WAMG night power increase

[chrish]

This is for Dan Strassberg and the many others who find such information interesting. I received a call tonight from Jessamy Tang and Len Weiner who were
on another line with the stations Washington attorneys.
WAMG received permission from the FCC to increase the power to 6 KW using the new night pattern.
I will try to do this Friday night but if not It will likely be done while doing my
weekly inspection sometime on Saturday or Sunday.

Also the other new WLLH Lawrence Harris DAX-1 is on its way and will be on the air soon.

Chris Hall

 

[DanStrassberg]

This is for Dan Strassberg and the many others who find such information interesting. I received a call tonight from Jessamy Tang and Len Weiner who were
on another line with the stations Washington attorneys.
WAMG received permission from the FCC to increase the power to 6 KW using the new night pattern.
I will try to do this Friday night but if not It will likely be done while doing my
weekly inspection sometime on Saturday or Sunday.

Also the other new WLLH Lawrence Harris DAX-1 is on its way and will be on the air soon.

Chris Hall

Chris: Once I saw that the FCC had accepted both of WAMG's apps for filing (the app to modify the CP to very slightly augment the new night pattern and the app for a license to cover the upgrade), I assumed--apparently incorrectly, it seems now, based on the post to which I am replying--that WAMG was operating with its CP facilities, and probably had been doing so for a minimum of several weeks before notification of the acceptance of the apps for filing appeared in the FCC Daily Digest. But knowing what I do about the implementation of the new pattern (via component changes in the night phasor and NOT by replacement of that phasor), WAMG must have been running the new pattern for quite a while--but probably at less than 6 kW--maybe at the former 3.4 kW or maybe even less. If that's so, where I live (~16 miles from the site at an azimuth of just about 45 degrees), I'm quite sure that there has been a noticeable improvement in the night signal even without the power increase. I still hear WLS underneath WAMG on most nights, but the interference is never great enough to make listening unpleasant and certainly never great enough to impair intelligibility. My preception is plausible, because the new night pattern--even if you ignore the new minor lobes to the north and south--is somewhat fatter than the old one, so I think there is some gain in signal strength here even without the power increase. Without the power increase, the signal strength at the pattern maximum due east of the site would be less than with the old pattern, however, especially since the north-south high-voltage ac transmission line about a mile east of the site was detuned to minimize its effect on the critical parts of the pattern to the west of the site. Detuning the ac line apparently eliminated a huge augmentation over an arc of about 90 degrees directly to the east.

 

[raccoonradio]

Here's the tech. info from radio-locator.com (any maps involved should be taken with a grain of salt)

WAMG
http://radio-locator.com/cgi-bin/finder?call=WAMG&x=0&y=0&sr=Y&s=C

You can click on the current pattern and the CP pattern to see the difference. Again, not sure exactly
how accurate these will be--and for some, like Dan, WLS could be in the background. Up on
the North Shore it wasn't quite so noticeable.

As for WLLH:
>>Also the other new WLLH Lawrence Harris DAX-1 is on its way and will be on the air soon.

Is WLLH using its synchronous (I think that's the word) xmtr in Lawrence at all?
I usually don't listen to 890 and 1400 but coming soon are baseball playoffs and in the first round
there will be games at 1* or 4 pm (early Oct.) which I would hope they'd carry (though they'd have to
pre-empt local talk with Felger). Anyway while on the North Shore (think Rt 128 from Beverly to
Reading) I notice 890 is fairly strong days (haven't really checked nights) and for a short while
it looked like 1400 wasn't bad (DAYS)...though I'm hoping the new piece of equipment Chris mentioned
will help (at my workplace in N. Reading, and I work nights, I was straining last year to pick up
some non-Red Sox baseball playoff action from NYC stations since 890/1400 didn't quite come in
well...well, for one game 890 was OK...)

But a transmitter in Lawrence might help. By the way the radio-locator page only has a map for
the Lowell xmtr..for now.

*--well, usually for a day or so, then they go to 4 pm, 8 pm, and perhaps even 11 pm in the first
round, AL and NL Divisional Series...

