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.

ALTOIDS PA - CQ Ham Radio - Oct 2009

In the Oct 2009 issue of CQ Ham Radio, JN1GLB, Makoto Kasahara wrote the article of ALTOIDS PA (20w amp for QRP rig in Altoids). It is the same formula with ATS-3B. The article describes that he would make the board with requested people.

The ALTOIDS PA is IRF510 parallel PA with 20w output in HF bands.

KEM-RX3.5 : KEM has been released the 80m receiver.

KEM has released the 80m band receiver (KEM-RX3.5). The receiver is superhetrodyne and IF is 455KHz. It's the same diagram that the 40m band reciever has. The KEM-RX7 for DX orders is $54.87, therefore I assume it will be the same price range.

2W output with 2SC1815 * 4 AMP

JJ1WKN made the 7MHz transceiver and the transmitter generates 2W with four parallel 2SC1815. Here is his blog for 2W transmitter. The schematic diagram of 2W amp is quite simple.

KEM-TRX7-CW video by JQ1BWT

JQ1BWT uploaded the KEM-TRX7-CW video. He compared with his FT-2000d on the video. KEM-TRX has a good performance.

7MHz MicroVert by JA1SCW

This web page describes the MircroVert for the 40m band. The length of the radiator is only 143cm and the length of the coax cable for the counterpoise is 8.3m. You need to attach the 29.4uH coil for the radiator and the choke coil of the FT240-43 between the counterpoise and the coax feed to the transceiver.

The antenna is quite small for 40m band and can install it on the small space. I've made one for my QRP rigs and have a good performance to the domestic CW communication.

Circuit - 7MHz trasmitter - CQ Ham Radio July 2009

You can look at the circuit diagram of 7MHz trasmitter on the July issue of CQ Ham Radio in 2009. The collpits oscillator generates the 7MHz signal and the PA stage increases the RF power to 200mW with 2SC1815GR. The LPF consists of two coils and three capacitors. There is the full break-in capability with 2SA1015GR (PNP transistor) .

The VXO with the 20pF capacitor can move the frequency between 7.000MHz and 7.003MHz.

Parallel 2SC1815GR for 7MHz PA - 500mW

The 7MHz transmitter of the CQ Ham Radio July issue can be upgraded with parallel 2SC1815GR. The orignal PA has only one 2SC1815GR, but JM6QAL has been changed to two 2SC1815GR at PA stage. You can look at the parallel 2SC1815GR which can generate over 430mW although the single one is only 200mW.

I've got one board and made this transmitter with parallel 2SC1815GR. I need to have the receiver that can work with the transmitter.

The 2SC1815 is the typical transistor in Japan. There are sub-alphabet like O, Y, GR, BL for different hfe.

7MHz transmitter - CQ Ham Radio - July 2009

CQ Ham Radio magazine provided the board of 7MHz transmitter at the July 2009 issue. You can get the parts from Marutsu.

Here is the part of 7MHz transmitter that you can buy it here.

The transmitter has 7.000MHz crystal with capacitor, therefore the frequency is shifted to 7.003MHz. The output power is about 200mW. Those two transistors are 2SC1815-BR which are common ones in Japan.

Some of people described that they contacted at the beta version in the magazine. You need to get the receiver to contact. The article shows DE1103 and FT817 for the receiver.

The August 2009 issue shows the 2W amp (2SC2078) for this transmitter.

KEM-RX-HF

The KEM is selling the HF receiver called the KEM-RX-HF for 1.9MH-21MHz. The price is $57.17. The IF frequency is 4MHz and 4-pole crystal filter. The original parts are included for 7MHz/40m band and you can change the frequency with the parts.
Since there is no VFO, you need to get the VFO to generate the signal to convert to IF 4MHz.
I've got the KEM-DDS-VFO to connect the KEM-RX-HF for 7MHz receiver. The price of this VFO is $70.96.

The KEM can accept the DX order on this page. You can pay it via the paypal.

KEM-TRX7-CW

KEM, Kida Engineering Manufacture Inc. has released the 40m transceiver kit the last week. The KEM-TRX7-CW is the 1W CW transceiver with DDS-VFO. The transceiver is super-heterodyne and IF is 4MHz and 400Hz bandwidth with three-pole crystal filter. The price is 11500Yen (about $100). You may buy the 10w linear amp. with two IRF540Ns by KEM.

PFR-3 QRP is ready to order

Hendricks QRP kits has introduced the PFR-3. This three-band portable rig is 5W output for CW operations. You can operate 40, 30 and 20 meters bands. The internal iambic keyer and the balanced line tuner for unbalanced antenna is included.
I've just orderd it for my next portable rig.
It costs $200 for PFR-3 and $40 for the PFR3 paddle. The international shipping and handling cost will be automatically added when you ordered through the paypal.

PFR-3 QRP rig on May 15?

Hendricks radio plans to release the kit called PFR-3. This three band (20, 30 and 40 meters) has 5 watts power at 12V and the portable capability. It is designed by Steve Weber KD1JV. The order will be started around May 15 that is described in the page.

QRP linear amp by KEM

KEM has released the linear amp kit for HF 10W. It calls KEM-LINER-HF. The coverage of the amp is between 3.5-21 MHz but the parts of LPF is only for 7MHz.

The maximum output is 10W and it is enough for QRPers. DC 12V power is needed to run the linear amp and input power is less than 1W. It costs 5500(JPY).

DDS VFO has been released by KEM

KEM (Kida Engineering Manufacture) has released the DDS VFO kit called KEM-DDS-VFO. It will ship from September 4, but they can accept the order of the kit. It costs 5500 Yen/$47.83 ($1=115Yen). The kit main features are DDS-VFO(frequency set by the botton, offset display, multiply display, sweep osciallation, break-in function, RIT, 30 channel memories, port to rotary encoder) and keyer (auto-keyer, straight key operation, side-tone for keyer and port for break-in).
This kit can be connected to KEM-TX7 and KEM-RX7 for the complete 40m QRP transceiver.
It uses AD9834 IC for the main DDS fucntion, therefore you may check the IC data sheet.

Test is completed: KEM DDS VFO

KEM (Kida Engineering Manufacture) has completed the test of DDS VFO. The picture shows the test board with the 40M frequency. They plan to release it around Sep. 4 because they need to prepare the kit manual.

I'd like to get it for my KEM-TX/RX.