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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 6th Mar 2017, 2:59 am   #161
Damo666
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Default Re: All about CB radio

Hi Jeremy,

I've seen the brown Ceramic filters with 3 legs before now come to think of it, & what you said briefly crossed my mind (thinking it may be a filter), but as you're probably aware by now - my electronic engineering skills aren't the greatest!

I'm off work today, so I'll have a peep inside & report my findings.

Thanks for the input.
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Old 6th Mar 2017, 12:23 pm   #162
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Default Re: All about CB radio

It appears to be a 2 pole crystal filter (taken from Jab Electronic components website):

10M08AA Cent frequ:10.695MHz B/w:8KHz Insert loss:2db Ripple:0.5db
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Old 6th Mar 2017, 7:24 pm   #163
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Originally Posted by Damo666 View Post
PS - The Handheld's are a TRC-1013 & a Harvard 020 2 channel toy type affair.
The 020s aren't quite toys, as they do have multistage transmitters and superhet receivers - they even have a squelch, although it's preset and you can only switch it on and off. I had some surprisingly good distances out of mine given that they just run on PP3 batteries.

Could I ask you a favour - (not urgent and by no means obligatory, but I'd appreciate it if you could) - assuming the aerial is intact, could you measure the exact length (in mm) of the extended aerial from the top of the bottom section to the tip of the aerial, or better still, the length of the entire extended aerial from the bottom of the bottom section to the tip of the aerial (to make that measurement you would have to remove the rear cover).

Shortly after I got mine (in 1981) I loaned it to someone who accidentally snapped the aerial and - meaning well - replaced it with the best match they could find, but the one they fitted was noticeably shorter than the original and they unfortunately did not keep the original one as a reference.

In those days there was no internet so if the local Tandy or local independent electronics shop didn't have what you needed, that was that. Nowadays it's possible to search the whole world for a replacement but I don't know the exact dimensions of the original aerial.
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Old 6th Mar 2017, 9:12 pm   #164
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Hi Sirius,

I only got chance to properly test the Harvard 020 this morning & have only just realised they had a squelch - and the receive sensitivity isn't bad either. I've not done a range check yet, but I'm led to believe they're about 80mW output from the little research I've done.

The antenna on mine is in good order, so absolutely, I'm more than happy to take the rear cover off for you & report the precise length of the antenna, but please hang fire until Wednesday as I'm not home just now.
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Old 6th Mar 2017, 9:30 pm   #165
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Originally Posted by G0HZU_JMR View Post
The 10M08AA is a crystal filter and this would have been used in place of CF101 to improve the 'bleedover' performance of the radio. However, I wouldn't recommend the 10M08AA as it is too narrow and typically gives a harsh sound to the receiver. The 10M15A is a better filter. It looks the same but is wider and doesn't give the harsh sound of the 10M08AA.

The original radio would have used a ceramic filter here at CF101 and this was followed by the MC3357 mixer/FM chip. The ceramic filter was very wide and gave overload/bleedover issues in the MC3357 IF chip, especially when used on UK FM CB when it was busy. My advice would be to check to see if there is a 10M15A filter fitted here or the original ceramic filter.
Hello again, Jeremy.

I got around to opening the Icom this morning, and there's a 10M15AA filter in position CF101 so that's handy.

There's a strange little enclosed red box on the rear inside of the chassis, and I've never seen anything like this before. It connects to the + pin of the power socket, and the remaining terminal goes to an inductor near the usual + entry point on the PCB - so maybe it's a fuse or suppressor of some sort?

There's also a home brew board hanging & uninsulated, and it consists of 2 x HEF40088PB IC's.

I've not really got around to properly describing the fault with the Harvard 407, but when I get chance to, I'll publish another thread so as to avoid detailing this one.

Here are some images of the Icom 1050 guts....
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Old 6th Mar 2017, 9:52 pm   #166
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Default Re: All about CB radio

The "homebrew board" is the bit-of-logic that gives it the repeater-shift.

