Thursday, August 23, 2012

Cleaning the Cobweb and Playing with the RM's

I’ve still not got round to taking the Cobweb down for its annual service, I guess I’ve been too busy building all the RockMites, but hopefully as this weekend is a UK bank Holiday I shall climb the ladder and remove the Cobweb from the mast and give it a good checking over.
I suspect the wire contacts within the main junction box will need a good clean and probably re-water proofing, also I need to recheck the SWR on some the bands especially on 20 meters as the wire has drooped and stretched from last winter’s gales and the odd bird perching on the antenna.
For a home brew antenna it’s pretty rugged and it does take a beating especially in the winter storms. As it’s been up for two years now without me tinkering it really does need to be just checked over. Hopefully it will require little work and I'm counting on the old adage “if it ain’t broke don’t fix it”!
 I’ve been looking at replacing the inductor L1 in both RockMites with a simple toroid mod which evidently improves power and stability, I’ve never wound a toroid so it’s a first for me, but I need to learn this skill especially if I am going to be buying more kits which will certainly have toroids!
Since my success with the RM20 I have replaced the 2N2222A transistor in the RM40 with the more powerful 2N3053 and also switched R18 to a lower value. Also like the RM20 I soldered in some sockets so that I could swap out components if required. This minor mod should change the power output on the RM40 to approximately a watt. 
I've yet to test though as I thought this wouldn’t take me very long but once the mod had been completed there was silence when I fired up the rig. After much muttering and investigating I traced the problem back to R5 a simple case of one of the potentiometer wires coming loose. which I will resolder as soon as I get the chance.
Finally I've decided to complete the RM collection by purchasing the RockMite 30; well readers must have realised by now, I'm hooked!

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