Topband: Two wire beverage question

[Herb Schoenbohm]

Ken,

I would avoid any attempts to do relay switching by supplying voltage 
down a coax cable but rather use two coax runs.  The relay, blocking 
cap, diode and associated circuit in my case with two DXE boxes have 
deteriorate within less than a year to be useless, mostly due to 
electrolysis and zillions of ants attracted apparantly by the voltage or 
relay coil vibration when pulled in. (Yes I covered all the edges with 
silicon sealant)   DXE refuses to send me a print to repair the board 
for what reason I don't know, thus  making repair very difficult.   They 
worked well when I got them but are useless today.    Another 
disadvantage of having a blocking cap in the signal line is that you can 
not determine the coax run continuity through the windings of toroid 
back to the shack with a common VOM. This is an easy troubleshooting  
tool that is not possible via the DXE system.

Herb, KV4FZ





On 3/23/2012 11:10 AM, Kenneth Grimm wrote:
> I'm in the process of building a new two wire beverage control box to
> replace the one that Thor destroyed the other day.  Fortunately the coax
> lead in was disconnected at the time!  The top of the box has not been
> recovered and much of the contents vaporized.  The inside of the box has
> lots of scorch marks...and not much else.  The reflection transformer, some
> 580 feet away, appears to be unaffected as does the 450 ohm twin lead.
>
> I plan to do a PC board for the new control box and so I had a look at how
> the DX Engineering box was laid out.  I also had a look at the board made
> by RA6LBS.  Both of these boards appear to have an electrolytic capacitor
> installed.  On both boards the electrolytic appears to be associated with
> the direction switching relay.  None of the two wire beverage diagrams that
> I have seen have such a cap and I wonder what its function is and how it is
> connected in the circuit.  I am told that the value is 100 mfd @ 50 volts.
>
> Apparently the cap isn't necessary, but since I have a few in my junk box,
> this might be an opportunity to put one of them to use!
>
> 73,
>