IMHO the radio's probably worth more as a "10FM-with-repeater-shift" modified version than if it was retroverted back to a boring CB27/81 thing.
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Old 6th Mar 2017, 10:11 pm   #167
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The radio's probably worth more as a "10FM-with-repeater-shift" modified version than if it was retroverted back to a boring CB27/81 thing.
But it would, of course, require an intermediate or full amateur radio licence to be able to be used as it is now.

At one time I would have agreed with you, but activity on the amateur bands generally is so subdued that I'm considering returning several sets in my collection back from 10 metres to their original frequencies.

Damo666, ref: The aerial on the 020, there's absolutely no rush. The radio has had the wrong aerial for about 35+ years now. A little while longer isn't going to hurt.
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Old 7th Mar 2017, 1:55 pm   #168
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I think I'll just leave the Icom as it is & use it for monitoring the said band when conditions are better.

I did a quick Google search for "10M repeaters in the UK" , but no results were reaped - so do they exist over here at all?

Sirius,

No problem at all mate; You've been a great assistance to me, so it's only right I repay the favour. I will definitely get you an answer to your question tomorrow - it's the least I can do.

Anyway, I'll let this thread carry on, so please accept my apologies for the temporary hijacking.

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Old 7th Mar 2017, 8:01 pm   #169
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I did a quick Google search for "10M repeaters in the UK" , but no results were reaped - so do they exist over here at all?
Yes, but not many and some are not what they seem.

Have a look at this page:

https://www.ukrepeater.net/10m.htm

Of those on the map, the two likely to be closest to you are actually beacons, and on frequencies not covered by that Icom.

The one down in Wiltshire is a crossband repeater with its input on 50Mhz and output on 29Mhz, again on a frequency not covered by the Icom.

Only the remaining two (One near Ludlow, one near Northampton) are conventional single band FM repeaters, but both appear to need CTCSS tones to access them, something the Icom probably doesn't have.
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Old 8th Mar 2017, 3:35 am   #170
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Damo666, Re; your concern about whether to post more threads about CB radio repairs:

I think the only thing which would raise concern would be if you started to turn up with a new broken CB radio every couple of weeks or so on a suspiciously regular basis, as it might lead some people to assume that you were using help freely given here to assist you in running a repair-and-sell business.
I personally can't see any problem whatsoever with you starting as many threads as you like on these 'vintage' CB radios. These radios are a legitimate part of radio history and if we were to 'single' these out, then we'd also have to 'single' out all the B40, AR88, DAC90, DAC90A, Pye P75, Dansette record players by the dozen etc. etc., the list goes on and on that get many, and continuous threads posted on their repair and restoration etc.

I think possibly more to the point to be concerned about, is the re-posting of 'long quotes' that I know that the moderators don't like. I don't know if any of you have noticed, but if you've been observant, you will have noticed that some of the 'long quotes' have been removed from this very thread already. I can certainly understand the reasoning that repeating an entire previous post can unnecessarily 'clutter' a thread and make for a lot of scrolling and messing about while trying to read and refer back etc. There may be other reasons as regards to forum space, but I don't know if this is actually a reason or not. At least we don't get the constant repetition of huge pictures being re-quoted again and again like you do on some forums, which can be a real pain.

These are just my observations and thoughts and hopefully I've 'cut down to size' my quote above to include only the relevant part that I was answering, as I've actually had what I'd considered a 'relevant' quote deleted in the past, but when the 'human' element is involved, then it's all down to an individuals opinion in the end. However, I haven't checked lately, but I seem to think that there's something in the 'forum rules' as regards to 'long quotes', as I say, I haven't checked recently, so could be wrong about this.

So to sum up - I would post as many vintage CB radio repair threads as you like as I'm sure that there will be many readers, including me. You only have to look at the amount of 'views' that there have been to this thread in the relatively short time that it's existed to gauge the amount of interest that there is in them.

Last edited by Techman; 8th Mar 2017 at 3:45 am.
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Old 8th Mar 2017, 4:31 am   #171
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I've got quite a bit of catching up to do with this thread and it's a bit late to do it now, but just to say that I remembered after I'd made my last post on the Tristar and the 2SC1969 transistor, that I'd seen that link to Knights and that I was surprised that they had what seems to be the original transistor in stock and at an acceptable price. However, the transistor with the 'label' stuck on was very cheap in comparison and has proved to work extremely well.

