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Re: [Amps] ACOM 1500 1ATR4B errors

To: "" <>
Subject: Re: [Amps] ACOM 1500 1ATR4B errors
From: Larry Williamson <>
Date: Tue, 13 Nov 2018 17:17:20 +0000
List-post: <>

I would have contacted Val directly @ 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! 

-----Original Message-----
From: Amps [] On Behalf Of
Sent: Tuesday, November 13, 2018 10:00 AM
Subject: Amps Digest, Vol 191, Issue 11

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Contents of Amps digest..."

Today's Topics:

   1. ACOM 1500 1ATR4B errors (
   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
Subject: [Amps] ACOM 1500 1ATR4B errors
Message-ID: <>
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 
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)
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 <>
Subject: Re: [Amps] Alpha front panel overlay
Message-ID: <>
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
> _______________________________________________
> Amps mailing list


Message: 3
Date: Mon, 12 Nov 2018 17:27:22 -0700
From: Jim Garland <>
Subject: Re: [Amps] Choke anomoly
Message-ID: <>
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
> 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
> _______________________________________________
> Amps mailing list


Message: 4
Date: Mon, 12 Nov 2018 20:03:11 -0800
From: "Jim Thomson" <>
To: <>
Subject: [Amps] Choke anomoly
Message-ID: <50CD042C91174C739F24009333A4CAAE@DESKTOPSV54DBH>
Content-Type: text/plain;       charset="UTF-8"

From: Bill Turner <>
To: Amps group <>
Subject: Re: [Amps] Choke anomoly

>Any comments  would be greatly appreciated.  
>Jim  VE7RF


<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   
regulation, with or without the choke.   The addition of the choke just kills 
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 
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" <>
To: <>
Subject: [Amps] Choke anomoly
Message-ID: <13E99296BF144888AA7D6D019BB5C35B@DESKTOPSV54DBH>
Content-Type: text/plain;       charset="iso-8859-1"

Date: Sun, 11 Nov 2018 17:49:09 +0000
From: Manfred Mornhinweg <>
Subject: Re: [Amps] Choke anomoly


> 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.
  inductance meter
  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...


##  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 
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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