Just Sharing This Analogue 70MHz IF Loop receiver

[Channel Hopper]

The 102, produced by GRE of Japan for the US/UK market.

Interior

 

[Channel Hopper]

And I was wrong, the Drake ESR250 has no 70MHz loop, the tuner demod is a single canister. It is a clean machine though.

Pictures later, still looking for the 324/3240/325

 

[s-band]

I think I've posted this pic before. @John If you get a 70MHz IF RX, you are welcome to try this 3 BW filter I used to use on the SR4500. The 5500 was never as good as the 4500 with filter for getting stuff out of the noise. Pictures got a bit mangled but at least they were there, not like this digital crap.

View attachment 152236

Just for a laugh, I measured it on a 50R analyser with 75 to 50 minimum loss pads. It's not going to win any prizes but the inductors are not ideal (that's my excuse). I don't remember how I set it up or on what test gear. However, it did the job back in t'day.
9.4MHz, 12.9MHz and 17.3MHz at -3dB points

 

[John]

I think I've posted this pic before. @John If you get a 70MHz IF RX, you are welcome to try this 3 BW filter I used to use on the SR4500. The 5500 was never as good as the 4500 with filter for getting stuff out of the noise. Pictures got a bit mangled but at least they were there, not like this digital crap.

View attachment 152236

Just for a laugh, I measured it on a 50R analyser with 75 to 50 minimum loss pads. It's not going to win any prizes but the inductors are not ideal (that's my excuse). I don't remember how I set it up or on what test gear. However, it did the job back in t'day.
9.4MHz, 12.9MHz and 17.3MHz at -3dB points

Lovely - i'm quite intrigued to see what's inside the variable width and gain controls unit as well when it arrives

 

[Channel Hopper]

And I was wrong, the Drake ESR250 has no 70MHz loop, the tuner demod is a single canister. It is a clean machine though.

Pictures later, still looking for the 324/3240/325

A bit late but here they are. I can't see the tuner model clearly, I may take the lid off later to see if the canister does have a pin output allowing connection to the filter kit.

Note that this is one of the first receivers with a 13/18 V selection for the LNB output, though I suspect the tuner is locked to a max 1750MHz scan.

 

[Channel Hopper]

If it is the one pictured in the receiver then yes.

You should find rubbing the chip surface with methylated spirits brings up the identifying numbers, but I will have an answer mid-week.

And for those still interested (Llew) the NE568 was the chip used in 1991/2, superceded by the SA568/A but they can be substituted with small mods to board components.

Somewhere in the archives I have files of the work on early tuner/demod design with Samsung (a different company to that now in the consumer box business), they were using early Sharp digital tuners with dual saw filter switching (18/27MHz) since it was the easy way to lower SR scanning below 10000. Nobody in the business seemed to be interested since all the bouquets provided for the main operators at the time were 22000 or higher.

How things have changed.

 

[Llew]

And for those still interested (Llew) the NE568 was the chip used in 1991/2, superceded by the SA568/A but they can be substituted with small mods to board components.

Somewhere in the archives I have files of the work on early tuner/demod design with Samsung (a different company to that now in the consumer box business), they were using early Sharp digital tuners with dual saw filter switching (18/27MHz) since it was the easy way to lower SR scanning below 10000. Nobody in the business seemed to be interested since all the bouquets provided for the main operators at the time were 22000 or higher.

How things have changed.

Interesting, thanks. The chip on the board was scraped, so I wasn't able to identify it.

So I assume the IF threshold adjustment in the SR50 is doing the job of an external loop filter?

 

[John]

Interesting, thanks. The chip on the board was scraped, so I wasn't able to identify it.

So I assume the IF threshold adjustment in the SR50 is doing the job of an external loop filter?

It could also be an interesting thing to try on your SR-50 and rout the IF out of the tuner onto the un-used IF loop sockets > through an external 70MHz adjustable filter > returning back to the main board connection as in @s-band's #13 post illustration ?. Also noticed on your receiver pic Llew the mains cable on the cable connection pcb is fused in the neutral with what seems like a solid link on the live
I'm battling with an aquired old Echostar SR-4500 receiver with 70MHz IF Loop at the moment without a User Manual and it's being a pain at the moment learning how to drive the thing - i could come begging soon Llew for the 50 .

 

[Llew]

Also noticed on your receiver pic Llew the mains cable on the cable connection pcb is fused in the neutral with what seems like a solid link on the live

I'll dig it out and check that John.

There's this service manual from the Archive for the SR-4500. Looks to be useful for checking the IF section.