I hadn't used the Tristar for a couple of weeks, so got it out from where it had been stored in a cold room and connected it up and as soon as I switched it on a 'whistle' on USB confirmed instant transmission on this mode - something that it wouldn't have done before the transistor was replaced, certainly not from cold. I've been thinking of various reasons why a solid FM carrier rather than SSB would provoke a failing transistor junction into life, but I'm really only guessing.

You need to keep good care of that Tristar box - it may be the only one left in existence! I've done similar things with original boxes for various things and I've recently found a couple of boxes for items that I still have, but have used the boxes for storing odd components or other items.

I've now fitted a crude and dirty power reducer in the Tristar. I had thought about making it very simple and just reduce the basic power to the RF output stage which would affect all modes, but in the end decided to just have it operational on FM only, leaving AM and SSB as they are. It's that FM carrier that's the killer on these sets and may even be what has helped to finish off that output transistor, even though it did eventually fail on SSB. I've reduced the FM output from almost 25 watts to around 6 watts, although I decided to 're-purpose' one of the front panel switches to switch the 'mod' out if necessary for the odd quick emergency power boost for any 'difficult' conditions.

The second pair of transistors arrived the other day and although I resisted the temptation to try to pick the label off the one I fitted in the radio, I may try it on one of the others now I've got several to play with.

Recent new transistors shown below - packet not opened yet, also innards of Tristar:-
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Old 8th Mar 2017, 7:25 pm   #172
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Nice to see those distinctive innards again. What's the extra chip on the channel table eprom board?

Mine was modified that way as well (to add 27/81) but my self-made eprom board only had an eprom and one transistor on it, the transistor being used to provide the necessary ninth bit of the channel code (as it happened, for all channel codes within the range of interest bits 8 and 9 were always in opposite states, so it was possible to derive bit 9 just by inverting bit 8 as it came out of the eprom)

The only thing that ever went wrong with mine was sudden failure of the potted VCO module (the orange thing just north of the eprom board in your image #2) which I thought was going to be a show stopper until I discovered that a little British company called Spectrum Communications made a drop-in replacement. That was many years ago but I believe they are still around and still making various CB and Amateur radio project and accessory kits, and possibly even still making those replacement Cybernet VCOs.

I would have expected you would have implemented lower FM power by running the output stage on the half-supply available from the bottom end of the 'AM Darlington', an option you alluded to in an earlier post.

It seems to have been done both ways in various radios using the 121 chassis (although your radio above uses the 125 chassis) - I can think of at least one model where the FM TX supply came from the (unmodulated) 'AM Darlington' and another where the FM TX supply came straight from the +13V supply, even though both radios used the same chassis.

Sometimes, people would modify the first type to be like the second type, but there was a tendency in those cases for one of the output coils to overheat and the insulation on the winding would break down, shorting the turns. It could be fixed just by taking the old wire off and winding the same number of turns back on with fresh varnished wire of the same gauge, but we never did work out why only the modified radios did this. Radios with the same chassis which had been natively built that way never did it.
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Old 16th Mar 2017, 4:07 pm   #173
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Nice to see those distinctive innards again. What's the extra chip on the channel table eprom board?
I don't actually know. I'm hoping that you or someone else may be able to throw some light on that

Yes, regarding the VCO blocks, it’s said that the ‘orange’ version is better than the older ‘green’ version and is ‘wider banded’. Looking at the circuit of what’s inside them it’s difficult to know why they fail or what part inside them fails as I’ve never cut one open. I’ve certainly found that with fitting various green ones in the same set that they all seem to act a bit differently. I think the replacement VCO may still be available from Spectrum. The FM modification to the ‘059’ main board as used in the Ham-International Multimode 11, Jumbo, Major 588, is to modulate the VCO rather than the band crystals as in the original design. What were the original designers thinking of when they did it that way? I tend to think that the original design of this chassis was probably just AM and SSB only, and that at the last minute just before it was going to go into production, someone from the board room told them that they’d just heard about this ‘new-fangled’ FM that probably wouldn’t catch on, but had to be added to the new radio. It’s the same sort of afterthought that reminds me of the ‘add-on’ extra two speeds that were obviously added to the single speed 78 rpm only record deck by Garrard around 1949/50. Modulating the band crystals like that is a crazy way to do it, as the crystals, particularly when they’re already pulled down off frequency to line up with UK FM, get pulled even further with the lower half cycle of the waveform being severely clipped when they struggle to go any further, hence the Multimode often being affectionately called the ‘Mufflemode’! I do find this effect variable between individual radios and is probably down to individual batches of crystals used. I have to admit that I do sometimes quite like to hear an original, unmodified Multimode type radio, as they definitely have a sound all of their own, although not a good sound to carry over long distances in not so good conditions.

