Old round DirecTV dish -- salvagable for FTA use?

[rmccolman]

Hi guys,

Aside from my Orby dish that I've repurposed for FTA use and a new GeoSatPro 1.2m that I've just ordered, I have an old DirecTV dish -- the original round standard def dish -- sitting around. Question: if I were to mount a linear LNB on that dish, is there any FTA KU band satellite content strong enough for it to pick up, or is it merely "boat anchor" material.

I figured this is probably a long shot at best, but just thought I'd check anyway.

Thanks - Richard

 

[Brct203]

not sure how large that DirecTV dish is, but with a DN Dish 500 dish (18 inches, if I remember correctly), I was able to somewhat reliably get the CCTV mux on 95W, the NHK mux on 103W. Might not work so well during a downpour or heavy snow, but should be ok most of the time. Reception of 97W was less reliable, possibly due to adjascent satellite interferences. Might be ok as well for KBS on 123W, but I think they might have lower power now that a few years ago

 

[rmccolman]

As I recall, it is 18" in diameter, though I'll have to double-check that tomorrow morning.

Thx

 

[Redbullsnation]

Should be fine with KuBand, I'm sure. You won't know if you try, of course

 

[rmccolman]

I measured it, and indeed it is a round 18-incher (well, 18x19-ish, anyway).

Although I'd be interested in re-purposing this old DirecTV dish for FTA (by adding a linear LNB), I don't want to end up with a situation where I get lots of signal breakup anytime there are thicker clouds or a light rain. (I do imagine that any HD channels will be more vulnerable to that than SD channels, since this dish was designed for SD reception.)

Richard

 

[comfortably_numb]

My recommendation would be to spend $100 and get a "real" FTA dish (90cm).

 

[Inclined Orbit]

I don't think its worth bothering with. The 18" dish was designed for 9 degree DBS Ku satellite spacing with very high power satellites. FTA is 2 degree spacing and lower power satellites. If you can find an LNBF that magically lands on the focal point you might get some transponders here and there. But why? 18" dishes are throw away items and a 1m Ku dish that interfaces with common plentiful LNBs and works great is not very much $$.

 

[rmccolman]

This input doesn't surprise me at all. I figured making the dish useful would be a stretch As I said, I just thought I'd double-check.

Thanks - Richard

 

[phlatwound]

A blast from the past...

Dish 300 + DMX521 linear + SG 2100 motor combo

Inspired by recent efforts by turbosat and mikelib I decided to see what I could get with a Dish 300 (18" x 20") oufitted with a WSI DMX521 linear LNBF on a SG2100 motor. Receiver was a Coolsat 6000. First mounted the motor on the pole and installed the dish (with circ LNBF) on the motor. I...

www.satelliteguys.us

 

[rmccolman]

Interesting link, phlatwound. Looks like some impressive performance with a 18x20" dish.

I'm guessing that a really low noise LNB is the key to getting good signal quality numbers on weaker sat signals when mounted on a small dish.) I still see a few eBay sellers with the DMX521.

Since my old DirecTV dish doesn't take up a lot of storage room, I don't feel compelled to trash it quite yet. Maybe a low-noise LNB mounted on it would be worth some experimentation.

Richard

 

[comfortably_numb]

Interesting link, phlatwound. Looks like some impressive performance with a 18x20" dish.

That was 12 years ago, when everything was modulated as DVB-S. Now, (almost) everything is DVB-S2 or higher. This requires a larger dish.

 

[phlatwound]

Interesting link, phlatwound. Looks like some impressive performance with a 18x20" dish.

I'm guessing that a really low noise LNB is the key to getting good signal quality numbers on weaker sat signals when mounted on a small dish.) I still see a few eBay sellers with the DMX521.

Since my old DirecTV dish doesn't take up a lot of storage room, I don't feel compelled to trash it quite yet. Maybe a low-noise LNB mounted on it would be worth some experimentation.

I wouldn't expect to a "better" LNB to make much difference, the signal types are different now and do require a bigger reflector.

Some of the (quite inexpensive) LNBFs that are available now are superior to anything I was messing with back then, anyway

Thought you might find it interesting to see what we were doing back in the "olden days" with tiny dishes.

 

[rmccolman]

Good insights, guys. (Hey, maybe I'll turn that old DirecTV dish into a solar cooker! )



...or maybe not...

Worth a quick chuckle, anyway.

Richard

 

[Inclined Orbit]

That was 12 years ago, when everything was modulated as DVB-S. Now, (almost) everything is DVB-S2 or higher. This requires a larger dish.

Why would DVB-S2 require a larger dish? With the same modulation and FEC, DVB-S2 provides better performance and receivers will lock at a lower C/N.

 

[Inclined Orbit]

A better LNB won't do much good if adjacent satellites at 2deg spacing are causing interference because the beamwidth of an 18in dish is not good enough for 2deg spacing.

Interesting link, phlatwound. Looks like some impressive performance with a 18x20" dish.

I'm guessing that a really low noise LNB is the key to getting good signal quality numbers on weaker sat signals when mounted on a small dish.) I still see a few eBay sellers with the DMX521.

Since my old DirecTV dish doesn't take up a lot of storage room, I don't feel compelled to trash it quite yet. Maybe a low-noise LNB mounted on it would be worth some experimentation.

Richard

 

[cyberham]

Why would DVB-S2 require a larger dish? With the same modulation and FEC, DVB-S2 provides better performance and receivers will lock at a lower C/N.

This is technically accurate if using the same modulation and FEC. But the reality is that FTA transponders are now prevalent that use DVB-S2 8PSK FEC 3/4 (C/N 7.9 dB) or DVB-S2 8PSK FEC 5/6, for example, (9.4 dB C/N). This is not true exclusively, but you'll miss some good stuff such as some news feeds, NBC, DW, etc. if sticking with tps with lower C/N values.

Among my favourite bookmarked links are these regarding minimum C/N threshold values: click here (DVB-S). and here (DVB-S2).

 

[comfortably_numb]

Why would DVB-S2 require a larger dish? With the same modulation and FEC, DVB-S2 provides better performance and receivers will lock at a lower C/N.

Sorry but that's incorrect. Try receiving DVB-S2 on a DBS dish and see what happens.

 

[Inclined Orbit]

Sorry but that's incorrect. Try receiving DVB-S2 on a DBS dish and see what happens.

With the same modulation (QPSK), data rate and FEC its absolutely true. I can't even count all the on air tests I've performed for DirecTV and other major broadcasters unlinking and downlinking signals and measuring performance of the two standards. May I ask how many times you have done actual on air measurements to back up your claims?

 

[Inclined Orbit]

With the same modulation (QPSK), data rate and FEC its absolutely true. I can't even count all the on air tests I've performed for DirecTV and other major broadcasters unlinking and downlinking signals and measuring performance of the two standards. May I ask how many times you have done actual on air measurements to back up your claims?

Now that I think about it, I was involved in the very first testing DirecTV did using DVB-S2 many years ago and I set up the uplink test transponder on G3C Ku for them to downlink in Las Vegas for a demo.

 

[comfortably_numb]

With the same modulation (QPSK)

I'm not referring to Directv and Dish, which use high powered transponders. I'm referring to common FTA signals. Most now use 8PSK. I have extensive experience (attempting) to receive common S2 signals on small dishes, and I can tell you for a fact you can't tune a common FTA S2 8PSK signal on a DBS dish at this time. At least not within the past 3 years.