Poldhu 5 band Crystal valve Tube Radio with Earpiece DIY KIT
Built and shipped from UK – dispatched air mail within 3 days. This is a kit you will need to solder the components. In valve mode you will need to provide a power supply for the heaters. In other modes the receiver works on 9 volt DC.(pp3) Price includes UK shipping . More pictures to follow.
Price includes Diode tube valve, High impedance crystal earphones, indoor aerial. You will need to provide an earth and aerial for HF and other bands. Normally in powered mode and crystal radio mode just an earth is sufficient for the the AM band.If you want more details please email me.
This radio can work in three modes;
As a Crystal radio. Change the shorting power tab to the crystal position. Select band 2 to start . Fit an earth connection, switch the valve germanium switch to the G position. Turn the RF gain to maximum. Fit the earphones. In this mode you will need to experiment to see of you also need an aerial. In most case some signals should be received with just a good earth connection.
As a powered radio, without the valve in operation Change the shorting tab to the power position. Fit a 9 volt PP3 battery. Switch the V- G switch to the G ( Germanium diode position). Fit an earth and/ or aerial. For the higher frequencies an aerial is recommended. Select the band required and use the main tuning capacitor to select stations. Note about Link A This link removes the main tuning capacitor from the circuit, this enables the X band to be used. With this link removed and the xband tab in position stations can be selected in the VHF band by tuning the small trimming capacitor in band X.
Using the receiver as a pure Valve Radio remove the power tab and fit to the crystal position. Select the V position on the change over switch. Turn the RF gain fully clockwise. Connect a DC 6 volts 300 mA supply to the valve heaters. Frequency selection is the same as other modes.
Price includes tested Diode tube valve;
6H2P-EV / 6X2N-ЕВ Soviet Double Diode HF Tube = EAA91 6AL5 CV283
Any of the above equivalent tubes should work.
Note the chip is out of circuit and the tube is detecting the signal. This is an example of an early radio receiver. Thermionic emissions are taking place and the valve is detection the radio signal. Warning valve may become warm/hot.