I really don’t know why I don’t do the FM power ‘mod’ by simply taking the feed from the bottom of the Darlington pair, it’s probably just a silly idea that I have that it puts stress on the component, and I just tend to do things the way I always did from back way back when. I probably ought to do it the Darlington way as it’s just a case of basically moving a wire. The way I do it comes from when I used to put ‘super low power’ in these radios. This started when I used to regularly talk to a certain lady who lived quite close and we wanted to make our ‘cosy’ chats as private and undisturbed as possible and I fitted the ‘milliwatt switch’ to her Tristar 747 and my Multimode 11. We would also go in between channels so that we could chat undisturbed on very low power. However, certain locals took great delight in finding us and coming in ‘on the side’ and telling us that they could still hear us and that they were listening! Just thinking about this and how what’s left of CB radio is now just a very ‘male’ dominated thing. Back in the day there were many ‘female’ operators, whereas now the only time you’ll hear a female is when the male operator gets called away for a ‘loo’ break and the female XYL gets to take over for a couple of minutes. There is actually one female station that I hear occasionally within my reception range and although I gather that she’s been around radio for a very long time, she seems to have a serious drink problem and only comes on the radio when she’s very drunk. Although I can get a receivable signal from her station, I can’t honestly understand a word she’s saying and I’ve certainly never attempted to actually speak to her. For a while I thought that she was talking to either someone close to here on a ‘hand held’, or perhaps someone on a very small aerial, but it turns out that she is in fact just talking to herself. She’s only ever on 19 and I’ve never heard her anywhere else. She’s never abusive and it seems that she just talks nonsense in a very quiet and ‘slurred’ voice and seems absolutely oblivious to some of the really terrible abuse that she seems to get from those that live close to her. When she comes on, the outcome is always the same in that she wins and everyone else eventually gives up and switches off – or are forced to move off 19 onto another channel, so perhaps there’s some good coming out of her ‘ramblings' after all. Actually, after not hearing her for quite a long time, I happened to hear her the other day(on 19, of course) and she was actually talking to someone, and I could even understand what she was saying for a change. She was saying that she had stopped drinking and was feeling a lot better in herself. I’ve not heard her since, although I’m only an ‘intermittent’ CB radio user, so I’m only listening occasionally and when I need to catch someone with regards to something in particular or to test out a radio to get some reports on its operation etc. Then there’s the constant and random ‘dead keyer’ on 19 – a ‘known’ old time and old aged, ‘ham’ operator, but that’s another story.

As regards to that coil in the RF output stage burning out and getting shorted turns, I’ve come across this quite a few times over the years. It’s part of a ‘notch’ filter and I think it seems to overheat in sets that have been ‘peaked’ for maximum output, probably when extra bands have been added. I think the ‘slug’ in this coil is best left alone if possible, but it’s likely to have been ‘adjusted’ by someone in most sets that we’re likely to come across these days. It’s a good question as to why it doesn’t burn out in some sets regardless of the output power. It could be that it’s adjusted out of resonance and this causes the overheating, but I’m guessing a bit here. I’ve given my Tristar 777 a bit of stick with its relatively high output power and have been very conscious of that particular inductor, but on checking it, it still looks in perfect ‘unburnt’ condition, but will now be a lot less stressed with the lower FM carrier power. Having said that, I don’t think that my particular radio has ever had its RF output section adjusted in any way during its life, other than me adjusting the bias on the output transistor following its recent replacement. I have to admit to a bodge with burnt and shorted examples of that inductor coil, in that the short can be cleared by carefully separating and slightly spacing out the turns with a very fine jewellers screwdriver, thereby negating the need for a re-wind.

