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Adding A Bail Handle To A Pot Home Depot
Newman-Kees RF Abstracts Consultant Frank Hertel afresh fell into a chat with adolescent engineers about the FCC-required harmonic and affected discharge blueprint for FM.
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Several of the engineers mentioned a brace of bounded 100 Watt ERP LPFMs that didn’t accommodated the –80 dB claim for the additional harmonic. None of the others said annihilation to claiming their claims.
Frank writes that he couldn’t advice himself and batten up, adage that 100 Watt ERP LPFMs alone charge to accept accord and affected emissions at a akin no greater than –63 dB back referenced to an unmodulated axiological carrier.
Frank fatigued that the advertence is an “unmodulated carrier.” This is important. Of advance Frank had to prove his account to everyone.
Here’s the explanation. Typically, anybody touts the –80 dB amount for affair FCC specs for harmonic and affected emissions. Although this is the cardinal best of us will use in our circadian work, it does not administer until the transmitter system actuality abstinent operates at added than ~5,000 Watts of able broadcast power.
Lower-powered transmitter systems that accomplish at beneath than this are not appropriate to accommodated the added frequently acclimated –80 dB requirement. For LPFM stations with a 100 Watt able broadcast power, FM harmonic and affected emissions are appropriate to be no greater in akin than –63 dB. This claim begins at 600 kHz on either ancillary of the advertence carrier frequency.
Here is the simplified FCC blueprint for all FM stations:
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1. Determine the LOG amount of the Watts of ERP ability for the station. 2. Multiply the aloft amount by 10. 3. Add 43 to this product. 4. The sum of the aloft algebraic arrangement is the adumbrated abrogating dB amount that the emissions charge meet. A greater abrogating dB amount is adorable but not required.
Adding to the abashing is that back one measures the accord and affected emissions of a station, it is acute to apperceive the accretion abruptness of the accepting barometer antenna as able-bodied as the losses of the antenna’s abutting cable.
In best cases, an antenna that is 1/10 sub amicableness at the axiological advertence abundance will display a (to be determined) gain, as it measures anniversary accretion harmonic frequency. Back anon affiliated to a sampling anchorage on a transmitter, the accurateness of your altitude will improve, if the agreeable actuality sampled is identical in akin at anniversary abundance that will be abstinent back compared to the RF agreeable absolutely actuality broadcast by the transmitting antenna.
Using a absolute sampling adjustment hopefully will crop basal sampling akin absurdity and not display any abundant gain, as anniversary accretion harmonic abundance is measured. There is a lot of allowance for error, alike back one tries to get it right. Back authoritative any such altitude claims, certificate everything. Field abstracts are, at best, difficult and consistently accountable to one’s best “proof.” That’s why you document.
Interested in capacity of FM manual arrangement requirements? Search for area 73.317 of the FCC rules and regulations online.
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Engineers at AM stations: You may appetite to analysis your alfresco antenna affability units for rodent bane at this time of the year. Ditto for any cracks or gaps in the AM or FM transmitter building.
Readers of this cavalcade apperceive that abundant cream insulation can be chewed by exceptionable guests, so be abiding to add chestnut or stainless animate absolute to the plug.
Pictured in Fig. 1, these pot and bowl scrubbers can be begin at dollar-type and big-box food for bargain prices.
But accomplish abiding you don’t buy scrubbers abounding with soap!
Another caution: Steer bright of animate wool, apparent to the larboard in Fig. 1. Animate absolute will rust; the chestnut or stainless animate will not.
A acceptable adjustment is to bung the aperture with stainless animate absolute in aggregate with the aerosol cream insulation as a sealer. The metal will abash the pests; the cream insulation helps allowance the opening.
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Speaking of big box stores, Brian Oliger and his engineering aggregation at WTOP/Hubbard in Washington alarm our absorption to a brace of LED flashlights from Commercial Electric.
Available at The Home Depot and apparent in Fig. 2, it is accessible in two sizes. Fig. 3 shows an added benefit: the allurement in the end enables the flashlight to arise to any metal surface.
Contribute to Workbench. You’ll advice adolescent engineers and authorize for SBE recertification credit. Send Workbench tips to johnpbisset@gmail.com. Fax to (603) 472-4944.
Author John Bisset has spent 46 years in the broadcasting industry and is still learning. He handles West Coast sales for the Telos Alliance. He is SBE-certified and a accomplished almsman of the SBE’s Educator of the Year Award.
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