23 Jul 2009

SixBox (6m) and FredBox (2m) - /P tests

This evening I managed 16kms contacts with both the SixBox 6m 40mW AM transceiver and with the Fredbox 2m 10mW AM transceiver. QSOs were from Aldreth, Cambs, to Swaffham Prior.

Signals from the SixBox were copied by Andrew G6ALB when I was TXing with a 6m 1/4 wave antenna on a magmount on the car roof. On the superregen RX there was solid copy of G6ALB's 6m AM signal. Andrew uses a Diamond V2000 vertical, which recent discussions have confirmed are NOT as effective as a true 1/2 wave vertical on 6m. Clearly if Andrew had even a 2 el beam the QSO would have been a very decent one.

After finishing on 6m QRP, we moved to 2m AM to try some tests with the 2m Fredbox. A solid QSO was quickly achieved with the 10mW Fredbox using the 6m 1/4 wave antenna on the car magmount. This acts as a 3/4 wave antenna on 2m. I then tried the same antenna on the Fredbox handheld. Again, a solid 2-way QSO at 16kms distance. Switching over to a 1/4 wave whip on the handheld Fredbox resulted in a weaker, but just usable signal and QSO (same signal level as on the 6m SixBox). Finally, I tried the Fredbox handheld with a small helical antenna. Although Andrew could just detect this, no real QSO was possible.

So, with the V2000 in use at the far end of the contact, 40mW AM on 6m was not as strong as 10mW AM on 2m. Notheless, it was fun to give both rigs a portable outing and make some contacts.

The picture shows me during the Fredbox QSO using the 3/4 wave whip on the Fredbox.


g4ilo said...

I just Googled and found your original article about the Fredbox. It looks a very interesting little rig. It was hearing stations on a 2m superregenerative receiver (built from a PW article in the early 1970s) that got me into the hobby - though I'd listened on HF I'd never really had the inclination before to join in.

Perhaps you could interest one of the kit companies to offer the Fredbox as a complete kit? I'm sure a lot of people would then be tempted to build one - I would for sure.

Roger G3XBM said...

It was a simple superregen RX that got me into VHF back in the late 1960s too. The design was the CQ2 in Practical Wireless. I remember hearing a contest station on Snowdon when in a house in Barnsley, Yorks using just the small RX and a 19 inch piece of wire. It was all good fun then, and still is.