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Old 16th Mar 2024, 3:18 pm   #1
Vintage Engr
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Default KW2000B Transceiver.

Having posted earlier for information on the PSU & various modifications therein, I thanks those who sent me a wealth of information.

I've owned this particular KW2000B for almost 20 years, & have only just got around to restoring it, so very much an overdue project. It's in really good condition, - the transceiver that is, but the PSU beggars belief.
It has been subjected to much modification, some that is fairly well documented, & some that isn't.

There has been an extra mains transformer added for the VFO DC heater mods, and also a 'hand cut' PCB, with a 12v regulator. To accommodate all this, an extra L-shaped chassis has been added on the left hand side (viewed from the front).The additional mains wiring was done in 'just-about-insulated wire, with dreadful soldering & loose strands of wire everywhere. This then made me look more closely at the original mains wiring.

I'm sure that I'm not the first person to raise this issue, concerning the route taken by the mains input, via the internal fuse & then back up & down the multicore via the 16-way Painton connector....

On my unit, the Painton plug shell is left floating. I know that it's 'earthed' to the TXCVR once it is plugged in, but "What if"
Not only is this incredibly dangerous, but the multicore cable use in the original manufacture was never really intended for mains use. I used this type of cable back in the 1970's & there were warnings in various supplier catalogues to that effect, even then.

So, whilst I am tidying up the PSU, I decided that it would be safer, in the 21st Century, to totally disconnect the mains circuitry from the TXCVR umbilical cable, & fit a double-pole mains switch on the power supply unit.
However, I do want to retain as much authenticity as possible, with due regard to safety.

So, if I fit a mains switch to the PSU, I have two options:
1. to fit it at the front, where it will be readily accessible. (But not for the purists!)
or 2. Fit it at the rear, where it will be a pain to get at, but not seen.

I wonder if there are any other KW2000B users on the forum that have done this, & which way did you approach the solution?

David.
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Old 16th Mar 2024, 3:49 pm   #2
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Default Re: Kw2000b

The same issue of mains on the umbilical is known to us Ten-Tec radio owners. KW electronics were Ten-Tec agents in the UK in times past... The general fix is either a switch on the power supply to replace the functionality of the one fed via the umbilical to the main radio, or wiring the mains lead via the fuse direct to the transformer primary and using the switch on your power distribution panel or wall socket to turn it on and off.
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Old 16th Mar 2024, 4:42 pm   #3
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Default Re: Kw2000b

Here's a picture of the PSU as found. A lot of additional not-very-well added modifications.

I think that I may fit a DP switch to the rear of the PSU, & then add relay operated remote switching using the existing pair in the umbilical. That will require just a small standby PSU inside the main one to operate the relay.
At least that won't alter the front panel on the PSU, & the TXCVR power on switch will operate correctly.
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Old 16th Mar 2024, 4:50 pm   #4
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Default Re: Kw2000b

Hi you could retain the switch on the 2000 but wire it to switch a mains relay in the power supply so only 12v on plug in cable no outward mods/holes etc i have done this to both my 2000b and the 2000 Mick crossed posts
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Old 17th Mar 2024, 5:11 pm   #5
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Default Re: KW2000B Transceiver.

I wonder if anyone has a picture if the inside of an unmolested 2000B power supply.
It would be nice to see what it should look like.

Mine has obviously been visited by the late Chas. Miller's 'phantom'...
I shall retain the existing DC heater mod for the VFO etc, but I will have to tidy it up quite a bit.
I'm currently fitting the mains on/off relay arrangement.

Thanks,
David.
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Old 21st Mar 2024, 4:16 pm   #6
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Default Re: KW2000B Transceiver.

Latest update:
I am currently tidying up/ rebuilding the PSU & at the same time adding the mains switch relay etc.
In anticipation of replacing the 100uF capacitors I purchase replacements. By virtue of their old age, I had assumed that it was a good idea from a safety point of view to replace them.

This being based on past experience. I once built a similar HV supply for a transmitter years ago, & it used the capacitors in series, with the balancing/bleeder resistors across each one. I'd used ex-WD capacitors, NOS.

I remember the occasion well, as flushed with success, I went to make a cuppa... Whilst doing so, there was a muffled bang from my workshop, The chassis together with it's huge Parmeko transformer had lifted off the bench, & was now sideways on, with foil & electrolyte everywhere.

So this time instead of going through that again, I went for fresh off-the shelf 105 degree capacitors.
I thought I would check them ESR -wise just for fun. The new miniscule ones read between 0.8 & 0.9 ohms.
All the old ones read 0.34...!
Maybe I should reform the old ones? They are massive, Plessey ones, dated 1970.

Ideas welcome! Tin hats at the ready.

David.
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Old 25th Mar 2024, 6:29 pm   #7
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Default Re: KW2000B Transceiver.

After tidying up the PSU etc, it was time for switch-on....
I ramped up the input voltage slowly over a period of around an hour. No smoke, no bangs. Not bad for something that hasn't been powered up for around 25 years. All HT rails and the stabilized DC VFO heater reading correctly. Winding the Variac up and down the DC heater stayed at exactly 6.34v, so at least that section is now working, which it hadn't been before.

