View Full Version : TVI filterette

12-23-2016, 07:51 PM
I am currently using a TVI filter I had years ago in the days of "glowing" finals.

I am looking at making my "go box" smaller and wondering if the new solid state finals emit lower levels of harmonics, spurious emissions, etc. so I can eliminate the TVI filter.

I can find the specs for the IC-7200 but don't know how that compares to the 2-6146's I used to use.

Spurious emissions: Less than -50 dB below peak output power
•spurious freq.; below 30 MHz: -50dB, above 30 MHz: -63dB
•Carrier suppression: More than 50 dB
•Unwanted sideband: More than 50 dB

Your thoughts please.

12-23-2016, 09:12 PM
Solid-state amplifiers need not be more nonlinear than vacuum-tube amplifiers (it's nonlinearity that produces harmonics and other spurs). Tube amps are typically class C amplifiers (very nonlinear) for CW, FM and AM, but typically class AB or sometimes class B for amplifiers that are intended for amplifying SSB signals (so-called linear amplifiers).

The real difference is often between recent amplifiers and old-time amplifiers. Modern amps usually differ from old ones mostly in having lots more filtering at the output, especially if they're no-tune amps, which are always recent.

If you're using a modern rig barefoot, or any rig with a modern linear amp, you probably don't need the TVI filter. But if you're using an old rig barefoot, or any rig with an amp that requires to be tuned up manually on each band (or part of a band), the TVI filter will help a lot and may even be essential.

If you are careless and overdrive any amplifier, the TVI filter may save you considerable embarrassment; any amp becomes nonlinear when overdriven.

I'd keep it and use it; it can't do any harm.

12-24-2016, 10:31 AM
I will second that. Properly adjusted I've never had a TVI problem, not when I used Tubes, not when I've used Transistors.
Improperly adjusted BIG TIME TVI issues.. it's all in the proper adjustments.

Now.. Many modern Solid State wonder boxes of many functions and featurs have AUTO-TUNE so they do a fairly decent job of "Self adjusting" provided everything is working... also, not all of them are properly working.

12-25-2016, 02:24 PM
Thanks for the feedback, I have had tube finals for a number of years.

I usually run the Icom 7200 at 80% max power, runs cooler and less stress on finals.

If they don't hear me at 80 watts, doubtful if 100 will make a difference in 99% of contacts.


12-26-2016, 02:01 PM
What I like is all the crybabies whining how Digital TV is not as good as Analog cause they do not understand the different bands (Many stations moved from VHF-Lo to HI to UHF)

I run 100 watts SSB for chat around the US on voice... or 40 for digital around the world.

Same everything save the microphone is a computer when I'm doing Digital.