Parasitic suppressor data

Parasitic suppressor data

Post by Wes Stewa » Sun, 12 Jan 1997 04:00:00


As promised, I'm posting the data you all have been breathlessly awaiting.

It is on my home page (which is the first time I've done this) at:

http://www.azstarnet.com/~n7ws

I hope it works!

73, Wes -- N7WS

 
 
 

Parasitic suppressor data

Post by Chuck KD9J » Mon, 13 Jan 1997 04:00:00



> As promised, I'm posting the data you all have been breathlessly awaiting.

> It is on my home page (which is the first time I've done this) at:

> http://www.azstarnet.com/~n7ws

> I hope it works!

> 73, Wes -- N7WS

FYI:

Wes...Your Home Web Page wants a userid and password!

Chuck   KD9JQ

--
---------------------------------------------------------
 Charles H. Reichert             847-358-3827  Home    
       KD9JQ                     847-632-6669  Work
  955 Concord Lane           http://www.imaxx.net/~kd9jq

---------------------------------------------------------

 
 
 

Parasitic suppressor data

Post by John Siege » Mon, 13 Jan 1997 04:00:00



> > As promised, I'm posting the data you all have been breathlessly awaiting.

> > It is on my home page (which is the first time I've done this) at:

> > http://www.azstarnet.com/~n7ws

> > I hope it works!

> > 73, Wes -- N7WS

> FYI:

> Wes...Your Home Web Page wants a userid and password!

> Chuck   KD9JQ

> --
> ---------------------------------------------------------
>  Charles H. Reichert             847-358-3827  Home
>        KD9JQ                     847-632-6669  Work
>   955 Concord Lane           http://www.imaxx.net/~kd9jq

> ---------------------------------------------------------

I found that just not entering one still allowed access to the link.
73 John
 
 
 

Parasitic suppressor data

Post by Wes Stewa » Mon, 13 Jan 1997 04:00:00



>Subject: Re: Parasitic suppressor data
>Date: Sun, 12 Jan 1997 09:54:38 -0600

>> As promised, I'm posting the data you all have been breathlessly awaiting.

>> It is on my home page (which is the first time I've done this) at:

>> http://www.azstarnet.com/~n7ws

>> I hope it works!

>> 73, Wes -- N7WS
>FYI:
>Wes...Your Home Web Page wants a userid and password!
>Chuck   KD9JQ

I dunno...

I called my ISP and they were baffled.  The support guy did change the link
address to the complete path name so maybe that will help.

Others have said to input anything (or nothing ) for a password and it works.

Sorry about the problem.

73, Wes N7WS

 
 
 

Parasitic suppressor data

Post by w8ji.. » Thu, 16 Jan 1997 04:00:00

Quote:>>Extracted from E-mail>>

The suppressor graphs (RL.GIF) seem to show two things:

1. The conventional (non-nichrome) suppressor gives a faster roll-off of
Q with frequency than the nichrome suppressors.

2. There's very little difference between the two grades of nichrome.

You obviously don't want to get publicly embroiled in this controversy,
and neither do I. However, it does seem that the distinguishing feature
of the nichrome suppressors is their low HF Q.  The VHF Qs are all
pretty similar.

The VHF Q of the conventional suppressor could be made exactly the same
as the nichrome ones by changing the value of either L or R, but the HF
Q of the conventional suppressor would still be about a factor 2
higher.<<-<<

I don't blame anyone for avoiding Rich's wrath. But since I am already on
his top ten list, I have nothing much to lose, hi. So I'll post this and
accept the return attack it will almost certainly generate.

This conclusion above is the same conclusion I reached, nichrome
suppressors offer lower HF Q, and nearly identical VHF performance. Just
the slightest adjustment in resistance or inductance of the conventional
copper wire suppressor would result in less VHF Q without greatly changing
HF Q.

If the data is reviewed, the ratio of Q is almost unity at 200 MHz and
over 2:1 at 10 MHz. Just the slightest adjustment of R or L will make the
conventional suppressor equal the nichrome at VHF, while maintaining
better Q at HF where we want losses to be reduced.

For example, the AL-80B oscillates at about 170-180 MHz when the
suppressor is removed. At that frequency, Wes measured a Q of about one
(same as I posted weeks ago). The Q of a duplicate nichrome suppressor is
about .75. This very small Q change is diluted by circuit effects when the
suppressor is installed in an actual PA. The actual operating Q change
would be even less at VHF, and more at HF.

