[AMPS] impedance of nichrome lower

Fri, 12 Sep 1997 06:37:45 +0000

> From:          km1h@juno.com (km1h @ juno.com)
> Subject:       Re: [AMPS] impedance of nichrome lower
> Date:          Thu, 11 Sep 97 18:50:27 +0000

Hi Carl,

Here's something to mull over, since you opened the door...... 

> Another point that disturbs me greatly is that the AG6K suppressor  in
> the N7WS article does not come even close to matching what is shipped in
> Rich's kits or  in his 2-11-96  5 page flyer.            Rich....am I
> missing something basic here??

You haven't missed a thing carl. N7WS tested a totally different 
suppressor that had more inductance and shunt resistance than the 
stock AG6K unit, and compared that to a purely stock Ameritron 
suppressor he received from the factory!

> Wes wound 4.5 turns of .25" id and adjusted for  90-110nh at 10MHz.
> Nowhere in any AG6K paperwork can I find that configuration. It appears
> to be more in line with a 572B/811A  suppressor and NOT the supposedly
> apples vs apples 3-500Z  type since the W8JI supplied one was from the
> AL-80B. 

Amen. Rich just "forgot" mention that fact, just as he "forgot" to 
put the data on his Web page. 

Now think of this. Despite the nichrome being made better than 
normally shipped, the two suppressors came out the nearly same!

Peel off some turns and add a lower shunt resistance, as per the 
**real**  AG6K suppressor, and watch what happens to the system. 
Suddenly the bone stock AL-80B suppressor is MUCH better at VHF when 
in the actual circuit!

All the people who send in $14.95 (or whatever) are really getting is 
a less effective VHF suppressor than the stock AL80 type suppressor. 
On the positive side, the AG6K parasitic suppressor doesn't hurt much 
in the AL-80, because the amp is so stable it's tough to get some of 
them to oscillate without ANY suppressor.

When I was intentionally starting oscillations to see what damage 
they might cause, I had to lift two of the three grid pins off of 
ground to get several AL-80's to oscillate. 

The nichrome hype really doesn't bother me at all, except for the wild 
claims the oscillations do all sorts of damage. The "oscillation 
damage theories" mislead people and cause them to NOT understand
how PA's work. In my view that is a real shame.

> Yet the AG6K versions I have here in my hand and supported by the
> accompanying paperwork are a 3.5" long U shaped loop with a stated value
> of  60-70nh. (L Meter freq not specified).  They are also shunted by two
> paralleled 100 Ohm resistors, not just one as in the review.

Woops. There goes the VHF performance. Less inductance and 
less ESR makes a poorer suppressor, at least outside a Hollywood 
movie.

>  IMO, this appears to throw a big WHOA into the discussion. Just what did
> Wes measure???

Wes measured a nichrome chinese copy of the AL-80B's stock 
suppressor Carl. As you and I both know, a hairpin loop has less R 
and less L, so the suppression will be less with the hairpin. All the 
Web page and internet bragging about the Rp is meaningless, not just 
because the suppressor Wes measured was NOT the suppressor Rich sends 
out.... but because Rich has the whole thing BACKWARDS anyway. That's 
why Wes, a normally calm person from what I have seen,  had a fit 
with Rich.

I measured the stock Measures suppressor in a Ten Tec Titan, and it 
had MORE VHF anode Q than the stock Ten Tec unit! In the AL80A 
Rich's "low Q" suppressor DOUBLED VHF Q at 200 MHz!  

I'd be happy to supply a loaner AL80A or AL80B, and a loaner pair of 
3CX800's (Titan or equal), to any independent person with a Network 
analyzer or good quality Impedance meter who wants to measure the 
in-amplifier Q at VHF, and the system loss at HF. I have the stock 
suppressors for both, and the REAL AG6K hairpin suppressor and 
instructions (as sold to those who "thought" they were getting less 
VHF Q and a better VHF suppressor).

Wes was ready to do that, but when Rich started re-writing Wes' data 
and calling Wes dishonest, Wes got angry and bowed out. That was too 
bad, because it would have either supported or disallowed ALL 
claims.

> At this moment I think we need to consider a new evaluation from a less
> involved and seemingly biased source. I would suggest a test at the ARRL
> lab that is witnessed by at least a representative of both sides.   

The ARRL went through all this stuff with independent people when 
they were looking at the Handbook articles Carl. Why do you think 
they distanced themselves from all the stuff they printed in QST? 

When I called QST after Rich's first article, I was steered to Chuck 
Hutchenson. He told me QST doesn't get involved in technical 
disagreements and I should contact Rich so Rich could "explain" his 
theory to me. You can see, by reading Rich's posts here, just how 
"technical" and non-personal a conversation with him can be. I 
was told I was the only one disagreeing, yet years later I learned 
several people objected to technical advice, including Eimac.. 

The reason the ARRL finally changed opinions is simple and not at 
all sinister. When Handbook material written by AG6K went out for 
review, and they got a stack of negative responses, they finally 
thought Eimac and the others must have been telling the truth.

> I would appreciate some meaningful commentary from multiple sources
> please.

You have friends at HQ. Ask them how tall the stack of responses was 
and what pile (good comments vs no good) was by far the tallest, and 
who checked out the material.

Look at Dejanews, and count the people whom were in technical 
agreement with Rich on rec.radio.amateur.homebrew in the open 
forum. You need to be able to count only to one. QST found the same 
thing.
73, Tom W8JI

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