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All sorts of interesting stuff about Ham Radio and old gear from Steve G3ZPS, near London in the UK

KW2000B and KW2000E

FEBRUARY 2017 - KW2000E

Never expected to find a rare super clean KW2000E, but I did. At one of my radio clubs a local ham heard me talking about KW equipment..he offered me his KW2000E at no cost as he was preparing to move house..would not take a cent for it..so I made a charity donation for my conscience. I got lucky yet again with a radio that had hardly any marks and had been properly stored for over 20 years. Came complete with PSU and manuals. One day of cleaning pots, switches, valve holders and 'soft start' power up saw it come to life without a hitch.

Initial under chassis inspection revealed a new RS O/P transformer and some obvious resistor changes where the mechanical filter connects to the first RX IF amp (6BA6). I am reluctant to put all the values back to stock in case there are other mods that I have not noticed. The VFO stability is better than my KW2000B (the E takes less time to settle down). Uses a couple of rare tubes that I did not have in stock - 12BZ6 RF amplifier, and ECC85 first RX mixer.

Its a strange radio with a mixture of improvements, poor design choices and cost cutting over the earlier 'B' model - much better front end on RX, 500kHz band sections but the proper tube S meter amplifier of the A and B was left out (although a spare relay cutout can be used to put it back in ).  The rear octal connector for an external VFO (as on the 2000B) is also missing and blanked off. As the E has 500kHz band segments KW could no longer use the broadband first IF of earlier models and had to tune this IF in parallel with the VFO. This meant adding extra gangs to the VFO capacitor which would no longer fit inside the existing box..so the capacitor sticks out the back of the now open VFO in what looks like a horrible bodge. KW had the same issue with the KW202 receiver.

KW never got to grips with a decent 1kHz dial readout either, the 2000E was a step back from the 2000B, and was only graduated every 5kHz. This is a legacy of using a Jackson slow motion drive, Drake and Yaesu sorted this years before by using a bespoke assembly for their VFOs. Quite why KW bothered with a WWV band position is also beyond me..it has a 100kHz calibrator, and with 5kHz readout - its a pointless addition. I have also noticed some spurious signals on receive that are hard to pin down..odd as the mixing scheme is the same as other KWs and they don't have them.

The 'RF Gain' control is another odd part of the design. KW had a lot of overload problems (probably on 40m) on their earlier rigs and to get round it just stuck a 5K pot across the antenna where it goes into the receiver..so not a gain control at all, just a crude variable front end attenuator (the KW202 Receiver has one). Unlike the AGC  gain control of the A and B models, on the 2000E there is no way to manually adjust the RF and IF gain of the receiver at all. Things got so bad that KW offered a 'modification kit' to replace the RF gain control of the 2000B with this front end attenuator. For some inexplicable reason KW never offered metering for either Relative Power Output or ALC even on the 2000E, all the Heathkit, Yaesu and Drake radios have these features..what were they thinking ? I have a copy of the KW (DECCA) Price List dated April 1976 -  the poor old 2000E (priced at £384.75) is in there - but has been crossed out.  Its a real pity that KW couldn't deliver with the E, it was probably conceived as a stop gap until the doomed digital readout KW2000D was developed (only prototypes ever made)... but unfortunately it was too little and too late and signaled the end of all development on KW ham radio gear.

I had trouble with one of the  2 12V 4 Pole Relays in this rig..didn't take long to spot part of the problem..when I removed the cover to clean the contacts the base of the relay had cracked so much it literally fell apart !. The culprit appears to be excessive heat as the relay is close to two very hot parts of the radio..the audio output valve on one side and a large wirewound resistor on the other. It was almost too hot to remove with bare fingers.  I had a spare but have since located a supplier of modern plug in replacements from UK supplier RAPID

Plenty of contacts on 40 and 80 but may need alignment on 20 / 15 / 10m

OCTOBER 2016 - KW 2000B

The 2000B was probably the best seller of the 2000 line for KW, and a large number have survived to this day. The VFO mechanism is a big improvement over the rather odd design in earlier models., ts esay to replace the Jackson slow motion drive as well. The few little circuit tweaks make this a nice rig to use and I often turn it on to listen to the nets on 80m

