[TenTec] Power supply for Hercules II

[Jim Brown]

I don't see the need to change the power connector. If the cable from 
the power supply is split to all of the pins on the stock power 
connector, it's current rating is quite sufficient.

I DO agree with using short, fat copper between the supply and the amp. 
There ARE industrial grade SMPS units that are good enough, but they can 
be hard to identify, and even the best are likely to require RFI 
suppression in the form of serious common chokes on both the AC and DC 
side. Use guidelines in the Choke Cookbook in k9yc.com/RFI-Ham.pdf.

As to the super capacitors -- if large enough to support the load, a 
super cap can reduce the IR drop in the DC wiring between PSU and rig. 
This can be a big deal if you're running SSB and powering audio 
interfaces from the same PSU as the rig or power amp. The IR drop in the 
green causes the voltage between the rig, the PSU, and the audio 
accessory to be modulated by the envelope of the modulation, which can 
couple into the audio and sound like RF feedback. At the 100W level, 
I've measured several hundred mV between PSU chassis and rig chassis.

73, Jim K9YC

On Wed,5/10/2017 10:24 AM, Fernando wrote:
> Oh.. as an aside.
>
> I’m pondering this Herc mod:
>
> <http://www.nx7u.net/Hercules.html <http://www.nx7u.net/Hercules.html>>
>
>
> Fernando N2FQ/6
> n2fq at sbcglobal.net <mailto:n2fq at sbcglobal.net>
>
>
>
>
>> On May 10, 2017, at 10:06 AM, Katz Ajamas <ajamas.rn at gmail.com <mailto:ajamas.rn at gmail.com>> wrote:
>>
>> I am using a battery at present. It works well but but I do not charge
>> indoors and with an expectation of increased operating time, charging is
>> going to be a hassle. Also, once past 20% discharge, it's no better than
>> the SMPS I have.
>>
>> The 2SC2879 transistors are supposed to run at 12.5V for best intermod
>> specs. The HP SMPS supply I have now barely makes 12.3V. There is a good
>> bit of drop in the stock Tentec cable and some more with the inner
>> connections.. The connector appears to be rated for the current. Bottom
>> line, the devices are running at about 11.6V for 500W output.
>>
>> I'd like to find a matching Tentec supply for a reasonable (caps likely
>> need to be replaced) price.
>>
>> Looking around at other options, there is a "Meanwell" brand SMPS at Mouser
>> and Arrow that makes 13.5V-16V adjustable, has voltage sense lines that can
>> be wired to the collectors, and can be turned on and off with a TTL signal.
>> It is class B EMI rated.
>>
>> In trying to get a handle on the class B spec, I find a radio station on
>> 1.5MHz and has a 400uV/m contour at my location is S7. Alas, the class B
>> spec is for a conducted "limit" and does not make sense at 250uV as this
>> will be very sensitive to the impedance of the 'antenna'. Is this the
>> common mode PtoP that is acceptable at the power leads? In OR out?
>>
>>
>> The supply is $259 with free shipping from Arrow. Same price from Mouser
>> but plus shipping. $219 plus $30 shipping from HongKong seller. Mouser
>> looks like the best bet because they have a 30 day return policy. Unless,
>> someone who has used one of these can tell me about EMI and also about
>> whether it is reasonable to turn the supply and Hercules on during transmit
>> and off during receive. I'm not talking QSK rates. Just between exchanges.
>>
>> What say?
>>
>> 73, -Bob
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -- 
>> -do not look into LASER with remaining eye!
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