Base Bias Tuned VFO

VE7BPO describes the interesting article called Base Bias Tuned VFO. The VFO is based on the common base colpitt's oscillator and tries to change the bias voltage. The 2N3904 transistor is used for the VFO.

I made the VFO with this schematics but the capacitor 220pF is not good for my built VFO. Therefore, the capacitor 220pF and L1 have been changed to make the oscillation. My VFO has got the 7MHz band. Since the VFO is the L/C oscillator, the stability should be managed with the L/C value.

BS170 is used for the QRP rig PA.

The 2N7000 PA was described in my blog message sometime ago. The BS170 by Fairchild can be also used for QRP rig PA. It is N-Channel Enhancement Mode FET. The Maximum Power Dissipation Pd is 830mW, therefore it can be suitable for QRP rig PA. The transmitter section of ADC-40 is the dual BS170 and it generates about 4watts with 13.8V power supply. The small heatsink is required to use BS170s for PA because it will be hot and drops the power. The PFR-3A is the triple BS170 for PA and generates 5 Watts with 12V power supply.

SOTA Halfwave Tuner

The Hendricks QRP Kits has released the SOTA (Summit On The Air) Halfwave Tuner for the backpacker because it is small to put on your bag.  It weighs only 72 grams. This tuner can cover 40m-15m bands for the halfwave length antenna. The SWR LED indicator shows the simple matching for the antenna. It costs $30.00 plus S&H charge.

This is a good combination with the QRP transceiver when you would like to operate the HF bands with the light-weight opration set which consists of the rig, the antenna and the CW key.

SS-40 40m receiver

Recently I got the SS-40 kit which is the 40m superhetro receiver by K8IQY. The sensitivity (MDS) is -132dBm. and the side band rejection is greater than 50dB.
The kit is offered by the Four State QRP Group and the kit price is $55 for the international delivery.

It is definetly a good combination with the QRP transmitter.

KEM-DDS-MINI

Kida Enigneering Manufacture has just released KEM-DDS-MINI which is the DDS-VFO between 1Hz-160MHz.

The price is 6900JPY with LCD and 6400JPY without LCD. You need to add the shipping and handling charge. The AD9953 is the DDS chip.
It consumes 100mA with 5V and you may use this kit for either 2m and 6m transceiver. I would like to get one to build the 6m DSB (Double Side Band) transceiver.