Topband: cutting coax stubs for 80 meter 4-square

[Grant Saviers]

On a couple of DXpeditions we damaged the front end of a couple of 
analyzers by transmitting on a nearby antenna on a different band so 
this is another hazard to be aware of.

Grant KZ1W

On 6/11/2018 10:14 AM, terry burge wrote:
> Jim,
>
> There is room that the 0.01-0.02uF cap could go in. Due to the surface mount circuitry I would want to take the wire itself to the SO-239 and install it there rather than try mounting it on the board. But I would definitely remember to short the antenna/coax connection just to protect from static electricity. A dedicated flexible coax installed semi-permanent is a pretty good idea too. But I keep my AA-170 in one of those metal carrying cases from Harbor Freight with associated accessories with thick foam. That could make having something hooked up all the time to the connector could be a problem.
>
> Terry
> KI7M
>
>> On June 11, 2018 at 9:50 AM Jim Thomson <jim.thom at telus.net> wrote:
>>
>>
>> Date: Mon, 11 Jun 2018 07:29:39 -0700
>> From: "Richard (Rick) Karlquist" <richard at karlquist.com>
>> To: terry burge <ki7m at comcast.net>, topband at contesting.com
>> Subject: Re: Topband: cutting coax stubs for 80 meter 4-square
>>
>> On 6/10/2018 8:01 PM, terry burge wrote:
>>> All's well that ends well I'm happy to report. K2AV, Guy suggested I check the SO-239 on the Rig Experts AA-170 and I found an open solder joint between the back of the connector and the circuit board. Even with my close in glasses and a magnifying glass it was hard to be certain. So a little solder and 'hop-a-long' rides again! It's working. Will check out the coax stub again to see what the RE reads now.
>>> Terry
>>> KI7M
>> <My AA-55 is a different model than yours, but the instructions
>> have curious warning about not putting too much force on the
>> UHF connector.  I am thinking that RE realizes they have a
>> weak mechanical mounting, relying on solder.  I think I will
>> revise my advice:
>>
>> 1.  Always use a DC block
>> 2.  Carefully attach a short flexible coax jumper and leave
>> in place.  Calibrate it out.  Then connect the DUT to the
>> end of the jumper.  No mechanical stress on the UHF.
>>
>> Rick N6RK
>>
>> ##  Is there room inside those  rig experts units to install a .01 uf disc ceramic  cap ??
>> A  50-100  volt  cap would be smaller diameter than a 1 kv  cap.   There is  your  DC
>> blocking right there.  .01uf  = 10,000  PF..which  is ample.  .01uf  = just  8.846 ohms of  XC
>> on  1.8 mhz...and  WAY less Xc, when on higher freqs.... like 4 ohms on 80m..and  2 ohms on 40m.
>> If a .02 uf cap was used, the XC  would be half again.
>>
>> ## On a similar note,  re the MFJ-259B.   Can  a HP filter be used, to kill  AM broadcast
>> junk...or  will the HP filter  screw things up too much ?
>>
>> Jim  VE7RF
>>
>>
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