A ‘local’ brought a York JCB 863 (Cybernet 134 chassis) round for me to look at last night. He’d just bought it ‘on-line’ and it was described as fully working, but sold as seen. It had come with no power lead, bracket or microphone, so a good question as to how its previous owner had tested it, although someone had pencilled plus + and – by the power socket on the rear, so may have had a couple of wires connected to it to see it ‘light up’. Apparently, he’d fitted a power lead and connected a power mic, but although the radio worked, he’d been told that the audio output was very quiet. He phoned and asked if he could bring it round on his way to a bikers meet and I said I would have a quick look at it and that he should call in and collect it after the meet if I’d managed to sort it. He had told me that the mic gain control knob on the front of the radio was ‘solid’ and would not turn. I told him not to try to force it and let me have a look at it. I have to admit that I expected to see a right old dog of a radio. When he brought it round, although obviously well used, it wasn’t actually too bad inside and looked original with no signs of any previous work. There was a lot of built up fur and muck around the spindles of all the pots and I suspect it had been in storage in a shed or garage for many years and had perhaps been in a slightly damp atmosphere for a long time. I took the chassis outside and cleaned round all the spindles with an old tooth brush. I have an oil can of red diesel (left over from when I owned a vintage tractor) which I find good for penetrating oil. I put a drop on the shaft joint and with a blade in the slot to stop the splined shaft being crushed by the application of pliers, carefully slightly rocking the spindle from side to side and eventually it started to move. I gave it a small amount of WD40 and once I got full revolution of the shaft I added a drop of oil to the moving joint. So the mic gain control had seized in the low position, and although still a little stiff, at full on setting the radio received glowing reports on the air.

York 863 innards pictured below:-
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Old 16th Mar 2017, 8:39 pm   #174
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I don't actually know. I'm hoping that you or someone else may be able to throw some light on that
Can't help you there, I'm afraid. From your photo it looks as though the legend on the smaller device has been deliberately obscured, or maybe it just has tape stuck over a window? If you can get any information off the chip maybe we can make an educated guess.

Quote:
Originally Posted by Techman
The FM modification to the Ď059í main board as used in the Ham-International Multimode 11, Jumbo, Major 588, is to modulate the VCO rather than the band crystals as in the original design.
Quite a common method - I think I remember doing that swapover on a 'Mufflemode'. Purpose made FM radios not only apply the modulation (deviation) to the VCO but intentionally run the VCO at half TX frequency so that any deviation applied to the VCO is doubled along with the VCO frequency - using that method, you don't have to wiggle the VCO frequency quite as hard as you would otherwise. The same technique works on handhelds which have crystal controlled channels - there the TX crystal is typically run at 1/2 TX and doubled or 1/3 TX and tripled.

Quote:
Originally Posted by Techman
I really donít know why I donít do the FM power Ďmodí by simply taking the feed from the bottom of the Darlington pair, itís probably just a silly idea that I have that it puts stress on the component, and I just tend to do things the way I always did from back way back when. I probably ought to do it the Darlington way as itís just a case of basically moving a wire.
I have to admit that Darlington always seems rather under-heatsinked to me. When operating in AM or FM mode in radios where both modes run on half-supply the Darlington is dissipating roughly the same wattage as the RF output transistor...only the RF output transistor has the benefit of being bolted to the chassis, whereas the Darlington typically has a heatsink hardly any larger than itself. It wouldn't take much to extend the leads of the Darlington to allow it to be mounted on the chassis for heatsinking purposes - I doubt the extended leads would cause any problems because that transistor only handles either steady DC (FM) or audio frequencies (AM).

Quote:
Originally Posted by Techman
We would also go in between channels so that we could chat undisturbed on very low power.
Sounds as though you might have been better off using a pair of Tandy 49Mhz / 50mW walkie talkies - Only problem was, they used the same frequency as just about every analogue baby monitor on sale at the time. So even there you would have had a lot of fascinated listeners.