Rich's claim this small change in VHF Q is a great or worthwhile
improvement that cures all woes is completely false. Anyone believing that
would have to have a real problem understanding parallel and series L/R
circuits. Add one turn to the conventional suppressor or adjust the
resistor size, and you've gone even lower with Q than the nichrome.

Finally, I'd like to remind everyone how (over and over again) Measures
squaked about how he could SEE the difference in his dip meter, describing
all the sharp dips that went away when he made (what amounts to) a *very*
small Q reduction at the frequency of interest. Rich would have use
believe he measured a Q change of less than 0.5 with his GDO!

Remember and compare those claims of what he "saw first hand" to other
claims of things he "knew for a fact":

1.) The Miklos employment tale. He claimed he "called Eimac" and they told
him Buzz was never R+D manager. Yet Eimac even issued a letter (after
getting Buzz's permission) explaining Buzz was indeed R+D manager. Not
only that, VHF Handbooks list Buzz as Eimac's former R+D Manager. Even
after the employment confirming letter was out, Rich sent Buzz Miklos a
post card telling Buzz he was never R+D manager!

2.) The tale about Marvin Born. Rich said Marvin measured parasitics in an
AL1500. Turns out it wasn't even an AL1500, it was a dual 8877 PA built on
a old empty prototype chassis. When I talked to Marvin he said he was
positive Rich knew he was talking about a west coast manufactured  3CX3000
PA, and not a AL-1500.

3.) Rich's tale about 500 watt 8877 grids. Eimacs own catalog disagrees
and they even have an application note describing how improper tuning can
destroy the grid.

4.) Rich's story about a photon hitting the cathode of a tube ON STANDBY
and blowing up a PA. A physicist who works with that type of stuff every
day said it was bunk.

5.) The story about the variac and filament meter markings **on every
broadcast transmitter** and Rich's slam of every amateur manufacturer for
doing something the commercial manufacturers apparently don't often do.
Several people jumped in and proved he was telling another story.

6.) Measures' claim a certain TL-922 was damaged by a parasitic. The owner
showed up and said "no, it was a lightning arrestor causing the arc, I
removed it and the amp is fine".

7.) Measures' attempt to blame me for Wes' unintentional error. Rich was
completely aware of how this happened BEFORE he posted his pathological
accusation that I was trying to hide something, and that I misled Wes.

When all this is considered it becomes perfectly clear Measures presents
untrue statements as fact, even when he should have known in advance what
he says really isn't true.

We all make occasional mistakes, but this stuff goes far beyond once in a
while. It appears to be chronic or habitual.

73 Tom

 
 
 

Parasitic suppressor data

Post by w8ji.. » Thu, 16 Jan 1997 04:00:00

Quote:>>Extracted from E-mail>>

The suppressor graphs (RL.GIF) seem to show two things:

1. The conventional (non-nichrome) suppressor gives a faster roll-off of
Q with frequency than the nichrome suppressors.

2. There's very little difference between the two grades of nichrome.

You obviously don't want to get publicly embroiled in this controversy,
and neither do I. However, it does seem that the distinguishing feature
of the nichrome suppressors is their low HF Q.  The VHF Qs are all
pretty similar.

The VHF Q of the conventional suppressor could be made exactly the same
as the nichrome ones by changing the value of either L or R, but the HF
Q of the conventional suppressor would still be about a factor 2
higher.<<-<<

I don't blame anyone for avoiding Rich's wrath. But since I am already on
his top ten list, I have nothing much to lose, hi. So I'll post this and
accept the return attack it will almost certainly generate.

This conclusion above is the same conclusion I reached, nichrome
suppressors offer lower HF Q, and nearly identical VHF performance. Just
the slightest adjustment in resistance or inductance of the conventional
copper wire suppressor would result in less VHF Q without greatly changing
HF Q.

If the data is reviewed, the ratio of Q is almost unity at 200 MHz and
over 2:1 at 10 MHz. Just the slightest adjustment of R or L will make the
conventional suppressor equal the nichrome at VHF, while maintaining
better Q at HF where we want losses to be reduced.

For example, the AL-80B oscillates at about 170-180 MHz when the
suppressor is removed. At that frequency, Wes measured a Q of about one
(same as I posted weeks ago). The Q of a duplicate nichrome suppressor is
about .75. This very small Q change is diluted by circuit effects when the
suppressor is installed in an actual PA. The actual operating Q change
would be even less at VHF, and more at HF.

