Some things I think I think

[Larry Acklin]

I was installing a fixed dish this weekend to pick up galaxy 15 (?) Old I-5 and noticed a few things I thought I'd pass on.

A 30" fortec dish is marginal at my location in SW PA, but I am able to get about 135 channels., 21 transponders.

I adjusted skew by tuning a fairly strong transponder, and doing the skew adjustment until I thought it was peaked. Then I pulled or pushed the LNB in or out until I was out of the focus point, noted a drop in quality, but still locked.

The skew became much more touchy, and I found there was only one place I could maintain lock and reasonable quality numbers. Once I had that skew setting, I pushed the LNB back in (or out) until the quality number peaked.

I'm using an old FortecStar Lifetime Ultra recently flashed to factory code, and I got 85 strength, 74 qual on the strongest channel (God Channel I believe).

The lnb arm is bendable- pushing up or down can change the quality number quite a bit- almost an adjustment in itself if the dish is locked hard. No side braces on this model. (80 cm).

Then the fun started. I blind scanned and got only a few transponders, and the quality numbers were way down. About that time I decided to go inside, as I was getting cold.

Then it hit me- These receivers are made to hit a (low) price point, and the temperature co-efficents on the tuners and such are probably really poor. I was tuning with a receiver in 50 degree (f) weather, and as the receiver cooled off,the tuning was drifiting also. Mhz Worldview, usually easy to get, was in breakup by the time I tuned it in after 25 mins of blind scan.

So I hooked the dish to the DiseQ switch, came inside, and scanned using the warm Mercury II, and got 21 transponders, 135 channels, etc. All good.

So- keep that receiver temp stable if you can when tuning outdoors this fall.

Larry

[wejones]

Originally Posted by Larry Acklin

I was installing a fixed dish this weekend to pick up galaxy 15 (?) Old I-5 and noticed a few things I thought I'd pass on.

Galaxy 15 is at 133, and is where the old Galaxy 1r used to be.
I-5 used to be Panamsat 5, and used to be over the Atlantic, but is now over Europe.
I assume that the above is a typo, and you meant Galaxy 25, which used to be IA5 or T5?

Originally Posted by Larry Acklin

A 30" fortec dish is marginal at my location in SW PA, but I am able to get about 135 channels., 21 transponders.

I adjusted skew by tuning a fairly strong transponder, and doing the skew adjustment until I thought it was peaked. Then I pulled or pushed the LNB in or out until I was out of the focus point, noted a drop in quality, but still locked.

The skew became much more touchy, and I found there was only one place I could maintain lock and reasonable quality numbers. Once I had that skew setting, I pushed the LNB back in (or out) until the quality number peaked.

I'm using an old FortecStar Lifetime Ultra recently flashed to factory code, and I got 85 strength, 74 qual on the strongest channel (God Channel I believe).

The lnb arm is bendable- pushing up or down can change the quality number quite a bit- almost an adjustment in itself if the dish is locked hard. No side braces on this model. (80 cm).

Then the fun started. I blind scanned and got only a few transponders, and the quality numbers were way down. About that time I decided to go inside, as I was getting cold.

Then it hit me- These receivers are made to hit a (low) price point, and the temperature co-efficents on the tuners and such are probably really poor. I was tuning with a receiver in 50 degree (f) weather, and as the receiver cooled off,the tuning was drifiting also. Mhz Worldview, usually easy to get, was in breakup by the time I tuned it in after 25 mins of blind scan.

So I hooked the dish to the DiseQ switch, came inside, and scanned using the warm Mercury II, and got 21 transponders, 135 channels, etc. All good.

So- keep that receiver temp stable if you can when tuning outdoors this fall.

Larry

Interesting. When you did the blind scan outside, did the frequencies that came up for the transponders differ much from what you came up with when you came inside?

I would have guessed that perhaps outside where it was cool, the frequency might have drifted a bit in the receiver. However the Ultra is able to lock transponders when WAY off frequency, and the Mercury is similar. So it must be something else besides just frequency drift. Anyway, I'm surprised that you observed much difference for such a small difference in temperature. My Ultra occasionally runs close to 50 deg, since it's in my basement that isn't heated, but I've never noticed anything similar that might have been related to temperature. Although my Ultra is sitting on top of a stack of 3 or 4 other receivers, so they may be keeping it warm.

But you are illustrating why mil-spec electronics are so much more expensive than consumer electronics. Before I retired, I used to test military electronic devices at extreme temperatures (-40 up through about +120 or more), and most things we tested didn't perform very well.

[Larry Acklin]

Yes, Galaxy 25, the IA-5 international. The transponders that seemed to be off were the weaker ones, and I suspect the LNB drift (cold/unpowered until I aligned the dish) and the receiver drift were causing the poor quality numbers. I had lock, else I would not have had picture at all.

I had severe breakup on channels I can usually get in well, even on a smaller dish. The BUD with Ku seems to be the best bet for DXing, and I just set up the 80cm so I can surf channels on G25 without repointing the big un. (normally on NASA C band feed)

I did some testing for industrial electronics in the later 70's and we had a -40 to +70 spec. We had to do some major tweeking and design work to get (close) to there.

And a chamber with a forced air heater and CO2 spray to chill.

Larry

[wejones]

Originally Posted by Larry Acklin

Yes, Galaxy 25, the IA-5 international. The transponders that seemed to be off were the weaker ones, and I suspect the LNB drift (cold/unpowered until I aligned the dish) and the receiver drift were causing the poor quality numbers. I had lock, else I would not have had picture at all.

I had severe breakup on channels I can usually get in well, even on a smaller dish. The BUD with Ku seems to be the best bet for DXing, and I just set up the 80cm so I can surf channels on G25 without repointing the big un. (normally on NASA C band feed)

I did some testing for industrial electronics in the later 70's and we had a -40 to +70 spec. We had to do some major tweeking and design work to get (close) to there.

And a chamber with a forced air heater and CO2 spray to chill.

Larry

I guess your -40 to 70 was centigrade, which corresponds to -40 to 158 F . I think that's pretty similar to what we were aiming at, which I think was mil spec 810e or something like that. I had remembered 120, because I think that's as high as we went in the particular chamber I worked with, but we had another chamber that we took higher. The other chamber just did temperature and solar, but my chamber did humidity as well. It was a pretty neat chamber, that was about 5'x5'x8' inside, and was hermetically sealed, because we tested nerve gas detectors. We could program the thing to go through all sorts of preprogrammed cycles of temperature/humidity. I can't remember how it cooled, I think just via regular freon refrigeration.

Before that job, I used to work at a place where I had a gas chromatograph that used CO2 spray for subambient cooling. One night I was working late, and ran out of CO2, so I emptied about 8 CO2 fire extinguishers to finish the job. Next day I kind of got in trouble with the company's safety guy, who was upset because he had to fill out fire reports or something whenever an extinguisher was used.

Re consumer stuff handling temperature changes, I had an LNB once that went into oscillation whenever the temperature hit 15 deg outside, and I'd completely lose reception. I'd have to turn the thing off and back on to get it working again. I eventually had to hook up an X10 switch to turn it off, since the receiver it was on kept power to the LNB even when switched off. Also, I have one of the cheapest lnbfs that Sadoun sold, and it drifts about 5 MHz when it gets cold. My big dish lnbs only drift about 1 MHz.