Renovation of two KW Vanguards - December 2016        GM3WOJ

Click here to read about the renovation of a KW Viceroy Mk.II

During 2016 I purchased two KW Vanguards. I really only wanted one, but on the same trip South I bought one in Chard, Somerset and another near Thetford, Norfolk. They are different models, as you will see from the (hastily-taken) photos below. Click on any of these photos to view a higher resolution copy.

Renovation of a early-model Vanguard

I bought this one near Norwich, for £100. I was happy to pay this price because it is obviously an early model, with the original Geloso VFO dial marked in Italian, only one VR150/30 voltage stabiliser and no 6BW6 clamp tube beside the 6146. The 6L6Gs in the modulator were missing, but otherwise it is complete and in better condition than the later-model Vanguard described below.


20th December - more info about this early-model Vanguard soon..... 


Renovation of a later-model Vanguard

This was the one I found in Chard, Somerset. It was on eBay, with a price tag of £60 which I paid. The seller said he had been given it by a friend and had no idea as to whether it was working or not. It looked in pretty rough shape, but I could see its potential!

Here are the faults identified when first looked at - (i) dial cord broken (the tensioning spring had also rusted away and fallen off) (ii) two of the six main HV electrolytics disconnected - with signs of one having burst (iii) C38 and C39, two 0.005µF 800V capacitors (to each end of the modulation xfmr primary) were broken and hanging off (iv) one end of R42 (100k ohm) in the Geloso 4/102 was disconnected for some reason (v) C40/41 (2 x 8µF) was loose and desoldered (vi) one end of the 160m anode coil had desoldered (vii) meter glass pushed in (viii) PA mesh cover missing (ix) transformers fairly rusty and overall a very dirty chassis.

20th December - the photos below show this Vanguard after the initial round of repairs. It delivers about 21W into a dummy load on 80m (with a QV06-20 in the PA) and the VFO is reasonably stable after a warm-up period. There is still work to do - the VFO note is good on 160/80/40m, but poor on 20m and above. Using a Ronette Coronation 53 microphone, the AM sounds good, but is rather too bassy to be effective, so I will try to find a more suitable mic. or look at tailoring the audio in some way. More info. soon...... 


Replacing the broken dial cord of the Geloso 4/102 VFO        

The Geloso 'Signal Shifter' series of VFOs have a simple dial drive mechanism. The front panel 'VFO Tune' knob is connected directly to a 5mm diameter steel shaft which has 3 or 4 turns of the dial cord wound around it (see diagram below) - the dial cord then travels up through a slot at the front of the 4/102 and around a nylon pulley, where it is kept tensioned by a small spring.

There is only a 10-15mm gap between this pulley and the front panel, so replacing the dial cord without some dismantling is not a viable option. My first plan - to remove the VFO unit from the main chassis - turned out to be the wrong one. I desoldered the 11 connections to the feedthroughs on the outside of the Geloso VFO compartment, then realised that the 4/102 is actually quite a small unit (about 5" x 5") and I would need to desolder quite a few more wires within the VFO compartment if I wanted to lift the 4/102 out. This potential desoldering situation was made more complex by the Vanguard having 160m fitted. Luckily I stopped and thought about things (!) and decided that removing the front panel of the Vanguard was a much easier option. As it turned out (Murphy's Law) all of the rusty steel grub screws in the front panel knobs could be loosened, except for one knob. I ended up drilling these grub screws out - a slow tedious task, but it worked. Below is a photo of what a Vanguard looks like without the front panel - you can see the nylon pulley and the broken dial cord, but the tensioning spring had rusted away at one end and fallen off.

More info soon .....