[grc] LPFM transmitter advice

[Michelle Bradley]

I concur with Paul's statements in respect to the use of the FX-30.  
This is not a type certified piece of equipment and should not be used 
long term. If inspected, the FCC is going to look for an FCC ID number 
on the transmitter and since there is not one there, you may get a 
Notice of Violation.

With the new functionality in LMS, you may want to file a Reduced Power 
Notification (you can find it in the dropdown by going to Facilities and 
clicking on your facility). If you need assistance, please contact Paul 
or myself.

-- 
*Michelle Bradley, CBT, KU3N*
/Founder: REC Networks/
+1 202 621-2355
https://recnet.com
facebook.com/recnet - Twitter: @michichan

On 5/25/2022 11:56 AM, Paul Bame via grc wrote:
> 1. That Nicom is fairly simple so I've no doubt it can be repaired by Nicom
> or by some others who do that sort of work (I don't have names though, and
> it's been a while since I had one open).
>
> 2. It's not clear to me if "degraded signal or silence" refers just to
> audio problems, or to the forward+reverse power as well -- guessing the
> former.
>
> 3. Problems with audio like that are frequently due to cable+connector
> issues. I'm sure you've already checked all the connectors in the audio
> path (inside and outside the TX) for corrosion/oxidation, shorts, and
> failing solder joints. Those symptoms can vary with moisture or temperature.
>
> 4. Mysterious problems in equipment that age almost always demand
> evaluation of especially the larger electrolytic caps in the power
> supplies. Re-capping is a very common repair, and might be a part of any
> "reconditioning" anyway. Easy to DIY too.
>
> 5. An easy and sometimes-fruitful check is to put a 'scope (or a voltmeter
> set to /AC/) on all the DC power rails (especially near that audio chip).
> When power-supply filter caps fail, you can sometimes see it as an
> appreciable AC voltage with this test even while a DC voltmeter might also
> show the right voltage.
>
> 6. The FX-30 I doubt is approved for LPFM, plus the temporarily-lower
> power... an engineering STA application might be wise.
>
> 7. To fully flesh out an older transmitter like that, I'd add an external
> audio processor and a phone and/or web interface to monitor power etc and
> do basic transmitter remote control (BT WVRC4, Burke, Sine Systems). New
> transmitters put audio processing, RDS, settings, control and monitoring in
> one integrated web-controllable package. My current recommendation is the
> Ecreso line by Worldcast Systems (given the demise of BW) unless someone
> wants to drop another couple $K on a Nautel or something.
>
>
> ##
> Paul (he/him) (pablito) Bame
> Engineering Director, Philadelphia, Prometheus Radio Project
> <http://prometheusradio.org/>
> 215.727.9620 x2 / 970.988.3849
>
>
> On Wed, May 25, 2022 at 9:12 AM Robert Park via grc<grc at maillist.peak.org>
> wrote:
>
>> For more than a decade WIDE-LP in Madison WI has operated successfully with
>> a reconditioned NiCOM NT 250/LCD transmitter. In recent weeks we have had
>> an increasingly serious problem with periods of degraded signal or silence
>> followed by spontaneous recovery. We have traced the problem up the line as
>> far as the audio chip in the transmitter. As a result we have switched out
>> the NiCOM for an older FX 30 that now has us reliably back on the air, but
>> at half our allowed 100 W ERP.
>>
>> To return to normal operation we need to decide whether to repair,
>> recondition or replace the NiCOM. Advice from this list would be
>> appreciated.
>>
>> Is there anyone in Wisconsin who could determine whether the audio chip in
>> the NiCOM is the whole problem? If it is, would repairing the NiCOM by
>> replacing that chip be a viable option?
>> Is anyone else operating an LPFM station with a NiCOM transmitter?
>> If we decide to repair or recondition the NiCOM is there a place in the
>> midwest folks would recommend for doing it? Would it be best to ship the
>> NiCOM to the company<https://www.nicomusa.com/>  in San Diego CA?
>>
>> Bob Park
>> Program Director
>> WIDE-LP 99.1 FM
>> http://widelp.org/
>> email:radio at widelp.org
>> https://twitter.com/WIDE_LP
>> https://www.facebook.com/WIDE.LP.99.1/