How can I get 5 RF signals into 1? - UK Vintage Radio Repair and Restoration Discussion Forum

Mikey405 · 17th Aug 2008, 3:55 pm

Hi everyone.

Can anyone recommend the best way to combine 2 VHF (Band 1 channels 1 and 4) and 3 UHF (Bands 4 and 5) signals? Is there a 5-in multi-out distribution amplifier that anyone has used (and that isn't astronomically expensive), or would I be best using a 2-way splitter for the VHF and a 3-way splitter for UHF and then feeding them into a 2-in multi-out distribution amplifier.

In either case, can anyone recommend a good unit for the job? I've heard that some distribution amplifiers have a very sharp cut off and won't work with channel 1 on band 1, but anything above is fine.

Thanks everyone.

Kind regards.

From Mike.

Steve_P · 17th Aug 2008, 4:18 pm

From a cable TV point of view, 40 - 45 Mhz is in the return path. So is 61 and 58 Mhz. So we have to be canny.

Contact Taylor Brothers in Oldham : http://www.taylorbros.co.uk/ and the catalogue is on line. Buy a Cable TV amp and reverse path module. Change it so that the Reverse Path and Forward Path go the same way. Job done.

I might have some cable TV stuff here actually.

Cheers,

Steve P.

Mikey405 · 17th Aug 2008, 5:39 pm

Hi Steve.

Thanks for that suggestion although I have to say that it does sound somewhat complicated, still needing splitters and the like.

I was perhaps hoping for something a bit more user-friendly like a Brand-X Model-Y which has 5 inputs and 6 outputs or something similar. If there is no such product then I might try your suggestion though.

Thanks Steve.

Kind regards.

From Mike.

John Robson · 17th Aug 2008, 6:53 pm

If they are outputs from standard modulators, then you connect
them in series and add attenuators to control the signal level,
althrough this is not ideal, it can still gain reasonable results.

For distribution, then there are plenty of 8 way distribution
amplifiers which will work from 40 MHz up to 800 MHz on Ebay,
some even have VHF and UHF inputs.

Mikey405 · 17th Aug 2008, 6:55 pm

Hi Steve again.

I did have a look at your Taylor Bros. catalogue (after rudely dismissing your idea out of hand)

but I couldn't really find anything suitable.

Most distribution amplifiers seem to have a lower frequency limit of 47MHz, but I found a "Triax-Wolsey" distribution amp on the CPC web site for £22 plus vat which has 8 outputs, 2 inputs, and that works from 40MHz to 230MHz and 470MHz to 860MHz. The datasheet is a little bit confusing, but I think I can get about 10db gain on each output, so if I have a 2-into-1 resistive aerial splitter on each of the inputs then I should still have a good output.

I'll order one and report on my findings.

If anyone is interested, the CPC catalogue page is: http://cpc.farnell.com/AP00719/aeria...u=triax-334038

Thanks Steve and everyone.

Kind regards.

From Mike.

Tazman1966 · 17th Aug 2008, 7:24 pm

Hi Mike.

This is the one that I use in my display area. http://www.grandata.co.uk/product_in...3578d4f78bd58c It is from Grandata of Ruislip, Middlesex. I find it works quite well although combining the VHF and UHF signals loses a bit at VHF although I think that is because of the cheap and nasty "Y" splitter/combiner

. Luckily, the Aurora's output is very strong

!

Cheers Mike,

Tas

Andy Green · 21st Aug 2008, 9:23 pm

CPC do quite a few different line amps with multiple inputs
see http://cpc.farnell.com (site down tonight for maintenance)

llama · 21st Aug 2008, 10:22 pm

Thanks Mike for raising this issue. I think this could become hugely relevant to those of us with home RF distribution systems that can be re-purposed when analogue shuffles off this mortal (UHF) coil.

a) I'd like to combine all my sources that can produce 625 lines and make them available to all receivers.

b) can an ordinary self-scanning reasonably modern TV "find" these "any-old-chanels" that don't have an ID built in?

A channelised combiner at a reasonable price could have a decent market, methinks!
Graham

BGmidsUK · 22nd Aug 2008, 12:48 am

Good point about the cable return path Steve.

TVs (and VCRs/DVD recorders for that matter) will certainly store whatever decent signals they find, however they will only put them in order if an ID is present (i.e. channels 1 to 5). The cable channels and anything coming from modulators appear in whatever order the set finds them.

At one time I had 4 or 5 VCRs daisy-chained, using channels 30 to 40, with no mutual interference problems!

BG

arjoll · 22nd Aug 2008, 2:21 am

You could use this backwards, or if you wanted to split the VHF and UHF use a couple of smaller splitters and one of these.

Here VHF starts at 44 MHz (NZ channel 1) so anything for this market will probably do a reasonable job a bit lower than that. The splitter above is rated 5-900 MHz.

17th Aug 2008, 3:55 pm	#1
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	How can I get 5 RF signals into 1? Hi everyone. Can anyone recommend the best way to combine 2 VHF (Band 1 channels 1 and 4) and 3 UHF (Bands 4 and 5) signals? Is there a 5-in multi-out distribution amplifier that anyone has used (and that isn't astronomically expensive), or would I be best using a 2-way splitter for the VHF and a 3-way splitter for UHF and then feeding them into a 2-in multi-out distribution amplifier. In either case, can anyone recommend a good unit for the job? I've heard that some distribution amplifiers have a very sharp cut off and won't work with channel 1 on band 1, but anything above is fine. Thanks everyone. Kind regards. From Mike. __________________ G7TRF

17th Aug 2008, 4:18 pm	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: How can I get 5 RF signals into 1? From a cable TV point of view, 40 - 45 Mhz is in the return path. So is 61 and 58 Mhz. So we have to be canny. Contact Taylor Brothers in Oldham : http://www.taylorbros.co.uk/ and the catalogue is on line. Buy a Cable TV amp and reverse path module. Change it so that the Reverse Path and Forward Path go the same way. Job done. I might have some cable TV stuff here actually. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

17th Aug 2008, 5:39 pm	#3
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: How can I get 5 RF signals into 1? Hi Steve. Thanks for that suggestion although I have to say that it does sound somewhat complicated, still needing splitters and the like. I was perhaps hoping for something a bit more user-friendly like a Brand-X Model-Y which has 5 inputs and 6 outputs or something similar. If there is no such product then I might try your suggestion though. Thanks Steve. Kind regards. From Mike. __________________ G7TRF

17th Aug 2008, 6:53 pm	#4
John Robson Retired Dormant Member Join Date: Apr 2008 Location: Hertfordshire, UK. Posts: 96	Re: How can I get 5 RF signals into 1? If they are outputs from standard modulators, then you connect them in series and add attenuators to control the signal level, althrough this is not ideal, it can still gain reasonable results. For distribution, then there are plenty of 8 way distribution amplifiers which will work from 40 MHz up to 800 MHz on Ebay, some even have VHF and UHF inputs.

17th Aug 2008, 6:55 pm	#5
Mikey405 Octode Join Date: Jul 2006 Location: Solihull, West Midlands and Beaford, Devon Posts: 1,626	Re: How can I get 5 RF signals into 1? Hi Steve again. I did have a look at your Taylor Bros. catalogue (after rudely dismissing your idea out of hand) but I couldn't really find anything suitable. Most distribution amplifiers seem to have a lower frequency limit of 47MHz, but I found a "Triax-Wolsey" distribution amp on the CPC web site for £22 plus vat which has 8 outputs, 2 inputs, and that works from 40MHz to 230MHz and 470MHz to 860MHz. The datasheet is a little bit confusing, but I think I can get about 10db gain on each output, so if I have a 2-into-1 resistive aerial splitter on each of the inputs then I should still have a good output. I'll order one and report on my findings. If anyone is interested, the CPC catalogue page is: http://cpc.farnell.com/AP00719/aeria...u=triax-334038 Thanks Steve and everyone. Kind regards. From Mike. __________________ G7TRF

17th Aug 2008, 7:24 pm	#6
Tazman1966 Nonode Join Date: May 2006 Location: St Albans, Herts, UK. Posts: 2,193	Re: How can I get 5 RF signals into 1? Hi Mike. This is the one that I use in my display area. http://www.grandata.co.uk/product_in...3578d4f78bd58c It is from Grandata of Ruislip, Middlesex. I find it works quite well although combining the VHF and UHF signals loses a bit at VHF although I think that is because of the cheap and nasty "Y" splitter/combiner. Luckily, the Aurora's output is very strong! Cheers Mike, Tas

21st Aug 2008, 9:23 pm	#7
Andy Green Hexode Join Date: Jan 2005 Location: Waterford, Republic of Ireland Posts: 259	Re: How can I get 5 RF signals into 1? CPC do quite a few different line amps with multiple inputs see http://cpc.farnell.com (site down tonight for maintenance)

21st Aug 2008, 10:22 pm	#8
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: How can I get 5 RF signals into 1? Thanks Mike for raising this issue. I think this could become hugely relevant to those of us with home RF distribution systems that can be re-purposed when analogue shuffles off this mortal (UHF) coil. a) I'd like to combine all my sources that can produce 625 lines and make them available to all receivers. b) can an ordinary self-scanning reasonably modern TV "find" these "any-old-chanels" that don't have an ID built in? A channelised combiner at a reasonable price could have a decent market, methinks! Graham

22nd Aug 2008, 12:48 am	#9
BGmidsUK Retired Dormant Member Join Date: Oct 2007 Location: Leicester, UK. Posts: 809	Re: How can I get 5 RF signals into 1? Good point about the cable return path Steve. TVs (and VCRs/DVD recorders for that matter) will certainly store whatever decent signals they find, however they will only put them in order if an ID is present (i.e. channels 1 to 5). The cable channels and anything coming from modulators appear in whatever order the set finds them. At one time I had 4 or 5 VCRs daisy-chained, using channels 30 to 40, with no mutual interference problems! BG

22nd Aug 2008, 2:21 am	#10
arjoll Dekatron Join Date: May 2006 Location: Invercargill, New Zealand Posts: 3,458	Re: How can I get 5 RF signals into 1? You could use this backwards, or if you wanted to split the VHF and UHF use a couple of smaller splitters and one of these. Here VHF starts at 44 MHz (NZ channel 1) so anything for this market will probably do a reasonable job a bit lower than that. The splitter above is rated 5-900 MHz.