[Elecraft] RX antenna & carrier-operated relay

[Jim Brown]

Fabio,

You've seen my antenna farm -- Beverages run within 20-30 ft of my 160M 
TX antenna facing NE. Beverages feed a DX Eng preamp before going the 
sub-RX. I don't do anything special to protect the radio, but it does 
occasionally protect itself. I also use the Beverages on 80, 40, and 
30M, but TX antennas are much farther away (more than 100 ft). This is 
at 1.5 kW with a Ten Tec tube amp.

BTW -- I just added a pair of VE3DO loops tuned for 160M and aimed to 
EU.  Each loop is a rectangle 40 ft long and 10 ft vertical, with the 
bottom wire 2 ft off the ground and fed at the center. Details on 
OK1RR's website. The two loops are spaced 5/8 wavelength (350 ft). You 
probably don't have room for two loops, but you might fit one of them.

73, Jim K9YC

On Sat,3/4/2017 2:11 PM, Fabio IZ4AFW / NZ1W wrote:
> Hi Dave,
>     thanks for the suggestion.
> I tried doing a quick measure using a cross-needle SWR meter today,
> using the lowest setting.
> On 40m the power appears to just deflect the needle, well below the 0.5W
> mark. Probably I could say less than 250mW, maybe 100mW.
> I usually have an external relay in a box to disconnect the RX antennas
> while transmitting, but not today.
> I was thinking why the RX antennas remain connected when transmitting if
> there's not another use in a typical single-op station.
>
> Thanks,
> Ciao
> Fabio
>   IZ4AFW / IO4W / NZ1W
>
>
> Il 04.03.2017 13:12, David Olean ha scritto:
>> Hello Fabio
>>
>>      I have two beverages  that are somewhat close to my TX antenna. One
>> had about 75 mw on it during TX while beverage #2 had about 1 watt! This
>> is enough power to cause damage to preamps, so I made two power limiters
>> and now the inputs are clipped at about 0 dBm. All it took was two
>> transformers and two diodes in a box. Do you know what the power level
>> is on your beverage during transmit periods?  Really high power levels
>> could burn up the transformers.  Disconnecting the antenna is a good
>> idea too.
>>
>> Dave K1WHS
>>
>>
>> On 3/4/2017 9:53 AM, Fabio IZ4AFW / NZ1W wrote:
>>> Hi guys,
>>>      I was thinking of a possible firmware improvement related to the
>>> carrier operated relay.
>>> I use my radio on a small lot and recently I added a short beverage
>>> antenna for low-bands receiving. My main activity is single-op
>>> contesting.
>>> Because of the interaction between the tx antennas and the beverage, on
>>> some bands I have the COR (carrier operated relay) activating when I use
>>> high power.
>>> I know the good solutions, but my point is different.
>>> As I have the COR activating only when the RX Ant input is selected, why
>>> doesn't the K3 firmware disable it when pushing the ptt?
>>>
>>> In fact, when I push the ptt I don't need the RX-ant part to be active,
>>> as I'm transmitting, and -at least in my setup- I have no other
>>> rigs/devices that need that input (I mean, no in-band receivers and so
>>> on).
>>> Instead of using external relays (ptt-activated) that cut out the rx
>>> input when I am transmitting, why the K3 firmware just doesn't disable
>>> the RX ant input on its own (and re-enables it if needed when releasing
>>> the ptt)?
>>> Maybe I'm missing something here, or that could be a nice improvement
>>> for a next firmware release.
>>>
>>> Thanks for any comment,
>>> Ciao 73
>>>    Fabio
>>>    IZ4AFW / IO4W / NZ1W