[TowerTalk] ICE 419B schematic

[N2TK, Tony]

Someone gave me a tip a number of years ago about checking out 419 filters.
He said to take off the cover and stick your nose in the box and see if you
have a burnt smell. And look at the color of the caps and see if some are
quite dark in color from excessive current.

Now use W3NQN transmit and receive filters. Overall seem to work much
better.

73,
N2TK, Tony

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of K1TTT
Sent: Tuesday, July 19, 2011 6:15 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] ICE 419B schematic

Again, its probably not the voltage but the current that is the problem...
See my last message.  

Also on mine the capacitors on 20m hadn't 'failed' they had shifted value...
It was obvious to see using a minivna to sweep the filter that it was still
there, it just wasn't resonating where it what supposed to any more.  In
mine the 10m section had one of the shunt caps shorted, the others were ok,
but I replaced them all anyway.  The 20m section had one of the shunt caps
changed from 1000pf to 247pf on a handheld dmm, my mfj 269 reads it as 614pf
at 2mhz but is highly frequency dependent where the good one is a stable
1040pf or so over a wide range.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: Mark Ketchell [mailto:k5er at arrl.net] 
> Sent: Tuesday, July 19, 2011 21:48
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] ICE 419B schematic
> 
> 
> Okay, I'll ask too...
> 
> The 20 meter section of my ICE 419b failed - infinite SWR.
> 
> I removed cover from relay and polished contacts, eliminating 
> it as the 
> possible failure point.
> 
> Inductors - still same size and shape, can't be them.
> 
> Pulled the 3 caps and took to elec supply store. All 3 
> checked good on 
> their tester (had them check twice). Took to friend with HP 
> meter. The two 
> shunt caps (.001 @ 2kv) each checked fine - the 270 pf (+/- 
> 5%) checked as 
> 251 pf - about 7% off. Would have thought it was close enough 
> to find a 
> resonate point, but it would not.
> 
> I simply replaced all three and it works just like new.
> 
> Why would the caps check as okay, but be absolutely worthless in the 
> circuit?  IF it is the series cap (270pf at 1kv) that fails, then why 
> doesn't it ever seem to take the .05 @ 200v series cap right 
> at the antenna 
> port? If not the series cap, how does a 100 watt radio 
> generate enough 
> voltage to cause a 2kv cap to fail? There are resonate auto-switched 
> antenna on each band, so it "shouldn't" see high SWR.
> 
> Thanks,
> Mark
> 
> 
> ...
> >What usually happens when the filter fails is that one or both of
> >the capacitors on the radio side of the Pi changes value.
> >
> >Mouser has a good selection of heavier-duty replacement caps.
> >For example, Mouser part number 5983-19-1KV330 for 15 meters.
> >Even with those, the filter can still fail.
> >
> >Dave Hachadorian, K6LL
> >Big Bear Lake, CA
> >
> >
> >-----Original Message-----
> >From: James C. Hall, MD
> >Sent: Monday, July 18, 2011 2:28 PM
> >To: towertalk at contesting.com
> >Cc: tcg1 at googlegroups.com
> >Subject: [TowerTalk] ICE 419B schematic
> >
> >Hello:
> >
> >I sent an email to ICE inquiring about their ability to repair my
> >ICE 419B's
> >which have a couple blown filters. I got a response that since
> >Mike died,
> >they can't repair anything right now.
> >
> >I asked about a schematic of these 2-stage filters and they came
> >back with
> >'they don't have them either', which I found rather strange. At
> >any rate,
> >does anyone have a schematic or parts list of the 419B so that I
> >may attempt
> >to fix them myself ?
> >
> >This may or may not be the correct forum to send this, so if not,
> >please
> >advise and I'll redirect this.
> >
> >Thanks.
> >
> >73, Jamie
> >
> >WB4YDL
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> 


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