>
>--- ad5gb <ad5gb@myway.com> wrote:
>> Therefore, I'm curious to know if there are others
>> on this reflector who've experienced similar problems (any brand
>> amplifier) that have been successfully solved with the AG6K ( or
>> another design ) VHF supressor. To round out the study, one would
>> also need to know if someone had installed such a thing and found
>> that it *did not* solve the problem it was intended to correct, or if
>> it caused other problems.
>>
>
>I'm glad someone finally asked a question like this. I'm curious of
>the results as well. Here's my story:
>
>Bought a used TL-922 with the 10m mod already installed. Fired it up
>and got full output, but about 15 minutes after testing, the amp made a
>horrible buzzing noise, blew one of the mains fuses, and let out a puff
>of smoke. Found the welds bad in both Eimac 3-500s. By the way, it
>defintely arced on tune-up. The antennas are a resonant Alpha-Delta
>40/75m dipole and a Gap Titan. SWR is NEVER worse than 2:1. Feed line
>is new RG-213, no lightning arrestors. Everything is grounded.
>
>Bought a matched set of RF Parts 3-500ZGs and the amp still arced on
>tune-up. Installed the extra capacitors and grid-fuse resistor, along
>with home-brewed Rich Measures suppressors.
** expect a letter from my copyright attorney.
>The amp hasn't arced,
>spit, or sputtered on tune up since. I still need to add the
>step-start, but just haven't had the time.
** One can always do the step-start mod when replacing the 922's
welded-ON/OFF switch.
>Also have a new bandswitch
>(that I haven't installed yet) since the original has carbon tracks on
>it. I also installed the filiment mod -- I have pretty high line
>voltage so the filiments were getting almost 6V. They're now down
>around the recommended 5V. I also want to install the fast (and quiet)
>switching mod.
>
>Bottom line, the mods fixed the arcing, and I spent less than $3.00.
>I'd like to ask Tom why these work -- he seems only to say that
>parasitics don't exist, and the mods don't make sense. If that's the
>case, why is my amp now working so much better? The filiment mod is
>very clear to me, same with the step-start mod. Why is this such a big
>deal?
** probably for the reason it took Ford 9-years to fix the solid-state
ignition failure problem in their gas engine powered vehicles -- i.e.,
NIH syndrome.
> If you make your own suppressors, you'll spend very little, and
>certainly won't hurt anything.
>
>Also, if parasitics don't exist or are "Voodoo", why are there
>suppressors on just about every amp or tube transmitter??
>
** Good question. However, Tom put did his reputation on the line when
he designed the only 8877 HF-amp ever that uses no parasite suppressor
whatsoever, [See Figure 24 on my Web site]
cheers, Joe
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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