Rich's claim this small change in VHF Q is a great or worthwhile
improvement that cures all woes is completely false. Anyone believing that
would have to have a real problem understanding parallel and series L/R
circuits. Add one turn to the conventional suppressor or adjust the
resistor size, and you've gone even lower with Q than the nichrome.

Finally, I'd like to remind everyone how (over and over again) Measures
squaked about how he could SEE the difference in his dip meter, describing
all the sharp dips that went away when he made (what amounts to) a *very*
small Q reduction at the frequency of interest. Rich would have use
believe he measured a Q change of less than 0.5 with his GDO!

Remember and compare those claims of what he "saw first hand" to other
claims of things he "knew for a fact":

1.) The Miklos employment tale. He claimed he "called Eimac" and they told
him Buzz was never R+D manager. Yet Eimac even issued a letter (after
getting Buzz's permission) explaining Buzz was indeed R+D manager. Not
only that, VHF Handbooks list Buzz as Eimac's former R+D Manager. Even
after the employment confirming letter was out, Rich sent Buzz Miklos a
post card telling Buzz he was never R+D manager!

2.) The tale about Marvin Born. Rich said Marvin measured parasitics in an
AL1500. Turns out it wasn't even an AL1500, it was a dual 8877 PA built on
a old empty prototype chassis. When I talked to Marvin he said he was
positive Rich knew he was talking about a west coast manufactured  3CX3000
PA, and not a AL-1500.

3.) Rich's tale about 500 watt 8877 grids. Eimacs own catalog disagrees
and they even have an application note describing how improper tuning can
destroy the grid.

4.) Rich's story about a photon hitting the cathode of a tube ON STANDBY
and blowing up a PA. A physicist who works with that type of stuff every
day said it was bunk.

5.) The story about the variac and filament meter markings **on every
broadcast transmitter** and Rich's slam of every amateur manufacturer for
doing something the commercial manufacturers apparently don't often do.
Several people jumped in and proved he was telling another story.

6.) Measures' claim a certain TL-922 was damaged by a parasitic. The owner
showed up and said "no, it was a lightning arrestor causing the arc, I
removed it and the amp is fine".

7.) Measures' attempt to blame me for Wes' unintentional error. Rich was
completely aware of how this happened BEFORE he posted his pathological
accusation that I was trying to hide something, and that I misled Wes.

When all this is considered it becomes perfectly clear Measures presents
untrue statements as fact, even when he should have known in advance what
he says really isn't true.

We all make occasional mistakes, but this stuff goes far beyond once in a
while. It appears to be chronic or habitual.

73 Tom

 
 
 

Parasitic suppressor data

Post by Wes Stewa » Thu, 16 Jan 1997 04:00:00



>Subject: Re: Parasitic suppressor data
>Date: 15 Jan 1997 19:14:01 GMT
>>>Extracted from E-mail>>
>The suppressor graphs (RL.GIF) seem to show two things:

The graphs referred to by Tom can now be found on my home page at:

www.azstarnet.com/~n7ws

Wes N7WS

 
 
 

Parasitic suppressor data

Post by R. L. Measure » Fri, 17 Jan 1997 04:00:00


snip...

Quote:> The VHF Q of the conventional suppressor could be made exactly the same
> as the nichrome ones by changing the value of either L or R, but the HF
> Q of the conventional suppressor would still be about a factor 2
> higher.<<-<<

I know who Mr. Rauch is quoting above, but readers, other than Wes, N7WS,
probably do not know.  So far, the person who made this statement has not
come up with a conventional suppressor that will reduce the VHF voltage
gain of an amplifier by the same amount as a nichrome suppressor.  Sure, I
can come up with a suppressor design using a high-Q silver-strap Ls (with
a different amount of inductance) and a different amount of resistance for
Rs, which yields a much lower VHF Q than any of the suppressors Wes
measured for us.   However, such a suppressor creates a 'gotcha'/land mine
that the naysayers don't seem to be aware of yet.  .............Stay tuned
for the next exciting episode.  (Note:  this gotcha is discussed in an
article about VHF suppressors that appeared in the March, 1989 issue of
QST magazine.)

...snip...

Quote:> This conclusion above is the same conclusion I reached, ... snip

What are the values of Rs and Ls that will produce exactly the same VHF Q,
Mr. Rauch?  

