New Benefits of HD Radio - Frying Transmitters

Computer, engineering, and other technical assistance.

Moderators: genlock, sportsvoice

Post Reply
Cameron
Member
Member
Posts: 887
Joined: Fri Aug 09, 2002 8:41 am
Location: Birmingham Ala-BAMA!
Contact:

New Benefits of HD Radio - Frying Transmitters

Post by Cameron »

You think this holds any weight?
From Radio-Info:
Obnoxious, fatiguing artifact-laden codec. High costs. Self-interference and analog noise. Adjacent-channel interference. Encoding delay. Limited digital coverage. Necessitates drastically reduced analog bandwidth. Won't work with a large percentage of existing directional arrays. Engineers hate it; listeners couldn't care less.

To these well-known HD-AM features we can now add: IBOC-AM can damage power modules in the latest generation Harris 50kw transmitter, the 3DX-50.

There have now surfaced an increasing number of accounts - of course, in typical HD fashion, being forcibly hushed by IBOC powers-that-be - that the HD encoding and COFDM system can cause transient drive failure to MOSFETS in the PA modules of the popular high-power Harris AM transmitter being used by a large number of HD-equipped stations. Result: PAs shut down, forcing reduced-power operation until an engineer can make repairs.

There is at least one account of a 50kw midwest station that operates its older-generation transmitter - that's right, a BACKUP - because it's less susceptible to PA damage from HD encoding. Which of course means that the shiny new 3DX-50 is relegated to the status of being an expensive standby TX!

An unnamed source in the tech-support department at Broadcast Electronics stated that he was truly thankful for HD Radio. Without HD, the number of employees required to deal with technical problems and issues would likely be halved.
------------------------
Cameron Smith - CSRE®
Senior Member - SBE 68 Birmingham
Senior Digital Product Manager - Hibbett Sports|City Gear
Tom Taggart
Member
Member
Posts: 768
Joined: Tue Dec 18, 2001 11:30 am
Location: Marietta, Ohio

Post by Tom Taggart »

Well, think about it. Ever try doing a proof on a plate modulated transmitter? How did it like 10 KC at full modulation? HD goes out to 19 kc (the 1000 demonic cicadas sound on the second adjacent channel).

Sure, the more modern rigs have the bandwidth to pass information that high in frequency. But I bet they don't like it!
Cameron
Member
Member
Posts: 887
Joined: Fri Aug 09, 2002 8:41 am
Location: Birmingham Ala-BAMA!
Contact:

Post by Cameron »

Tom Taggart wrote:Well, think about it. Ever try doing a proof on a plate modulated transmitter? How did it like 10 KC at full modulation? HD goes out to 19 kc (the 1000 demonic cicadas sound on the second adjacent channel).

Sure, the more modern rigs have the bandwidth to pass information that high in frequency. But I bet they don't like it!

That being the case, subtile antenna changes could be disastourous on so many levels.
------------------------
Cameron Smith - CSRE®
Senior Member - SBE 68 Birmingham
Senior Digital Product Manager - Hibbett Sports|City Gear
sportsvoice
Moderator
Moderator
Posts: 387
Joined: Sat Dec 15, 2001 10:06 am
Location: O-H...

Post by sportsvoice »

I wonder if running IBAC through the backup makes it eat tubes like crazy.
Post Reply