[Amps] ACOM 1500 1ATR4B errors
Larry Williamson
larry at mygbi.com
Tue Nov 13 12:17:20 EST 2018
Bruce,
I would have contacted Val directly @ val at acom-bg.com first. If fact, Val would prefer to work directly with you so possibly save the cost and headache of sending it in.
If you have not sent it in yet please shoot Val an email and he will respond within the same day. Val will work right with you as you both determine the cause and possible fix.
A new board will probably be sent and it only take about 3 days to ship it.
Pictures and video are your friend here--- Follow his instructions to the note and you'll be up and running before you know it!
Cheers
Larry
N7ZDR
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Subject: Amps Digest, Vol 191, Issue 11
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Today's Topics:
1. ACOM 1500 1ATR4B errors (wa3afs at nycap.rr.com)
2. Re: Alpha front panel overlay (Martin Sole)
3. Re: Choke anomoly (Jim Garland)
4. Choke anomoly (Jim Thomson)
5. Choke anomoly (Jim Thomson)
----------------------------------------------------------------------
Message: 1
Date: Mon, 12 Nov 2018 13:48:11 -0500
From: wa3afs at nycap.rr.com
To: amps at contesting.com
Subject: [Amps] ACOM 1500 1ATR4B errors
Message-ID: <5BE9CAEB.1179.1BCF712 at wa3afs.nycap.rr.com>
Content-Type: text/plain; charset=US-ASCII
My two and half year old ACOM 1500 started dropping back to standby mode with the 1ATR4B error (related to the vacumn tr relay) which became more and more often.
I have placed the amp into an envelope (large) and it is now waiting for repair at HRO in Virginia.
I have been driving the amp with the ICOM 7610 (delay default at 10ms, no buffer interface) for the past 11 months (before that was the ICOM 7600) and have the PALSTAR HF-AUTO tuner following the amp.
My question for when I receive the repaired amp back is there anything (settings, etc) that would lessen my chances of this happening again?
I generally run the ACOM 1500 at 900 watts or less (learned my lesson by blowing up a capacitor in the LDG-1000 Pro and killing an Ameritron remote antenna switch) . 160m through 6m SSB, CW, FT8, RTTY)
73
Bruce, WA3AFS
AEC, Albany County
ASEC, Eastern NY
SKYWARN Regional Coordinator, NWS, Albany, NY
Net Manager, ENY ARES/RACES Section Net
------------------------------
Message: 2
Date: Tue, 13 Nov 2018 07:05:47 +0700
From: Martin Sole <hs0zed at gmail.com>
To: amps at contesting.com
Subject: Re: [Amps] Alpha front panel overlay
Message-ID: <37a0bc92-3b56-4f61-14d4-fc5e2e8a32a0 at gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
I have never seen an overlay for an Alpha amplifier. I have seen them for Heathkit amplifiers but never seen one advertised for an Alpha.
Given the general value/cost of Alpha amplifiers I'm not sure there would be much market for such, especially given that as you have seen there seem to be a number of complete panels available from time to time.
Have you tried contacting one of the people doing full panels? Maybe it would be a much more affordable prospect if they take your old panel in exchange.
Martin, HS0ZED
On 09/11/2018 22:38, Danny Pease wrote:
> I have seen reproduction front panels for some of the older Alpha
> amplifiers, has anyone made an overlay for the 76 series? This looks
> like a simpler and cheaper option for those amps with the sticky paint
> or any that simply need a freshening up.
>
> NG9R
>
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------------------------------
Message: 3
Date: Mon, 12 Nov 2018 17:27:22 -0700
From: Jim Garland <4cx250b at miamioh.edu>
To: amps at contesting.com
Subject: Re: [Amps] Choke anomoly
Message-ID: <20a73358-df34-b9db-cd86-c08e8e4de438 at miamioh.edu>
Content-Type: text/plain; charset=utf-8; format=flowed
Hmm, I wouldn't have said exactly that a choke is a constant current device, but I get where Bill is headed. Choke input filters resist changes in current because the choke inductance L induces a back EMF (induced voltage) in response to any change in current. This induced voltage tends to resist the change.
By contrast a big filter capacitor maintains the voltage, even as the load changes. It does this because when the load decreases, the capacitor dumps charge into the load to maintain the voltage. That's why the voltage that backs up your computer memory can be maintained either by a backup battery or a whomping big (e.g.,1F) capacitor.
There's a tendency with capacitor banks in power amplifiers to suppose that more is better, for example that a 200uF filter is more desirable than a 20uF filter. There are two schools of thought on this subject.
