Nice loud signal from Conrad on 1296.167 JT9F-fast this evening
I needed an adjustable stop for repeatable positioning of workpieces in the vise on my mill. I found a couple of ideas on Google Images and decided to have a bash at making something.
6mm HT Allen bolts 40mm long hold the thing very rigid. Five degrees of freedom (six if you count the T nut slide) mean I can set the stop just about anywhere relative to the vice jaws.
Top assembly with 6mm rod made from 316 stainless in an offset hole reamed at the joint of the top two parts. The rod is clamped tight as the bolt is snugged up. That also locks the discs together, and locks the cylindrical milled faces to the ends of the main body.
Silver steel hinge pin and base with cylindrical housings to allow 180 degree rotation and clamping.
The main body, 25 x 20 x 100mm
The main purpose of this piece of tooling is to help position workpieces in the vice when I’m making multiple identical things, so each one will be fixed solidly in the same position in the vice.
I bought a cheap Chinese version of a Noga clamp, with the clever single-knob which tightens all of the axes in one go. OK, it isn’t quite as nice as my actual Noga, but it was one eighth of the price. I needed a base mount to fit it to the T slots in my Bridgeport mill, so I turned up a bit of silver steel, tapped M8 one end and with a single-point turned M12 thread on the other. Also made a collar from 6082 aluminium to stiffen the assembly, and milled and tapped a T nut from a scrap of EN8.
The finished base in use
close-up showing the tapped spigot and T nut
Fitted into the table slot. Flats are 20mm A/F. The silver steel body is inset 4mm into the aluminium disc so it can rotate as it is tightened
Milled aluminium case for my W6PQL 70MHz LPF. Thirty-three threaded holes in all, M3/M4/M5. Connectors are Jyebao, bronze finish. They seem just as good as Amphenol, maybe not quite in the league of Radiall, but entirely OK at these frequencies and 300W or so at 50MHz and 160W at 70MHz. Don’t expect to have any cooling issues at those power levels. The forward and reverse power sensors connect via 3nF 4.2mm feedthru caps.
Teardown of a RADIALL R570152010 12V latching coax relay. I am trying to fit an auxiliary contact or position indicator to allow my sequencer to know the current state of the relay. The relay has 80dB isolation and handles 500W at 1.3GHz.
The controller PCB is double-sided and contains protection diodes and (possibly) pulsed drivers, not checked that yet.
That projecting pin looks like it would operate an aux contact. Perhaps I could use it to run a Hall sensor, or some contacts cannibalised from a small DC relay.
I have an offset dish which has an f/d around 0.6, so I decided to make one of Jeffrey Pawlan WA6KBL’s linear dual-mode feedhorns as published in DUBUS 2016/1. The design uses a stepped horn and an oval iris with direct WR90/WG16 flange connection. The horn and round iris were turned from 65mm diameter aluminium bar, and the oval iris was milled from 10mm flat bar.
I used metric M2.5 capscrews to fix the three sections together, and tapped the waveguide mounts M4.
I found a 3/4 inch end mill in one of my dad’s old toolboxes, so I used it, not realising that he’d modified the grind, and that the sides were not parallel. Took me three wrecked versions of the oval iris to realise what was wrong. Simple enough to fix, I just milled out the waste in 0.5mm steps.
Although the joints appear to be perfect, I think I’ll need to add a bit of protection to prevent water ingress at the interfaces.
I will probably make a polyethylene cap for the end, although building foam was also recommended as a fill, to prevent any chance of condensation from diurnal pumping
Apart from the issues with that end mill, it was a nice straightforward project. Next step is to measure the return loss and then make a mount to replace the LNA collar on the dish mount. Might use a three-rod mount using aluminium tube or stainless steel rod.
Snip from the waterfall on my Elad FDM-DUO. Signal down a bit now, it was 10-15dB louder around 22:45. Transverter converts to 20m, hence 14403 kHz is actually 144.403 MHz
ED1ZAG/B is in IN53RE, NW Spain, north of Santiago di Compostela. 1300km from here.
Audioshows the keying sidebands from the CW and a bit of droop during the long tone at the end of the keying.
Recording in WAV format: