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Old 9th Nov 2018, 8:51 am   #321
Radio Wrangler
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Default Re: Users of 2 metre Amateur Band?

Dropping CTCSS and reverting to 25kHz channel spacing would bring a lot of equipment back into play and would make amateur radio suddenly cheaper to get into.

12.5kHz was introduced to solve the problem of congestion. The problem is now quite the reverse.

CTCSS was introduced to allow there to be more repeaters in a denser network to handle a greater population of users. Due to lack of users, the repeater groups building and maintaining these machines are strapped for funds and for active bodies to do the work. Usage is very low and the network will inevitably shrink. Even the squeakies seem to have lost interest.

It's time for a new band-plan engineered for current circumstances.

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Old 9th Nov 2018, 9:12 am   #322
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Default Re: Users of 2 metre Amateur Band?

Did anyone notice that 1750Hz access is still permitted? It's just not mandatory, so presumably some / most repeater groups don't bother with it.

Furthermore, according to the RSGB 'rules', CTCSS is only required to get the repeater 'up' initially. It is not necessary to transmit CTCSS continually unless the repeater keeper has specifically asked that it can operate that way.

For the most part, therefore, you should be able to go straight back to anyone who has just called through a repeater as long as you call back before it drops out.

https://www.ukrepeater.net/access.htm
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Old 9th Nov 2018, 10:10 am   #323
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Default Re: Users of 2 metre Amateur Band?

But you won't be able to call. Hanging about for someone else to happen to open the repeater is frustrating.

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Old 9th Nov 2018, 10:19 am   #324
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Default Re: Users of 2 metre Amateur Band?

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Did anyone notice that 1750Hz access is still permitted? It's just not mandatory, so presumably some / most repeater groups don't bother with it.
GB3EV Eden Valley repeater below Cross Fell still has tone access, but you have to speak immediately after dropping the toneburst; you can't just check access by firing tone into it and saying nowt, like you once could on GB3AS when it was located at Caldbeck.

I've room in the TR7500 to build and mount a CTCSS board but it's a 'round tuit' job. A far cry from 'whistling-up' the repeater!
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Old 9th Nov 2018, 12:54 pm   #325
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Default Re: Users of 2 metre Amateur Band?

The Central Scotland F.M group repeaters can be opened using 1750KHz tone. CTCSS can also be used but not needed. Given this, what is the necessity for CTCSS.

The CTCSS, narrow deviation and 12.5K spacing made a lot of equipment obsolete and I'm sure a lot of amateurs would not be keen on re investing.

My pair of 2m rigs (Trio TR-9000 & AKD 2001) fall into the above category. I'm tempted to fit a CTCSS board and change the deviation on the AKD.

We now also have the crazy repeater shifts on 70cm as well, but that's another topic!



On the simplex channels, most people round here seem to stick to the old spacing.
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Old 9th Nov 2018, 2:05 pm   #326
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Default Re: Users of 2 metre Amateur Band?

As already stated, CTCSS allows the user to be selective about which repeater they want to open when two are within earshot. There are parts of the borders where it used to be possible to open both GB3TW (then in north west Durham) and one of the eastern Scottish repeaters if I was not careful.

This is certainly less of a problem since most of the old repeaters were forced to move to inferior sites.

CTCSS is also more or less essential for things like analogue internet gateways where anything received by one gateway is typically retransmitted by every other transceiver in the network, so any sort of random carrier or interference picked up by one gateway has the potential to annoy a lot of people around the world. I can see the sense in requiring continuous CTCSS, if indeed that is the requirement, for access to analogue internet gateways.

I would not do away with CTCSS but I would restore 1750Hz tone access to equal eminence and I have never seen the point of the move to 12.5Khz spacing. As you suggest, I never even think of asking someone to QSY to one of the in-between frequencies on simplex.

Unfortunately there are now quite a few repeaters and gateways on the interleaved frequencies, so all of those would have to change, with all the red tape and expense that would involve, if we reverted back to 25Khz spacing.
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Old 9th Nov 2018, 2:40 pm   #327
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Default Re: Users of 2 metre Amateur Band?

I don't see a problem with CTCSS: surely these days fitting CTCSS to an old radio is probably easier than having to build an old 1750Hz toneburst??

Also, 12.5KHz spacing having become established as the PMR standard in the 1970s, the supply of ex-PMR radios for conversion in the last few decades would have been easier than sticking with 25KHz and having to retro-fit 'wide' filters to these radios? Did Pye ever do a 25KHz MX290 or PFX?

The 2M-converted Westminster I had in my cars the 1980s was a 12.5KHz-filtered 'S' version. I'd wound the deviation up a bit because many repeaters back then would drop you if your signak was underdeviated, but receive-audio from 'wide' stations always sounded a bit rough.


Truth is, converting old PMR gear is no longer the cheap entry to amateur radio given that use of non-type-approved radios is verboten to entry-level licensees.
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Old 9th Nov 2018, 2:59 pm   #328
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Did Pye ever do a 25KHz MX290?
Yes! That's the "AW" version. I have two in my collection, possibly originally from Marine or Coastguard frequencies. They are a great deal rarer than the 12.5Khz filtered versions.
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Old 9th Nov 2018, 4:07 pm   #329
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Default Re: Users of 2 metre Amateur Band?

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I don't see a problem with CTCSS: surely these days fitting CTCSS to an old radio is probably easier than having to build an old 1750Hz toneburst??.
Ah, but you dont NEED a 1750hz tone burst unit...you purse your lips, emit a little whistle and up she comes! Never fails.
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Old 9th Nov 2018, 4:13 pm   #330
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Default Re: Users of 2 metre Amateur Band?

Right,
My mast is up...my aerial works, the preamp is fitted, the SWARpaint has done its job...and I still find myself the loneliest man on the planet.

I discovered a major issue with my 'new' hygain though. Because I have mated old with new and the previous owner fitted a different plug, I can no longer mount the rotator on the mast and fit the plug...it's either or! So, I have to have a new mounting bracket made for the base of the rotator...not a big job but certainly one that now puts it 'at the back of the shed'. I want my life back. I have fitted another lightweight rotator as before...it will prove the point to me whether I am once again committing urine to Aeolus. IF it all works I might commit to a winch up mast and the rotator...if it is still poor...I dunno, maybe move house?

Anyway, IO91cc is now again QRV on 2m. Thanks to all who helped in this gargantuan project!

David
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Old 9th Nov 2018, 4:21 pm   #331
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Default Re: Users of 2 metre Amateur Band?

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Ah, but you dont NEED a 1750hz tone burst unit...you purse your lips, emit a little whistle and up she comes! Never fails.
Alas, some of us are so tone-deaf our attempted whistle could be anywhere between 1 and 2.5KHz and we wouldn't realise it.
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Old 9th Nov 2018, 4:46 pm   #332
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Default Re: Users of 2 metre Amateur Band?

"I don't see a problem with CTCSS: surely these days fitting CTCSS to an old radio is probably easier than having to build an old 1750Hz toneburst??"

Not so - if you fit ctcss, you need a switch to select which tone - or none. Unless you hang it in the mic lead as an external unit and that's messy...

I haven't used our local repeater -or any other- since they went ctcss

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PS ALL welcome to the Poole Radio Society net G4PRS on Mondays at 2000, S3 [145.575] FM
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Old 9th Nov 2018, 6:25 pm   #333
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Default Re: Users of 2 metre Amateur Band?

Richard, it's relatively easy to convert an AKD2001 for sub audible tone use with the eprom kit supplied by Spectrum Communications. It converts the synth to 12.5KHz spacing at the same time, and you will have to turn down the wick for 2.5KHz Tx deviation. I converted mine recently and it works fine. There are a couple of wiring mods to do but it only takes about half an hour to complete. Saves having to mount a separate board inside the rig. I found that my AKD is a bit susceptible to alternator whine when using it on /mobile, but that may just be that my works vehicle has a noisy 12V system.
Alan.

Last edited by Biggles; 9th Nov 2018 at 6:41 pm. Reason: Whoops, the chip is a PIC, not an eprom!
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Old 9th Nov 2018, 6:27 pm   #334
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Default Re: Users of 2 metre Amateur Band?

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"I don't see a problem with CTCSS: surely these days fitting CTCSS to an old radio is probably easier than having to build an old 1750Hz toneburst??"

