Friday, February 27, 2015

Anglian 4m Transverter

Having had success with the 2m Anglian I decided it was time to finish its cousin the 4m Anglian Transverter . I also put the tinplate box module  in a cabinet along with the 7W power module mounted on a heatsink on the back panel, using the same metal box from makerbase.co.uk.  A metal chassis plate was needed for the inside of the box to mount the modules on, I found some aluminium sheet on ebay that could be supplied cut to size. Note that as supplied there is a lot of "paint to paint" contact between the metal box parts, so a lot of scraping was done to get "metal to metal" contact to help screening. To further help, a piece of Aluminium angle was mounted between the back panel and the chassis plate (as can be seen in the upper picture:-





The transverter was setup so that 0.5mW from the K3 on 10m produced 6W on 70MHz, which is the ideal drive level for my amplifier which has an internal 3dB Attenuator

Thursday, February 26, 2015

Anglian 2m Transverter

A while ago I populated the pcb for my G4DDK 144MHz Anglian transverter. I finally got round to putting it in the tinplate box and tuned it up. All was well, so I decided to put it in a cabinet along with the 8W power module mounted on a heatsink on the back panel. I found a couple of cheap Metal boxes off makerbase.co.uk A metal plate would be needed for the inside of the box to mount the modules on, I found one off ebay that could be cut to size. Note that as supplied there is a lot of "paint to paint" contact between the metal box parts, so a lot of scraping was done to get "metal to metal" contact to help screening. To further help, a piece of ali angle was mounted between the back panel and the chassis plate (as can be seen in the lower picture:-

To add heat transfer, I wanted to mount the power module directly on the heatsink rather than mount it on the back panel then on the heatsink. To do this I would need to make a rectangular hole in the back panel. Discussing this at the Malvern Radio Club, it was recommended I used a nibbling tool. I found one on the internet for 9.00 shipped. It is a brilliant tool; I can see a lot of use in its future!



As there is no conductivity between the metal parts of the case due to the paint a lot of time was spent removing paint to allow good electrical contact between metal surfaces. I also add a piece of ali angle between the back panel and the chassis plate.

The transverter was setup so that 0.5mW from the K3 on 10m produced 7W on 144MHz, which is the ideal drive level for my amplifier

The 144MHz connectors were spaced to allow an external coaxial relay to be attached with a pair of BNC to BNC male adapters. This allows use with a single antenna feeder if needed. Normally when using a masthead preamp the two connectors are used, eliminating the prospect of transmitting up the back end of the preamp