[MRCA] [armyradios] RE: AB-1241 - DC current rating?

[J. Forster]

There are two typed of DC blocks...  One has a capacitor in the center
conductor only; the other in both the center and shield. You want the
former.

Look at the spec sheet for the block. You want the capacitor's impedance
to be <<50 Ohms at your lowest operating frequency. This easy enough at
microwave frequencies, but more of a challenge at HF.

-John

================



> Yes that is a good suggestion. Would a series cap do the trick (isn't that
> whats in a dc block?) And if so, what effect would that have on antenna
> impedance and tuning it out?
> Thanks
>
>
>
> 73 Eugene W2HX
>
>
> -----Original Message-----
> From: D. Platt [mailto:jeepp at comcast.net]
> Sent: Wednesday, April 25, 2012 12:27 PM
> To: W2HX
> Cc: 'armyradios at yahoogroups.com'; mrca at mailman.qth.net
> Subject: Re: [MRCA] AB-1241 - DC current rating?
>
> I don't think you want to present DC to a virtual short, in any case,
> whether or not the transformer or the radio could accept/stand it..  Why
> not simply add a coaxial DC block to the transmission line and eliminate
> the issue, altogether.  Just a suggestion...
>
> de Jeep - K3HVG
>
> On 4/25/2012 12:01 PM, W2HX wrote:
>> Hi there. I am referring to the "hubcap" stand often used with the
>> AS-2259/GR NVIS antenna.  This base has a dc resistance of zero because
>> of a transformer within it.  I am looking to use this with a radio that
>> has a DC voltage on the antenna BNC, but current limited to about 30ma.
>> Anyone have an opinion whether a constant 30ma DC current on this
>> transformer would be tolerated by the transformer in the base?
>>
>> http://www.prc68.com/I/Images/AB1241_PRC104.jpg
>> (image courtesy Brooke N6GCE)
>>
>>
>> 73 Eugene W2HX
>>
>> ______________________________________________________________
>>
>
>
>