One is that the large filter cap will stabilize power supply voltage better than the 20uF filter, and that is undeniably true. However, the other school maintains that a smaller capacitor will result in a CW signal which "thumps" slightly, as the power drops on each dot or dash.
Some folks like that sound, and I have to admit I kind of like it, too, though I am sure purists will disagree.
Also, with large capacitors, there are the issues of safety and the risk of damage from high surge currents. The stored charge in big capacitor bank can store a ton of energy, and unless the amp is designed to handle it (e.g.,with a carefully engineered step-start circuit) the result can be serious amplifier damage ?73, Jim W8ZR
On 11/10/2018 4:35 PM, Bill Turner wrote:
> ------------ ORIGINAL MESSAGE ------------(may be snipped)
>
> On Thu, 8 Nov 2018 21:43:02 -0800, you wrote:
>
>> Any comments would be greatly appreciated.
>>
>> Jim VE7RF
> REPLY:
>
> You don't need a choke at all, at least for SSB or CW. A choke is a
> constant-current device, exactly wrong for SSB and CW. Just bypass it
> and be sure you have at least 35 uF of capacitance. Your SSB or CW
> amps needs a constant voltage source, not constant current.
>
> 73, Bill W6WRT
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------------------------------
Message: 4
Date: Mon, 12 Nov 2018 20:03:11 -0800
From: "Jim Thomson" <jim.thom at telus.net>
To: <amps at contesting.com>
Subject: [Amps] Choke anomoly
Message-ID: <50CD042C91174C739F24009333A4CAAE at DESKTOPSV54DBH>
Content-Type: text/plain; charset="UTF-8"
From: Bill Turner <dezrat at outlook.com>
To: Amps group <amps at contesting.com>
Subject: Re: [Amps] Choke anomoly
>Any comments would be greatly appreciated.
>
>Jim VE7RF
<REPLY
<You don't need a choke at all, at least for SSB or CW. A choke is a <constant-current device, exactly wrong for SSB and CW. Just bypass it <and be sure you have at least 35 uF of capacitance. Your SSB or CW <amps needs a constant voltage source, not constant current.
<73, Bill W6WRT
## Bill this is for a C ? L ? C filter. The software depicts superb dynamic
regulation, with or without the choke. The addition of the choke just kills the
ripple to an extreme low value. I can shunt the choke with a spst 25 kv ceramic vac relay. Then it becomes a C-C network... IOW 2 x filter caps
in parallel. I used the stepped load feature of PSUD..and toggled between
normal idle current..and full bore plate current ( asap, instantaneous load switch),
then compared the C ? L ? C vs the C-C.
## heres what does not work, a C-L or C-C-L. In those cases, the choke
provides zero ripple reduction, none.
## What else that does work is a C-R-C filter. Not as good as a choke, but extremely
effective. Again, what does not work is a C-R or C-C-R filter, no improvement in ripple.
Jim VE7RF
------------------------------
Message: 5
Date: Mon, 12 Nov 2018 20:52:41 -0800
From: "Jim Thomson" <jim.thom at telus.net>
To: <amps at contesting.com>
Subject: [Amps] Choke anomoly
Message-ID: <13E99296BF144888AA7D6D019BB5C35B at DESKTOPSV54DBH>
Content-Type: text/plain; charset="iso-8859-1"
Date: Sun, 11 Nov 2018 17:49:09 +0000
From: Manfred Mornhinweg <manfred at ludens.cl>
To: amps at contesting.com
Subject: Re: [Amps] Choke anomoly
<Jim,
> I measured the DC resistance, using my fluke 87..and it measured
> exactly 10.0 ohms. Then re-measured using my B+K 875-A... and
> it spits out 8.7 ohms.
Such a big choke can easily fool a multimeter, due to the high inductance and low resistance. If the multimeter uses anything other than a constant, regulated DC for measuring resistance, the inductance will affect the reading and make it useless.
## Not quite useless. The B+K jived with the indicated vdc / current
as displayed on the lab supply.... b4 I blew it up.
## What I was told by engineers at hammond..who own the Dahl xfmr and choke line is.... the choke requires DC bias to measure its inductance. With the
correct test gear used, the choke is actually 4H..with 3A flowing through it. But the
2 pieces of test gear they use is beyond cost prohibitive for typ hams.
https://url.emailprotection.link/?aZU8A07Q9yJJ3dTbYk0gD113e0EN4b78lv8G5B5QQHAs4RdqCdDmYqFdQ3ah1_9dec32fl8c6A5flhCMh-9COMQ~~ inductance meter
https://url.emailprotection.link/?aZU8A07Q9yJJ3dTbYk0gD113e0EN4b78lv8G5B5QQHAs4RdqCdDmYqFdQ3ah1_9dew3SmNvPB0TlPFqdTUXGO-A~~ mating 25 A / 125A bias units.