...snip...

Quote:> If the data is reviewed, the ratio of Q is almost unity at 200 MHz and
> over 2:1 at 10 MHz. Just the slightest adjustment of R or L will make the
> conventional suppressor equal the nichrome at VHF, while maintaining
> better Q at HF where we want losses to be reduced.

Is a 1% (0.087db) loss at 29MHz going to make a difference at the
receiving end?   Is a 0.25% (0.022db) loss at 14MHz going to make a
difference?  Every benefit has a trade-off.  Is a 1% power increase at
29MHz worth a 2/3, or more,  increase in VHF voltage gain?  

Quote:> For example, the AL-80B oscillates at about 170-180 MHz when the
> suppressor is removed.

However, AL-80s seem to occasionally oscillate at roughly 160MHz with the
factory suppressor installed.  Here's a  clip from an e-mail I recently
received from an AL-80 owner who reportedly  had two bandswitches fail.
  "Hi Rich:  Sorry for the delay but we were out of town.  I am sending
you 2 sets of toasted AL-80A bandswitches.  The first time it arc'ed over
,  I
had no idea what the problem was.  Since I only used it on 75 meters, I
thought it had wimpy bandswitch wafers in it and that was the problem.  I
then soldered the bandswitch in the 75 meter position and of course then
when it  arc'ed it mad more of a mess than the first time.  I had a
chance to put your suppression kit in and what a difference.  You of
course knew this would be the result, but I am most pleasantly surprised.
 The amp tunes up nice and smooth now with no crackling and popping
sounds emanating from inside......."  
 When Rick's 'toasted' AL-80 bandswitches arrive, I will post photographs
of them on the Web for all to see.  .............Once again, Mr. Rauch has
been proved to be correct---i.e., the tune capacitor in the AL-80 has no
resonances around 160MHz that could cause it to arc over from a VHF
parasitic oscillation.  Congrats, Tom.  

Quote:> At that frequency, Wes measured a Q of about one
> (same as I posted weeks ago). The Q of a duplicate nichrome suppressor is
> about .75. This very small Q change is diluted by circuit effects when the
> suppressor is installed in an actual PA. The actual operating Q change
> would be even less at VHF, and more at HF.

Now that we have Wes' measurements, we know that a fairly typical low Q
suppressor has an ESR of 4.32 ohms at 30MHz and an ESR of 0.88 ohms at
10MHz.  Perhaps Mr. Rauch, or another 'recognized amplifier expert' can
show us how to calculate the effect this would have on the Q of the tank
circuit in an AL-80B at 10MHz, and at 30MHz? These calculations are beyond
my capabilities.  

Quote:

> Rich's claim this small change in VHF Q is a great or worthwhile
> improvement that cures all woes is completely false.

Granted, the claims about mirculously curing gout have not been verified
by a double-blind scientific study, but preliminary evidence suggests that
verification is absolutely, positively, 100% certain.  

...snip...

Quote:> 1.) The Miklos employment tale. He claimed he "called Eimac" and they told
> him Buzz was never R+D manager. Yet Eimac even issued a letter (after
> getting Buzz's permission) explaining Buzz was indeed R+D manager. Not
> only that, VHF Handbooks list Buzz as Eimac's former R+D Manager. Even
> after the employment confirming letter was out, Rich sent Buzz Miklos a
> post card telling Buzz he was never R+D manager!

Curiously, Mr. Rauch  does not quote what I wrote.  In the postcard, I
told Mr. Miklos that someone on this newsgroup was providing information
about his prior employment at Varian-Eimac that, according to the
Varian-Eimac's personnel department, did not match his personnel records.

Quote:> 2.) The tale about Marvin Born. Rich said Marvin measured parasitics in an
> AL1500. Turns out it wasn't even an AL1500, it was a dual 8877 PA built on
> a old empty prototype chassis. When I talked to Marvin he said he was
> positive Rich knew he was talking about a west coast manufactured  3CX3000
> PA, and not a AL-1500.