(Of course Red Sox playoff games will be no problem; last year I was able to get Mets via WFAN
("Let's go Mets! F-A-N...") and Yankees playoffs via WCBS and WPOP Hartford...while it might hurt
my reception situation, I'm hoping (sorry Yankee fans) that the Yankees will not be involved this year!
(Don't feel sad...just think, 26 trophies for you...) Though I could still pick up ESPN Hartford (WPOP)
for some games.

 

[DanStrassberg]

Here's the tech. info from radio-locator.com (any maps involved should be taken with a grain of salt)

At least in the case of WAMG's night operation, you should take those maps with something more like a peck, rather than a grain, of salt. Just DON'T believe them! If you study the maps for the 3.4-kW and 6-kW coverage, you will find that, with the exception of the 6-kW contours' new north and south minor lobes, each ENTIRE 6-kW contour fits within the equivalent 3.4-kW contour. In reality THAT JUST WON'T BE TRUE! According to those maps, the 6-kW night signal where I live (Arlington Heights on the Lexington line, about 0.5 miles north of Route 2) will be slightly LESS than the 3.4-kW signal. Not so! The azimuth from the WAMG Tx in Ashland to my house is approximately 45 degrees. The 6 kW signal along that azimuth will be about 1.45 times the old 3.4 kW signal. Since field intensity increases as the square root of the power, at 6 kW, the effective power along that azimuth will be the equivalent of a more than a 2X increase in power (1.45^2 = ~2.1). There is NO WAY that twice the equivalent power will put the new contour inside the old one! That may not be true, however, due east of the Tx. There, there used to be (or there was supposed to be) a huge augmentation in the old night pattern that more than doubled the effective power in that direction. The augmentation fell off gradually over about 45 degrees to the north and south before disappearing completely. Several of us doubt that such an augmentation ever really existed because there was NO corresponding augmentation to the day pattern. The station needed the night augmentation to be able to claim that it delivered an adequate nighttime signal to Dedham so it could be licensed to that community. In other words, there could have been some fortuitous errors in the original proof-of-performance measurements many years ago. Whether the augmentation was real or imaginary can no longer be proven because the alleged cause was reradiation of the signal from a high-voltage AC transmission line that runs north and south about a mile east of the site. That transmission line has now been detuned to suppress reradiation and allow proper adjustment of the pattern to the west, where it really needs to work to avoid interference to WLS.

BTW, without benefit of any augmentation to the east, the new 6-kW night pattern produces an inverse-distance field at 1 km of over 2300 mV/m. That's ~20% more than the equivalent of 50 kW ND into a nondirectional antenna of minimum efficiency for a Class B AM (which is what WAMG is). In other words, WAMG's 6-kW night signal due east of Ashland (at the signal maximum) can be said to be the equivalent of ~70 kW! (The reason is the gain from the relatively narrow pattern coupled with the very high efficiency of the 173+-degree towers.) WAMG will deliver the requisite NIF (nighttime interference-free) signal to more than the required 80% of Dedham without benefit of any fortuitous augmentations. As a rule of thumb, AM signals have been considered quite acceptable at night at a field strength of half the official NIF value (and have generally been listenable at even lower signal levels). Whether the old rules of thumb will hold true in the impending era of nigttime IBOC has yet to be determined. WCBS's upper IBOC sideband may do a number of WAMG and if WAMG fails to get on WCBS's case for generating prohibited interference, then shame on WAMG.

 

[Laurence Glavin]

Seventy-kilowatts to the east! Then it should have a killer signal in Boston itself at night. Cambridge and Somerville too? I'm certainly not going to drive into Boston to test it myself, only if my travels take me there.

 

[DanStrassberg]

Seventy-kilowatts to the east! Then it should have a killer signal in Boston itself at night. Cambridge and Somerville too? I'm certainly not going to drive into Boston to test it myself, only if my travels take me there.