 

[s-band]

@Channel Hopper I presume that the tweaks on your PLL board adjusted the loop filter to optimise the bandwidth for best demod. Does it make much difference if you add extra filtering in that set-up?

@Llew The IF loop is OK on the 4500. The problem is that we can't find a user manual and it's been 30 years since I used one so can't remember how to drive it. The 4500 is unusual, especially by today's standards, as it has set channels that are adjusted for fine tune, polarisation, audio, filters etc, per satellite and per transponder. That made scanning the band time consuming. Once found, the channel could be stored as a favourite.

 

[John]

I'll dig it out and check that John.

There's this service manual from the Archive for the SR-4500. Looks to be useful for checking the IF section.

I'll dig it out and check that John.

There's this service manual from the Archive for the SR-4500. Looks to be useful for checking the IF section.

Thanks for forwarding that Llew, i allready have that file but unfortunately it's the User Manual that's required and is proving to be a right pain to locate one to show how to manually install a new C-band frequency and it's parameters as there does not seem to be any on-screen menu procedure to follow on a monitor unlike the LT8700 models which are perfect but unfortunately do not have the 70MHz IF loop feature.

 

[Manikm909]

I'll dig it out and check that John.

There's this service manual from the Archive for the SR-4500. Looks to be useful for checking the IF section.

looks like u can buy it here -

Echostar SR-4500 / SR4500 manual de servicio/reparación, service manual

Echostar SR-4500 / SR4500 Manual de servicio/reparación, Diagramas esquemáticos.

www.manualzone.com

or maybe SSS have a copy as its in there museum

Museum of vintage satellite receivers. BSB squarial, History of Satellite TV. Chaparral, Echostar, Uniden, Drake

A museum of old satellite receivers with knobs on. Vintage satellite receivers from Rockford, Drake, Satcom, Echostar, RSD. DX Antenna, Connexions and many more. Landmark satellite receivers and the history of satellite TV.

www.satellitemuseum.com

 

[John]

looks like u can buy it here

Echostar SR-4500 / SR4500 manual de servicio/reparación, service manual

Echostar SR-4500 / SR4500 Manual de servicio/reparación, Diagramas esquemáticos.

www.manualzone.com

Appreciate the search but no cigar i'm afraid - they seem to be the Tech Service Manual files as well which does not show how the simple punter (me) to drive the thing when you take it out of the box - these machines are not the easiest to navigate through blind - no on-screen menu to follow etc.

 

[Manikm909]

this 5500 FAQ might help

Echostar SR5500 satellite receiver with internal positioner

Echostar SR5500 satellite receiver with internal positioner

www.your-book.co.uk

 

[Manikm909]

theres also this, depends how close a 5500 is to a 4500

ECHOSTAR SR-5500 Installation And Operation Manuals X3 | eBay

<p>ECHOSTAR SR-5500 Installation And Operation Manuals X3. </p><p>I also have a couple of remotes for these receivers which I can list later.</p>

www.ebay.co.uk

 

[Channel Hopper]

this 5500 FAQ might help

Echostar SR5500 satellite receiver with internal positioner

Echostar SR5500 satellite receiver with internal positioner

www.your-book.co.uk

The SR4500 and 5500 have no common functions at all.

 

[John]

theres also this, depends how close a 5500 is to a 4500

ECHOSTAR SR-5500 Installation And Operation Manuals X3 | eBay

<p>ECHOSTAR SR-5500 Installation And Operation Manuals X3. </p><p>I also have a couple of remotes for these receivers which I can list later.</p>

www.ebay.co.uk

For £12.50 posted they might be worth grabbing for enthusiasts posterity sake, there probably as rare as hens teeth.
Iv'e had a quick run through of the 5500 link but they refer to things such as the 'Enter' button but there is no such thing printed on the SR-4500 remote or receiver either - i'll carry on reading
Edit: Agree with CH post#36.

 

[Manikm909]

Then I would contact the people running that museum thing. Might be able to borrow or scan it for some bucks

 

[John]

Then I would contact the people running that museum thing. Might be able to borrow or scan it for some bucks

Hmmmm, that's given me an idea

 

[Joolz]

Then I would contact the people running that museum thing. Might be able to borrow or scan it for some bucks

This topic caught my eye as I had this variable filter many years ago. I also installed many SR4500 at one point in time so had a look in my collection of old stuff and found this programming crib sheet I used to use. I hope it helps. PS the filters on a Chaparral Cheyanne had a better result.

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