True, it was retrofitted with a second 8877.  As I recall, tank
modifications were made to the AL-1500's tank to double the power handling
ability and halve the input Z in order to match two tubes instead of one.
However, Mr. Rauch's statements are somewhat puzzling.  First Mr. Rauch
tells us it was a 'dual 8877 PA', but then he tells us it was a Create
Electronics Co. 3CX3000A7 amplifier.  
 If Mr. Rauch is correct,  Marvin Born ordered the WRONG suppressor
retrofit-kit.  To explain:  According to my records, Marvin ordered kit
s/n 4548, which was for an AL-1500 with an extra resistor set for a second
8877.  As I recall, Marvin told me that the AL-1500 had no VHF parasitic
suppressors and that he could see intermittent VHF parasitic oscillations
at 87MHz on a Tektronix 454 oscilloscope as well as on a spectrum
analyzer. According to my records, Marvin Born sent a cheque to pay for
suppressor retrofit kit s/n 4548.   However, a suppressor for an AL-1500
would prompty incinerate in a 3CX3000A7 amplifier.  I just telephoned
Marvin to see if a mistake was made.  Unfortunately, no one was home.
I'll try again later.  
...snip...

Quote:> 7.) Measures' attempt to blame me for Wes' unintentional error. Rich was
> completely aware of how this happened BEFORE he posted his pathological
> accusation that I was trying to hide something, and that I misled Wes.

'Unintentional error'?  To the best of my knowledge, Wes did not error
anywhere.  
 RE: hiding something:  Mr. Rauch cancelled his post of 28 November,
sans-explanation.  I believe the reason why Mr. Rauch cancelled this post
has something to do with the belated realization that a small change in
VHF Q affects a large change in VHF Rp.  

Quote:> When all this is considered it becomes perfectly clear Measures presents
> untrue statements as fact, even when he should have known in advance what
> he says really isn't true.

 Mr. Rauch names no such statements.  However,, in his next reply, perhaps
he will take me to to task on the gout issue.  .  

Quote:> We all make occasional mistakes, but this stuff goes far beyond once in a
> while. It appears to be chronic or habitual.

Amen to that, Mr. Rauch.

A question:  An Rs of 100 ohms is connected in parallel with an Ls of
85nH.  Assuming that the intrinsic L in Rs is zero, and the intrinsic R in
Ls is zero, please calculate the currents in Ls and Rs if 1V at 160MHz
when applied.  In your expert opinion, Mr. Rauch, is the resultant current
in Ls insignificant compared to the current in Rs?  

POSTSCRIPT
Did anyone notice that Mr. Rauch avoided the subject of Rp?  When
evaluating suppressor performance, Rp is is an important consideration
because Rp and tube mu determine VHF voltage gain.  Since we can't change
the mu of the tube, Rp is the only game in town for VHF voltage-gain
reduction.  
------------------
e-mail copy to Mr. Rauch

--
--Rich-- ag6k, 805-386-3734

 
 
 

Parasitic suppressor data

Post by R. L. Measure » Sat, 18 Jan 1997 04:00:00



...snip...

Quote:>  Here's a  clip from an e-mail I recently
> received from an AL-80 owner who reportedly  had two bandswitches fail.
>   "Hi Rich:  Sorry for the delay but we were out of town.  I am sending
> you 2 sets of toasted AL-80A bandswitches.  The first time it arc'ed over,
> I had no idea what the problem was.  Since I only used it on 75 meters, I
> thought it had wimpy bandswitch wafers in it and that was the problem.  I
> then soldered the bandswitch in the 75 meter position and of course then
> when it  arc'ed it mad more of a mess than the first time.  I had a
> chance to put your suppression kit in and what a difference.  You of
> course knew this would be the result, but I am most pleasantly surprised.
>  The amp tunes up nice and smooth now with no crackling and popping
> sounds emanating from inside......."  
>  When Rick's 'toasted' AL-80 bandswitches arrive, I will post photographs
> of them on the Web for all to see.  .............Once again, Mr. Rauch has
> been proved to be correct---i.e., the tune capacitor in the AL-80 has no
> resonances around 160MHz that could cause it to arc over from a VHF
> parasitic oscillation.  Congrats, Tom.  

Rick's toasted AL-80 bandswitches arrived today.  I photographed them,
saved the images as JPEG files, and made them available on my Web site at

http://www.vcnet.com/measures/

The images are available at Figures 15a and 15b.  

BTW, replacement AL-80 bandswitches cost $58.22 (inv #02745).

--
--Rich-- ag6k, 805-386-3734

 
 
 

Parasitic suppressor data

Post by R. L. Measure » Sat, 18 Jan 1997 04:00:00



...snip...