From your description of the characters around you it sounds as though CB in your area is still frozen somewhere in 1983 - it got like that around here to the point where I just didn't feel the need to be involved in it any more. After a brief revival of interest in the early nineties only to find that the worst aspects of CB still hadn't really gone away I decided, like many others at the time, to move sideways to amateur radio.

In doing so I just caught the tail end of the period when there were still a lot of old-school amateurs who were still quite techy / technically interested, and the repeaters were all still on enormous 900ft broadcast towers as this was before the government sold off all the transmitter sites into private hands, so even a newly licenced class 'B' operator with an ex-PMR handheld or mobile could typically work people in an 80 - 100 mile radius around their local repeater while they looked around for more sophisticated equipment. It was a good time to cross over, before the advent of easy, unrestricted internet communications sent amateur radio into its continuing slow-motion death dive.

That said, I never fell completely out of love with CB sets themselves or the actual idea of CB, which is why I still have most of the radios which I collected throughout the eighties and early nineties.

Quote:
Originally Posted by Techman
A Ďlocalí brought a York JCB 863 (Cybernet 134 chassis) round for me to look at last night.
That's a first for me, I've never heard of the controls seizing like that. The owner is to be commended for not shearing the control shaft off before you had a chance to look at it. I have a nice York 863 in my collection, but I don't have the correct York badged Cybernet coffin microphone for it, something which always irritates me. Nowadays I could probably just pick up any example of a coffin microphone and print a replica York badge for it - just one of many things I never get around to doing.
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Old 16th Mar 2017, 9:36 pm   #175
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Bought myself a Major M588 and a mint condition President Jackson today from a local. I can see myself going crazy collecting these but I must refrain.

The Jackson feels like a solid well built radio, and the internals are completely untouched by the looks of things. The Major M588 is also untouched but only in average condition.

What's everyone's thoughts on these rigs?
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Old 16th Mar 2017, 10:06 pm   #176
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In post 165....

"There's a strange little enclosed red box on the rear inside of the chassis"

That looks exactly like the in-line power lead choke that Philips used to fit externally to their car radios in the 70s. Presumably been purloined from an old car radio to assist with suppression.

Peter.
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Old 16th Mar 2017, 10:11 pm   #177
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Default Re: All about CB radio

Damo, the President may be an original Japanese made Uniden, if it's old enough, and if so, automatically a decent radio. I don't know them well myself.

I'm not a great fan of the M588 as it has one of my least favourite Cybernet chassis (059) in it, mainly due to it having fairly poor FM TX audio as built. As Techman mentioned, though, there is a workaround for that.

Is your location in Lancashire anywhere near Blackpool?

The Blackpool amateur radio rally (At the 'Norbreck Castle' hotel) is coming up in about three weeks (April 9th 2017)- it would be rare not to see a few dilapidated CB radios (and some decent ones) for sale there. The junk (good for harvesting spares from) can usually be found on the stalls and sometimes in cardboard boxes on the floor - radios in better condition tend to be offered in the 'bring and buy' section, although their presence in the bring and buy is no absolute guarantee that they work any better than the ones in the boxes on the floor. If you buy anything there, you have to be prepared for the possibility that you might end up having to fix it, but you seem to enjoy that possibility.
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Old 16th Mar 2017, 10:28 pm   #178
Damo666
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Default Re: All about CB radio

Peter,

That's what I thought it might've been, so thank you for the clarification.

Sirius,

The Jackson says made in the Philippines; The FM power was set at 10W, but I turned it down to 5W to run my amplifier. The SSB power is about 30W, but it's hard to tell exactly as my power meter doesn't have a peak hold function.

I was told that this M588 has got the FM audio mod', and the modulation sounds fine on my other rig when monitored. It only covers up to 27.855 if I recall, so doesn't have the full UK 1 > 40 but not to worry.

I live in about 30 miles away from Blackpool and have been to the Norbreck radio rally, but to be honest I wasn't over keen. The bring & buy was OK though. The stock there seemed to be mainly new HF rigs, Antennas, etc'. I'll give it another try though as it's an excuse to take my toddler to Blackpool.