Not so - if you fit ctcss, you need a switch to select which tone - or none. Unless you hang it in the mic lead as an external unit and that's messy...
I've got a circuit somewhere for a PIC-based generator that does all the CTCSS tones as well as 1750Hz (and 1800Hz which some Continental repeaters used). The tones (and silence) are selected by a single push-to-make switch that cycles through the options - you replace your old toneburst on/off switch with a push-to-make button or a biased toggle-switch.

The biggest problem with CTCSS-ing old radios is working out where to inject the tone; you can't just put it straight into the mic input like a 1750Hz tone because it's not in the communications-audio spectrum and will be eliminated by the audio low-pass-filter (which should remove anything below 300Hz) - best place for injection is after the speech-processor/clipper.

For the likes of the old Pye 290 series apparently the TEDX signalling-board which most of them were supplied with can also be reprogrammed to generate CTCSS.
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Old 9th Nov 2018, 6:43 pm   #335
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Default Re: Users of 2 metre Amateur Band?

Another technique is to inject the sub audible tone into the synth loop so it modulates the Tx. Quite a few commercial PMR rigs do this. The loop would appear to respond well to the low frequency mod.
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Old 11th Nov 2018, 11:47 am   #336
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Default Re: Users of 2 metre Amateur Band?

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Richard, it's relatively easy to convert an AKD2001 for sub audible tone use with the eprom kit supplied by Spectrum Communications. It converts the synth to 12.5KHz spacing at the same time, and you will have to turn down the wick for 2.5KHz Tx deviation. I converted mine recently and it works fine. There are a couple of wiring mods to do but it only takes about half an hour to complete. Saves having to mount a separate board inside the rig. I found that my AKD is a bit susceptible to alternator whine when using it on /mobile, but that may just be that my works vehicle has a noisy 12V system.
Alan.

Cheers Alan

Worth looking into. It's so long ago (20+ years) since I used the AKD mobile, I cannot remember if it suffered from alternator whine. What I do know, is that I cannot have the AKD on whilst I TX on 40m as my TX breaks through on the audio side of the AKD. My Trio is not affected whatsoever.
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Old 11th Nov 2018, 12:58 pm   #337
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Default Re: Users of 2 metre Amateur Band?

"I've got a circuit somewhere for a PIC-based generator that does all the CTCSS tones as well as 1750Hz (and 1800Hz which some Continental repeaters used). The tones (and silence) are selected by a single push-to-make switch that cycles through the options - you replace your old toneburst on/off switch with a push-to-make button or a biased toggle-switch."

Fine, but how do you know what tone you have selected? You need a physical indication...

"The biggest problem with CTCSS-ing old radios is working out where to inject the tone; you can't just put it straight into the mic input like a 1750Hz tone because it's not in the communications-audio spectrum and will be eliminated by the audio low-pass-filter (which should remove anything below 300Hz) - best place for injection is after the speech-processor/clipper.

Good point.

Yet another reason to abandon repeaters...Apathy rules

Another factor that I think is counter productive is the proliferation of commercially sponsored digital modes. There seem to be so many and what do they all do? Apart from sell more rigs?

John

There's a fifth horseman and his name is apathy
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Old 11th Nov 2018, 2:19 pm   #338
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Default Re: Users of 2 metre Amateur Band?

What they do is kill SWLing on vhf. But maybe no one does that anymore anyway.

D
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Old 11th Nov 2018, 5:50 pm   #339
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Default Re: Users of 2 metre Amateur Band?

Or maybe everyone is SWLing and never transmitting?

I guess apathy wins. I find my amateur radio activity on HF.

David
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Old 12th Nov 2018, 10:45 am   #340
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Default Re: Users of 2 metre Amateur Band?

Quote:
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"I've got a circuit somewhere for a PIC-based generator that does all the CTCSS tones as well as 1750Hz (and 1800Hz which some Continental repeaters used). The tones (and silence) are selected by a single push-to-make switch that cycles through the options - you replace your old toneburst on/off switch with a push-to-make button or a biased toggle-switch."

Fine, but how do you know what tone you have selected? You need a physical indication...
You count the number of times you press the button [it starts at CTCSS-inactive at power-up].

Then you use your memory - just as we did to select a channel using a rotary or thumbwheel-switch in the dark or when the control-box was concealed under the dashboard.

"I want R3 - that's crystalled in channel 4 - and you heard the famous Ledex-rattle from somewhere behind you.
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