Quote:> 2.) The tale about Marvin Born. Rich said Marvin measured parasitics in an
> AL1500. Turns out it wasn't even an AL1500, it was a dual 8877 PA built on
> a old empty prototype chassis. When I talked to Marvin he said he was
> positive Rich knew he was talking about a west coast manufactured  3CX3000
> PA, and not a AL-1500.

I just had a conversation with Marvin Born.  He said the amplifier in
question was built on an AL1200 chassis, had two 8877s, now has one 8877,
and uses a low VHF Q parasitic suppressor intended for an AL-1500.

 Mr. Rauch is correct in stating that Marvin's spectum analyzer detected a
parasitic-oscillation (at 78MHz) in a Create 3CX3000A7 g-g amplifier that
had vapourized various bandswith contacts and destroyed its VHF parasitic
suppressor.  Marvin said he replaced the bandswitch, and replaced the
factory-stock parasitic suppressor with an all-nichrome, resistorless,  low
VHF Q parasitic suppressor.  No further arcing problems have been reported.

Congrats, Tom

--
--Rich-- ag6k, 805-386-3734

 
 
 

Parasitic suppressor data

Post by w8ji.. » Sun, 19 Jan 1997 04:00:00



Quote:>> 2.) The tale about Marvin Born. Rich said Marvin measured parasitics in
an
>> AL1500. Turns out it wasn't even an AL1500, it was a dual 8877 PA built
on
>> a old empty prototype chassis. When I talked to Marvin he said he was
>> positive Rich knew he was talking about a west coast manufactured
3CX3000
>> PA, and not a AL-1500.

>I just had a conversation with Marvin Born.  He said the amplifier in
>question was built on an AL1200 chassis, had two 8877s, now has one 8877,
>and uses a low VHF Q parasitic suppressor intended for an AL-1500.
>Congrats, Tom

It's not just this time Rich, it's nearly all the time. When your stories
are looked at, they almost always wind up being little tiny threads of
fact woven into big fabrications. It's just an attempt to support your
view of how the world works.

When any person repeatedly posts or distributes factoids that are almost
entirely figments of imagination, he looses all credibility. You've done
that over and over again.
Even when you admit being wrong, you still can't control yourself and
"slip in" another false claim!

Look at a small part of your history on this thread:

If Dave had not corrected you in public about the real cause of his
TL-922's arcing (a bad lightning arrestor), you likely would have posted a
picture of the capacitor on your web page and slammed Kenwood even more
than you have for parasitics. You declared the 922 cap damaged from
parasitics, sent Dave a kit, and almost got away with "another one"
except, before installing the kit, Dave found the problem. (By the way,
that was a problem you said could NEVER occur. You plainly said HF signals
or improper loading or antenna termination could NOT cause a PA to arc.)

Just hours after that, WB8BFS came on the thread and said his 922 arced
from a bad relay.

More recently you declared all amateur PA's poorly designed because they
had no rheostats like commercial transmitters, and declared no proper
engineer would purchase a transmitter without one. Several people rebuked
you for saying that, one of whom is a top notch engineer for a large
commercial BC transmitter manufacturer.

Now you've moved on to the AL-80 or something with more Richard L.
Measures picture "evidence". Once in a while you'll find a sucker who buys
into your fantasy, but your days of misleading large numbers of people are
over.

73 Tom

 
 
 

Parasitic suppressor data

Post by Joe Subi » Mon, 20 Jan 1997 04:00:00



writes:
:>
:>
:>Rick's toasted AL-80 bandswitches arrived today.  I photographed them,
:>saved the images as JPEG files, and made them available on my Web site
:>at
:>
:>http://www.vcnet.com/measures/
:>
:>The images are available at Figures 15a and 15b.  
:>

The pictures are interesting and prove nothing.

The arcing visible in the pictures could just as easily been caused
by a mistuned amplifier running into a high VSWR.  I'm sure someone
will correct me if I get it backward but in and underloaded amplifier
driving a high impedence load the voltage across the bandswitch (and
tuning capacitor) will soar nearly out of control.  Underloading and
high feedline impedences are particularly common on 80 and 160 meters
as many amplifiers lack sufficient range in their output capacitors to
achieve proper loading ... particularly if the load impedence is very
capacitive.  

Rule #1 ... if one hears hoofbeats don't expect zebras.

--
========================================================================
Joe Subich, W8IK ex-AD8I                        




========================================================================