, the answer would be thus...

Your antenna and radio receive an electromagnetic stew containing a mix of signals (desired), broadband noise/hiss (undesired) and static/thunderstorm crashes (undesired).  For any of today's radios, or for that matter any radio made in the past 30 years, this muck arrives at the receiver with great strength compared to the very tiny signals which the receiver is capable of receiving.

What you hear psychoacoustically is a signal, with some noise in the background.  If you attenuate the electrical energy from your antenna to the receiver by, say, 20dB, due to poor SWR, then both the desired signal and the undesired noise are attenuated by the same amount.  Your ear still hears a signal with noise in the background.  If you attenuate even further, and you finally reach a point where the intended signal strength starts competing in weakness with the radio's internal noise, then you will begin to notice the difference.

This is one reason why we cannot evaluate antennas on the basis of reception - receivers are so sensitive that they can hear quite a bit with no more than the thought of an antenna connected.

AM