See below;
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
On Oct 22, 2006, at 7:39 AM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
his Ameritron/ Heath/ Dentron /Amp supply/ MFJ 'engineering'
MFJ has a rather well deserved reputation as the junkiest
commercially built Hamstuff on this planet. I have heard
numerous
Hams refer to it as Mother F___ing Junk. Also, as I understand
it,
an MFJ "3000w" antenna tuner was the only one ever tested in the
ARRL
Lab to ignite at 900W.
#### any idiot knows you can't use Delrin rod as a form for a
roller inductor..
Oren Elliot mfg the roller inductor.
Oren Elliott changed the design of the coil form using another
material after this happened. I remember e-mailing Steve Elliott
about this and he mentioned them changing it. When they designed the
coil, they didn't check it at RF frequencies. Evidently, they didn't
have anything there to test at high power with at the time, if I
remember the conversation correctly. Anyhow, they're safe for use now.
The problem here sounds to me like MFJ continued selling the tuners
with the delrin form inductors after knowing them to be bad. It also
says the MFJ must have NEVER tested the tuner under full power before
they started building them! Any good manufacturer would have delayed
the sales and shipment until new replacement inductors could be
installed. It sounds to me like they sent them out hoping some would
make it. The ones that didn't, simply send a new inductor and get out
of the labor. That is unless it failed under warranty and they had to
do the labor. It still sounds an awful lot like a bunch of penny
penching happened.
.. and even if you didn't.... when u went to test
it for the 1st time... "in the lab".... it would melt in front
of
yours eyes ! They shoulda simply tested the prototype under
worst case condx... 1st.
900w into a "3000w" tuner is hardly a worst case, Jim.
Every one of em went back too. ..
well, a few didn't.... talked to a fellow 3 weeks ago.. who just
literally melted his one hr b4.
One of the best laughers I heard from Tom was his assertion
that
MHJ/Ameritron amps don't have a glitch-resistor because the
filter
caps they buy have so much ESR built right in that they can't
produce
enough peak current to damage a tube.
### I saw that too. Rauch figured 1 ohm per cap + 2 ohms
for
the plate choke = 10 ohms.... hence no glitch R required.
Like KM1H said.... "a lot of water has passed under the bridge
since ur days at heathkit, Tom" My new 2500 uf @ 450V caps
are 50 Miliohm ESR.... EACH ! Plus a 10 A CCS ripple
current
rating [ @120 hz.... less at 360 hz]
### How ANY amp manufacturer can be SO cheap, as to exclude
the
Glitch R these days..... is just a cost cutting tight wad... out
to
enhance profits. If they went cheap there... ask
urself... "where else did they cut corners". Ain't no corners
left to cut on any Ameritron product..... they have all been
chopped
out.
Even the CB amp builders that made the better built amps used glitch
resistors. One would think that if they would use them, an amateur
radio manufacturer would surely spend the money to use them. When you
buy a large quantity like they would have, the cost drops a good bit.
or
(d) doesn't like the idea that he will never post here,
I hope he does post here. If Tom is not allowed to post here, I'm
outta here.
### He will be allowed to post here... nobody is stopping him...
[except W8JI]. This is an uncensored forum remember ? My
guess
is, without his.... 'groupies' to come here with him.... we
will
all pounce on him... and eat his lunch !
I will say nothing at all unless he drops the ball.
He wouldn't last 10
minutes here... or any other uncensored group.
My guess is that he could if he could ever park his Hubrismobile.
and
can't do his own rebuttal (e) can't defend the superb
engineering of Ameritron products.... like the AL-1500's 8 x
lytics being run at their MAX + voltage ratings... then
saying "that's ok" .... "just make sure the bleeder eq
resistor's don't ever open up, or the lytics WILL start
blowing
up en masse" [If u ran the lytics at the prescribed 75%
max V rating the manufacturer's recomend, they will NOT blow
up, if
the bleeder EQ resistor's open up.]
I'll bet a medium pizza with 5 toppings that I can show an
example where a 75% safety factor would cause a serious problem
if
a bleeder- R opened.
### U may well be correct
There goes the pizza.
IF the caps were badly mismatched in
UF to start with.
Not even with 1% matched.
Now you would think Ameritron would buy em
10,000 at a time... in 5-10% Tol... then pay some new employee
min wage to play.... "match up the caps in groups of 8".
Heck, I
believe Harbach matched up all his caps b4 shipping
In the last batch of 104 Matsushita/Panasonic, 105?C, 560uF, 450v,
35mm x 51mm low ESR caps we stocked, the cap-to-cap variation was
under +/¨C 4%. Shocking!
.
### also.. My idea of adding a 2nd 100K resistor across each
cap
is flawed.
Agreed. We have sold over 12k Matsushita, 3W, 100k-ohm MOF
resistors, so far there have been zero reported failures, and ther
is
typically <0.3% variation in measured R in the same 1000-unit
box. .
If just one of the PAIR of resistors opened up.. the
V would skyrocket on that cap... regardless of the number of
caps
in the string.
If there were two R-equalized caps in the string, V would
eventually
double where one R opened.
In fact... that one cap would have DOUBLE the V
of the remaining intact caps/resistor's.
With 8 caps, opening one equalizer -R would eventually increase
the
voltage at the open R's cap by 8x.
IMO.. 1 x resistor per
cap... that's it. THEN, if any resistor let go... V would
divide according to each caps UF... with the caps with the
highest
UF getting the most V.
Eventually there would be 0v on all the caps with intact equalizer/
bleeder resistors and 100% of the voltage on the cap with the open
R. Of course the potential would never get there since
electrolytics
tend to go BANG with not much of a surge in voltage.
### we all know who the secret administrator is now.... it's
Joe Subich W4TV.... blatantly obvious now.
Not a sound wager. The only thing we know for sure is that Tom
is
the first to provide the reasons (excuses) why someone got his
posterior jackbooted off of AMPS, and that anyone there who
questions
Tom's technically questionable statements is stepping into deep
feces.
### Partially agreed. There is absolutely NO reason for the
administrator's identity to be kept secret.... unless he's W8JI
in disguise.... which would
* Did *
make a mockery of the 'amp'
reflector. What's this secret administrator worried about...
Being fingered as a guy who can't stand to have his stuff
scrutinized.
threats, lynching's ? Perhaps he was 'appointed' by the CIA..
or maybe Riley H himself ?
When he phoned me about retrofitting his 922, I found Riley
Hollingsworth to be a rather pleasant guy to converse with.
Who ever he is... he's a hypocrite.
He provides no callsign yet he jackboots participants who don't
provide him with their callsign. Guffaw.
R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org
Best,
Will
