[Elecraft] Issue 12 re Astron Power Supply

Tue Apr 17 23:36:12 EDT 2018

Well, well. The meter on the front of the Astron 35 says 14.5 volts.  My 
DVM across the output says 13.5. No wonder my front panel reads 13.3 in 
receive mode.

Looks like a calibration is in order.  I didn't realize they could get 
"off."  Instructions available on the Internet.  You can adjust both the 
output and the meter.

k4ia, Buck
K3# 101
Honor Roll  8B DXCC
EasyWayHamBooks.com

On 4/17/2018 2:45 PM, David Box wrote:
> Like all of the "12VDC"  rigs made today the IMD on the K3 is sensitive 
> to input voltage.  I would recommend you get the input up into the 
> 14.8VDC range as it will reduce the IMD products.  I have mine such that 
> on CW key down 100W the internal K3s voltmeter reads 14.5VDC which is 
> basically the reverse protection diode drop from the 14.8VDC input.  I 
> am using a TGElectronics battery booster with about 4 in cable from the 
> battery booster to the K3s.
> 
> Dave K5MWR
> 
> 
> 
> On 4/17/2018 1:36 PM, Buck wrote:
>> What is the minimum recommended voltage for the K3S?  Using the stock 
>> Elecraft 5' cable, I drop from 13.3 to 12.7 volts on key down.
>>
>> Buck, k4ia
>> Honor Roll
>> 8BDXCC
>> EasyWayHamBooks.com
>>
>> On 4/16/2018 4:51 PM, Joe Subich, W4TV wrote:
>>> On 2018-04-16 4:26 PM, hawley, charles j jr wrote:
>>>> So 4 sets of power pole connectors plus 2 fuses.
>>>
>>> Even if the power pole connectors are assembled perfectly and
>>> mated with optimum tension, the resistance in just the four
>>> (15 A) power pole connectors in the negative lead is equivalent
>>> to nearly 40 feet of #12 copper wire!
>>>
>>>> The voltage at the rig, K3, now drops a volt when putting out 100
>>>> Watts.
>>>
>>> With the equivalent of 50 feet of power cable (4 connectors plus a
>>> 10 foot physical cable), I would not be surprised.  Assuming 20A
>>> in transmit (on 15A power poles!), a 1V drop represents 0.05 Ohms
>>> of total circuit losses .... that's pretty good for 10 feet (x2)
>>> of cable plus eight connectors (4 in the + lead, 4 in the - lead)
>>> and the switching device (probably a Schotkey diode).  However,
>>> the 0.05 Ohms in the negative lead is probably ten times higher
>>> than in a braided bonding connection directly from the K3 chassis
>>> to the power supply chassis.
>>>
>>> I'm surprised that only 75% went through the ground path - that
>>> indicates the ground path has 1/3 as much resistance as the "right"
>>> (V- lead) path.
>>>
>>> 73,
>>>
>>>     ... Joe, W4TV
>>>
>>>
>>> On 2018-04-16 4:26 PM, hawley, charles j jr wrote:
>>>> About 75% went thru the ground path. The 10 ga to the rig went from 
>>>> Astron to a battery switching device in case of power outage, to rig 
>>>> runner and to rig. So 4 sets of power pole connectors plus 2 fuses. 
>>>> I’m thinking of changing some of that too. The voltage at the rig, 
>>>> K3, now drops a volt when putting out 100 Watts.
>>>>
>>>> Chuck Jack
>>>> KE9UW
>>>>
>>>> Sent from my iPhone, cjack
>>>>
>>>>> On Apr 16, 2018, at 3:14 PM, Wes Stewart <wes_n7ws at triconet.org> 
>>>>> wrote:
>>>>>
>>>>> I would hope that "much of the current..." wasn't really much.  The 
>>>>> direct conductor from the negative terminal of the power supply to 
>>>>> the radio should carry the majority of the supply current,
>>>>>
>>>>> Wes  N7WS
>>>>>
>>>>>>   On 4/15/2018 7:38 PM, hawley, charles j jr wrote:
>>>>>> This thread prompted me to check out my Astron vs35m. It had a 
>>>>>> small black wire from -V connected to the bottom of the chassis. 
>>>>>> Perhaps it could be called a case or cabinet...more importantly, 
>>>>>> it’s what the green wire from the line cord is connected to. I 
>>>>>> disconnected the black wire. When it was connected, much of the 
>>>>>> current that would have passed thru the negative power wire from 
>>>>>> the power supply to the rig was shunted thru the green power cord 
>>>>>> wire, the ground buss bar, and other ground connections.
>>>>>>
>>>>>> Chuck Jack
>>>>>> KE9UW
>>>>>>
>>>>>
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