It took me many months to find a really clean KW 2000B, but one turned up on eBay in October 2016 just a few miles away. The key for me was that the front panel was unmarked  and it looked like it had been owned by a lab. It had BT (UK telephone) stickers on it and had not been bodged, abused or dented..in fact very few marks. It was bought at a general auction a few months before as it looked nice, but its owner couldn't get a sound out of it and asked his mate to sell it. The PSU was also very clean and he said the radio lit up. The main cosmetic damage was to the radio bezel which had been covered with sticky tape to protect it - although it still had some marks. Year unknown...sometime between 1969 and 1973

Once home it was obvious in minutes why the radio made no sound when he plugged it in..The headphone socket had failed internally and left the loudspeaker permanently disconnected...fixed that it came back to life on RX.  All relays came out for cleaning of both the sockets and the actual contacts, bandswitch was cleaned and we held our breath for TX..again no problem and contacts made straight away. The usual resistor suspects were also changed. VFO drift is quite bad on this radio even after an hour warmup. To combat the drift I bought a Cumbria Designs X lock 'Huff n Puff' VFO stabiliser. This is an easy fit as the 'CAL' control input can be used to feed the correction voltage into the VFO.

Fitting the X lock

The X Lock fitted to the KW2000B has stopped the drift in its tracks. The X Lock needs to voltage control the VFO and there are a number of ways this can be achieved. In the 2000B I decided to use one of the varicap diodes already fitted inside the VFO to get the dial calibration correct. My initial implementation meant the disconnection of this 'CAL' input to the VFO (purple wire) and connection of the X Lock directly to this pin. I then re-adjusted the VFO coil to bring the it back to the nearest 100kHz point. There is a slightly better option which I may move to that would allow the CAL control to have a small effect, this sums the 2 DC voltages together with a couple of opamps.  I have been careful to ensure the mod can be reversed without any changes to the radio..should a purist own it in the future. I powered the board from the 12V AC heaters with a single diode and cap to get 14V DC. Look at my video here - Steve's X Lock.

Some FM on the VFO on speech peaks caused the X Lock to drop out on TX. Dale W4OP fitted an X Lock to a 2000B a few years ago and mailed me a couple of mods he carried out. A solid state stabiliser for the 150V to the VFO (using the amazing LR8N3 chip and a TIP50) and simple FET buffer on the VFO output. The FET Buffer cured the FM, but I put the 150V regulator in as well.

It appears that KWs continued and rather baffling use of a valve VFO was a problem for every 2000 transceiver they made. The TX mixer 'pulls' the VFO slightly on transmit, causing it to move frequency a little - and opening the door for a bit of FM !. KW attempted to fix this on the B and E with a small trimpot on the IRT line that was only in circuit on transmit - they recommended listening to the VFO on another gen coverage RX and switching between TX and RX, twiddling it until there was no change in frequency. The FET buffer below appeared to solve this problem on my B and the trimpot could be shorted out.

 

The dreaded Kokusai 455KHz mechanical filter is pretty good, but as with my other KW gear the filter 'drifts' towards the LSB carrier crystal making USB a bit thin sounding. I have some ceramic resonators which make good carrier oscillators than can be moved slightly to solve this issue...The filter drifts because the mechanical element gets clogged with the deteriorating packing foam inside the can (over a period of 45 years it turns to a brown goo!). Cleaning the internal element of these filters is difficult (but not impossible) and normally brings them back to the correct frequency. All in all this radio appears in very good order.

CABINET / BEZEL RE -PAINT

Re-painting can be very daunting, but I enjoy it. For Drake and Heathkit I always use Hammerite - Drake is black and Heathkit is dark green. I am not too much of a purest for the exact colour - you'll never get a perfect match. All my Drakes look as new in satin black, and my little Heathkit looks great in satin dark green. Scratched cases and damaged bezels look dreadful and are easy to bring back to life, only a few days work...come on guys tatty radios look...tatty, give them a proper new life !

KW gear is a little harder as the cabinet and bezel are different colours (like Collins) - the main case colour is close to Ford Polar Grey, the bezel is lighter and Ford Dove Grey is a very good match - I defy anyone to tell the difference!.  I rub down with a light emery paper block soaked in water...and then use 3 light coats of car (automobile) grey primer and then 3 light coats of the top colour..always looks fantastic.

The completed cabinet below shows how good these two colours look