I left the transceiver on the bench, running for a few hours. The idea being that I would do a sensitivity check before carrying out any further work. The receiver seemed to work on all bands, but will obviously need some work to bring it up to useable standards.

Having just gone over to the house for a tea-break, I came back to find it had gone into TX mode... (No mic, no key attached).

I shall now investigate...


David.
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Old 31st Mar 2024, 7:28 pm   #8
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Default Re: KW2000B Transceiver.

After locating the 'auto-transmit' function, this new & obviously unwanted mode had now been cured. There were a number of resistors in the vox/mute/ relay switching circuits that had gone sky high plus electrolytics that were virually open cct.

I was not expecting the receive section to function very well, given the age of the unit. & also the notorious foam-rubber degradation within the Kokusai mechanical filter.
Not currently having any HF antennas in operation, I found an old
'Joymatch Lo Z' antenna tuner, & added a few feet of wire just strung around the workshop.
I couldn't believe what the first results were.
On 10 & 20m, strong signals from just about evrywhere, in fact I got totally distracted from the job in hand!

I shall do a proper sensitivity check later on, but so far, everything looks good.
To be continiued...

David.
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Old 1st Apr 2024, 6:33 pm   #9
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Default Re: KW2000B Transceiver.

Good to hear your KW2000B is receiving well; right now the band conditions on 14-21-28MHz are really rather good - today using my Ten-Tec Corsair [according to the sticker on the bottom was supplied by KW Electronics, who were the UK agents for Ten-Tec in the 70s and 80s so I guess it counts as KW?] I was working stations in Texas, the Caribbean and New Mexico on 10M with it feeding a low-slung dipole.
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Old 2nd Apr 2024, 7:09 pm   #10
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Default Re: KW2000B Transceiver.

Thanks,
I was rather surprised at the first results, as I had reckoned of having to either overhaul or replace the mechanical filter. I am probably at an advantage location-wise, at around 840' ASL...
I remember when KW 2000's came out. I had a friend who built a 'copy', not exactly he used the Collins filter. All the IFT's were old TV ones, stripped from a Plessey chassis & rewound. The cherry on the cake was the cabinet, which was a replica KW, all hand-built.

My friend (G3MZR, now SK) who built the replica had an ex-WD fly press in his basement, & did all the cabinet work with that!
As well as the KW, I've just purchased a Ten-Tec Omni V, which also requires some work, so that will be the next HF project, but some way down the line.

David.

Last edited by Vintage Engr; 2nd Apr 2024 at 7:12 pm. Reason: Typos.
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Old 4th Apr 2024, 4:57 pm   #11
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Default Re: KW2000B Transceiver.

Did you rebuild the filter? I have an A and B 2000 , pretty sure one has filter problems and the other only half the heaters lit.
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Old 10th Apr 2024, 9:12 pm   #12
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Default Re: KW2000B Transceiver.

Quote:
Originally Posted by HamishBoxer View Post
Did you rebuild the filter? I have an A and B 2000 , pretty sure one has filter problems and the other only half the heaters lit.
No, I haven't rebuilt the filter as yet, as the receive section seems to function fairly well. I still have to carry out some sensitivity & alignment checks, so will know then whether there is an excessive loss through the filter.

I managed to obtain a Decca/KW 107 ATU/SWR/dummy load last week, & with the ATU & just 10' of wire in the workshop, I'm still 'pulling in the world' or as one 1950's manufacturer of 1 & 2 valve set kits (HAC) claimed 'Heard All Continents'.
I have now started on the transmitter section, & have got it working on low power/top band into a dummy load.

Have had to take a break due to family comittments, so will resume work on it over the weekend.

I wish you good luck with your 2000's.

David.
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Old 14th Apr 2024, 4:33 pm   #13
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Default Re: KW2000B Transceiver.

Thank you David.
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Old 14th Apr 2024, 8:05 pm   #14
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Default Re: KW2000B Transceiver.

Quote:
Originally Posted by Vintage Engr View Post
Quote:
Originally Posted by HamishBoxer View Post
Did you rebuild the filter? I have an A and B 2000 , pretty sure one has filter problems and the other only half the heaters lit.
No, I haven't rebuilt the filter as yet, as the receive section seems to function fairly well. I still have to carry out some sensitivity & alignment checks, so will know then whether there is an excessive loss through the filter.

I managed to obtain a Decca/KW 107 ATU/SWR/dummy load last week, & with the ATU & just 10' of wire in the workshop, I'm still 'pulling in the world' or as one 1950's manufacturer of 1 & 2 valve set kits (HAC) claimed 'Heard All Continents'.
I have now started on the transmitter section, & have got it working on low power/top band into a dummy

Have had to take a break due to family comittments, so will resume work on it over the weekend.

I wish you good luck with your 2000's.

David.

Good evening, I don’t know if you know but Spectrum Communications have had manufactured a batch of replacement filters for the 2000 series rigs. I haven’t fitted mine yet but others have and they work well.
73, Tim M0AFJ
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Old 15th Apr 2024, 11:57 am   #15
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Default Re: KW2000B Transceiver.

Thanks Tim,
I didn't know that. I have had a look on Spectrum comm's website, & the details are available on request. I will keep this in mind once I've checked out the existing Kokusai filter, - which seems to be working reasonably at the moment.

David.
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