I really miss the rallies in the 90s with boxes upon boxes of Pye PF1S, Burndept, Philips PFX, etc. I wish I'd filled my boots back then, but only being a teenager back then I barely had any money.
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Old 16th Mar 2017, 11:09 pm   #179
SiriusHardware
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Location: Newcastle, Tyne and Wear, UK.
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Default Re: All about CB radio

Blackpool, like all remaining radio rallies, is a shade of its previously mighty self - not a criticism of the rally itself or its organisers, just a reflection of dying interest in the hobby, less people attending and spending money, therefore less attractive to traders, therefore fewer traders, therefore less to attract people in, and so on. At one time me and a licensed friend used to go to Blackpool every year (from Tyneside) just to go to the rally, but in recent years we have not always gone and when we do, we look for something else to visit on the way back.

That said, Blackpool is still one of the biggest remaining rallies that I am aware of, and I have never not seen at least one or two interesting CB or 10 metre radios there.
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Old 17th Mar 2017, 12:19 am   #180
G0HZU_JMR
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Location: Cheltenham, Gloucestershire, UK.
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Default Re: All about CB radio

The Major 588 was the first multimode export radio I ever got to see and use and I still think it's one of the best looking CB radios ever. However, it does contain the Cybernet 059 board (as used in the early Multimode 2 and the early Jumbo) and behind that purposeful/pretty looking front panel is a fairly grim radio in terms of design integrity. There's lots not to like but these radios did have quite a few happy users back in the day. I'm still smitten with the looks of the Major 588 but I couldn't tolerate using one for long back in the day.

I always thought there were distinct user groups when it came to export radios back in the 80s. The Tristar 747 or Hygain V was the sort of radio that would change hands regularly between 16-20 year olds on a budget who just wanted to try out SSB. These radios earned a poor reputation because a typical owner usually didn't have a suitably rated home PSU for it and they would try out various power mikes and would often suffer various issues with RF in the shack. So they often sounded terrible over the air on SSB. If you then factor in the poor design of these radios wrt internal supply regulation and poor PA biasing then it wasn't uncommon to hear these things sounding like the owner's voice was going through a shredder on SSB transmit.

Next up from these was the Multimode 2 and the Major 588 and the Jumbo. These were older radios but often sounded better on SSB transmit and I think they were more immune to RF pickup and more tolerant of power mikes etc. They were also bought by slightly older users who set their station up better presumably with a decent power supply. But these radios were still awful in my opinion.

Next up from this were the various boards found in radios like the Superstar 2000 or Nato 2000 or Tristar 777. These were better again on SSB but they were bleedover boxes on AM and FM. I disliked all of them but they did tend to attract better operators and suffered less abuse both inside and out.

For me the top SSB radios were the 80Ch Stalker 9 and the 120Ch Cobra 148GTL-DX mk1 and mk2 and these radios were very popular amongst the serious operators on SSB. All these radios had their flaws too but all of them were generally excellent on SSB rx and tx although the receiver front end was quite narrow so the receiver lost quite a bit of gain on the lowest and highest of the 120 channels. They were best on high band and a healthy 148 (or Stalker 9) always sounded glorious on SSB transmit or receive. They were all generally poor on FM though with poor receiver performance on FM and the mk1 148 was also quite grim in terms of audio quality on FM transmit. You can tell by looking at the schematic and the factory mods on the back of the PCB that FM was bodged in a hurry into the mk1.

I don't recall using the Jackson but the receiver design looks odd to me if I look at the schematic. I'm suspicious of the AGC design in this radio. With three filters inside the loop in SSB and AM mode it presumably has a lot of group delay in the overall AGC loop and I suspect that this could cause issues with AGC linearity and stability at some signal levels. I think some of these (slightly) newer Uniden radios had issues like this and there were various fudges to sort out these stability/distortion issues on AM/SSB receive. I suspect that the Jackson is one of the radios that suffers like this unless it has already been modded?
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Last edited by G0HZU_JMR; 17th Mar 2017 at 12:44 am.
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