Then I noticed the 4 x 5 x 12 small lab supply leaned over... and
> STUCK to the left side of the choke! The dahl choke uses the same
> pair of hypersil C cores as their 10 kva CCS plate xfmrs,
> identical, except the choke, of course has just a single winding. I
> had a 8 inch long, chrome plated letter opener close by, and it stuck
> to the left side of the choke, like a magnet. Heres the kicker,
> the same metal letter opener, would NOT stick at all when placed on
> the RIGHT side of choke. Choke is 13 inches wide x 8 inches
> deep, x 11 inches tall.
<I understand this is a double-U core made from wound tape. So it has just two magnetic joints, rather than the three of a doble E or an E-I core. Either one or both of those magnetic joints must have a gap in between. ALthough called airgap, it's normally filled with some non-magnetic spacer, rather than air. Try to see if your core is gapped just on one side. If so, then of course that side will attract objects, and the other side will not, or at least much weaker.
### Problem solved, You are correct of course, there is a insulated gap on BOTH U shaped cores, aprx 1/4 the way down from the top.
Like an idiot, I knew abt the gaps, but did not realize I had placed the
blade of the letter opener way too low on right side core. Once aligned on the
gap, it sticks like concrete, mother of all magnets. Identical on both sides.
## I obtained another lab supply to continue the testing above... but lab supply #2
is just a 0-37 vdc @ 3A type. The blown up one is fixable. I got smart this time,
and installed paralleled 6A10 diodes across the choke to kill any back EMF. Zero issues
with current limit control, or voltage adjust.
## I ran 3A CCS through the choke for 2.5 hrs straight. ZERO heat at all from the windings
for the 1st hr. Barely luke warm after 2.5 hrs. DC resistance had risen from 9.7 ohms cold,
to 10.62 ohms after 2.5 hrs. Inductance rose slightly from 3.68 to 3.74 H.
## with the blown up supply, I could have stuffed a lot more current that 3A through the choke..
and probably could get it hot... like 50-60 volts at 5A. You increase current so much, then it goes into thermal runaway,
and stuff heats up very quickly. At least thats my experience with plate chokes. IE: 1.5A,
the plate choke runs at room ambient temp, then gets toasty warm at 1.6A..and hot at 1.7 A...
and blazing hot to touch at 1.8A.
<RIP, poor little power supply... :-)
## Its an expensive...poor little power supply, that requires fixing asap.
> Using the PSUD software, the C-L-C config has merit, for reducing
> ripple down to extreme low values. Interestingly enough, a C-R-C,
> using a simulated 8.7 ohm resistor, also works very good, not as
> good as a choke, but extremely effective. The C-R-C config would
> reduce ripple by a factor of 10. And thats with the same dcV drop
> across the 8.7 ohm resistor as the 8.7 ohms across the choke. The
> C-L-C config would provide for a ripple reduction with a factor of
> 550.
<Nice - but a modern switching power supply would reduce the ripple much more, give you a highly regulated voltage even while the line voltage varies by 30% or more, and as a bonus give you almost perfect power factor - all while being about 50 times lighter.
And of course, about 200 times more complex, too... ;-) Nothing comes free in this life...
<Manfred
## 40 Millivolts P-P with 7 kv under a load of 3 A is superb in my book, thats like .00057 % RMS ripple. However, I cant do anything about the lousy
power factor.... nor the incoming line voltage variations when loaded. You are
correct though, its all stupid heavy, bulky etc.
## One drawback I see on all switching supplies is they cant be operated at more than
a tiny bit above their rated current. IE 20A CCS switcher, typ good for 22A ICAS. No big issue
just use a bigger switcher.
## I did notice that continental electronics in Dallas Texas, who builds SW BC TX, uses
a string of series connected switchers for their B+ supply. Typ they would total 11-12 kv in the steady
state, with an Un modulated cxr... and double to 22-24 kv, when modulated 100% on AM... and even
more with 125% modulation used. Then down to zero volts, when modulated 100% negative. I Think
each switcher was aprx 700 vdc in the idle condition...and rising to 1400+ VDC on positive mod peaks.
Typ 17 used. So high B+ levels can be done with series switchers.
## For now, Im just using what I have readily available. Xfmrs, chokes, HV lytics, 6A10 diodes,
metal and glass tubes, manual tuned Pi nets, surplus vac tune and load caps, vac relays... copper tubing
from home depot, aisle three, all old school stuff.
Later... Jim VE7RF
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