Remember that distance (from the signal source--the transmitter site) and soil conductivity are important parts of the signal-strength equation. I didn't get out a map, but I believe that Sewell St in Ashland is about 30 km from the waterfront in downtown Boston--a long way considering the miserable soil conductivity in southeastern New England. I then went to the V-Soft web site and entered Zip code 02101, which I believe is the Zip of the South Boston Postal Annex, which is not far from the downtown waterfront. Currently, V-Soft lists WAMG's nighttime signal-strength in 02101 as 4.84 mV/m. (Daytime is 11.52). The ratio of day to night, 2.38:1, is close to the ratio of the current day and night augmented-pattern inverse-distance fields at 1 km at azimuths slightly north of due east (the direction of downtown Boston from Ashland), but I did not find any azimuth where the ratio was exactly 2.38:1; the ratios were a bit lower. The conclusion I draw, however, is that since the 6 kW signal strength in that direction is about the same as the 3.4 kW pattern's augmented field in that direction, you probably won't notice a huge change--UNLESS the augmentation of the old pattern was indeed erroneous. So the 5 mV/m (or so) signal that you are likely to pick up downtown will not be overpowering, and will be considerably less than the NIF field of 12.5 mV/m. Still, based on my nighttime reception in Arlington, if you pick a spot that's not inside of or shadowed by a steel-framed skyscraper or bothered by too much electrical interference (say, from computers), the signal is likely to be listenable although WLS is likely to be audible in the background.

 

[DanStrassberg]

I will try to do this Friday night but if not It will likely be done while doing my
weekly inspection sometime on Saturday or Sunday.

Chris Hall

Hi, Chris: I've never been able to say for sure that the new pattern/power were or weren't on on any particular night. The fact is, I had convinced myself that the new pattern alone--even at the old (or lower) power--was an improvement. However, I THINK WAMG sounded louder beginning on Friday night/Saturday early AM and I am even more convinced that the new setup was on the air last night (Saturday night/Sunday early AM), but confirmation from the guy who REALLY knows would be most welcome!

 

[mgpt6]

9/14/2007 is a key night. Will AMG get whacked by WCBS 880AM's upper IBOC band.

 

[DanStrassberg]

9/14/2007 is a key night. Will AMG get whacked by WCBS 880AM's upper IBOC band.

One night may or may not tell the story. We're talking skywave--a phenomenon that varies almost minute by minute. If 9/14 is a good night for skywave, we COULD have an answer very quickly. But if it's not a good skywave night, it won't prove that the interference won't be a problem on some other nights--especially during the winter. To put it in the most dramatic terms, we could say that 9/14/07 will be the AM band's equivalent of 9/11/01. At least nobody is going to die from IBOC (although some who lose their jobs because of it might starve to death eventually).

 

[chrish]

At pattern change tonight at I reset the night power level for a
common point of 11.24 amps, unfortunately I was on a family phone call all the way to NH that lasted until after I got home and was not able to listen. It may take a good bit of time to make an assessment. The only sure thing I have learned during my 8 or so years involvement with 890 is the is no sure thing. Radically different from night to night.
Some nights perfect signal all the way to NH, 24 hours later no sign of WAMG
whatsoever, at times even in the studio parking lot at times just WLS cranking away.
Could reliably use the Belar AMM-2 with RFA-1 and the amplified loop during the day, at night it was anyones guess if it would be WAMG, WLS or neither one or
some combination of both with one or two others in the backgroung just for fun.

 

[DanStrassberg]

Does WAMG use one of those modern, solid-state transmitters whose carrier frequency is digitally synthesized and referenced to a very stable frequency distributed as a signal from GPS satellites? If so, you would be able to adjust the carrier frequency in tiny incements. Did you recently nudge the frequency up or down by a few Hz? If not, maybe WLS did it. My impression is that the WAMG and WLS carrier frequencies differ by a few Hz more now than they did a week or so ago. And I think the result is an improvement. That is, WLS, which was rarely bothersome here, is less annoying under WAMG now than it was. Of course, the increase in the signal level could be responsible. Based on V-Soft's numbers, WAMG's night signal in my Zip code goes from 4.06 mV/m at 3.4 kw with the old pattern to about 5.75 mV/m at 6 kW with the new pattern. 5.75 mV/m is just a little less than half the NIF, which means that the signal should be subject to audible interference but, rarely, if ever, at a bothersome level. That seems to be the case, but it was also the case before you raised the power.

 

[chrish]

Dan, the transmitter is a nine year old Harris DX-25 (same box as a DX-50 with
a row of broadband PA cards removed) I just ordered a replacement tonight
for one that may have taken a lightning hit.
Have not done any tweaking on the frequency lately, Rick Levy keeps a monthly eye on it, oscillator has always been rock stable though he would give a call if it started moving in either direction.