Poldhu 5 band Crystal valve Tube Radio with Earpiece DIY KIT

£22.50

Category:

Description

Buy from eBay

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.

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.


Postage In order to keep the postage to a minimum postage is for untracked unsigned for. I always obtain a certificate of postage for proof of postage and always dispatch within a couple of days. Please leave response so I know you have received the parcel safely. If you require a tracked and signed for parcel I can supply this service for £5 extra please ask for an invoice or add £5 to the postage cost.

 

poldhu 5 band new instructions withbuilt2017

Building the board
Solder R1 10M resistor Brown Black Black Green
Solder R2 82K resistor Grey red black red
Solder R3 ` Resistor Zero ohms single black band
Solder R4 Resistor 100K Brown Black Black Orange
Solder C1, C2 Capacitor 100nF 104 100nF
Solder D1 Diode 1N4001 Black – polarity sensitive follow markings on board
Solder D2 diode Glass yellow and red band germanium diode ( any way around)
Solder IC socket Observe the polarity- follow silkscreen on board
Solder Inductors and x band variable capacitor in a separate bag ;
band 1 inductor 1000uH brown Black Red 423KHZ -1.7MHZ
Band 2 Inductor 470uH Yellow Violet Brown Silver 600KHZ – 3.6MHZ
Band 3 Inductor 100uH Brown Black Brown Silver 1.3MHZ -7.9MHZ
band 4 inductor 4.7UH Yellow Violet Gold Silver 6.1MHZ – 27MHZ
X Band Inductor .39uH Orange White Gold Black 60MHZ -180MHZ
X Band Variable capacitor VC2 2-18pF small variable capacitor
Solder VC2 2-18pF trimmer capacitor ( X band tuning control)
Solder slide switch for valve/ germanium diode changeover switch
Solder VR1 Variable resistor 100K volume control ( fit spindle after build)
Solder 8 sets of two pin header pins 5 bands, 1 link A and 2 for crystal /power
Solder 1 x 4 pin header for amplifier output
Solder 3x Connecting blocks For aerial/earth 9 volt DC supply and valve heaters supply.
Solder 3.5mm phono socket (ensure locating plastic pins are through the locating holes in board )
Solder Main tuning variable capacitor 4-141pF ( remove double sided tape from component first )
Solder VR2 variable resistor 100K RF gain control.
Solder 7 pin valve socket
Fit knobs/ Small grub screw for main tuning capacitor knob.
Fit Chip IC 741 operational amplifier Ensure correct orientation!
Fit Valve/ tube wear protective glovers to protect hands Double Diode Valve PHILIPS JAN 5726
Fit the Battery lead- observing polarity
Modes of operation. Use 3 x shorting tabs provided.
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 cases, 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 brand by tuning the small trimming capacitor Vc2 in band X.
Using the receiver as a Valve Radio ( using heater supply only
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. 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.
Using the radio with an amplifier (supplied separately) The amplifier kit consists of the board, 4 pin jumper cable and speaker. Solder wires to the speaker. Observe the polarity on the speaker is the same as the speaker connections on the board. When plugging in the jumper ensure the orientation is right. Use RED as the Vs+ on the Poldhu and amplifier board. The LED on the amplifier is lit when power applied. When fitting turn amplifier to minimum (Clockwise) and set the volume potentiometer on the Poldhu to 50%. Adjustments can then be made. Usually for weaker signals the amplifier will be at maximum (Fully anti-clockwise. The quality and output from the speaker will be greatly enhanced when mounted in a cabinet. The amplifier can drive a larger speaker if required.
For strong signals to avoid distortion you can fit link to Xtal position. The amplifier is now amplifying directly from the crystal radio.
Earphones Use only the high impedance ceramic crystal earphone provided or similar design. Low impedance types as used in IPods’ etc. will not work. However, the output can be fed to a small mono amplifier if you want to drive a speaker. A four-pin header is fitted so that an external amplifier, can be connected using the same power supply from the board. Please email me if you require a small mono amplifier.

Notes on Building;
1. Before soldering the main tuning Capacitor, remove the paper from the double-sided tape. This will help to support the capacitor before soldering.
2. All the inductors and associated links and trimmer are in a separate bag. The 0.47uH inductor for the x band is the small bodied inductor.
3. Link A should always be fitted for the 4 main bands to work, this is only remove for the UHF X band to work.
4. Some frequency overlap on the bands has be designed to improve the “Power free” operation.
5. The radio will work in all modes except Valve with just a 9-volt DC supply connected.
6. When soldering the earphone socket ensure the two plastic pins on the socket fit into the holes in the board.
7. The IC and the Diode D1 are polarity sensitive. follow the markings on the board. All other components are not polarity sensitive.
On the 4.7uH band – main HF band the receiver will work better without an earth and just an HF aerial. You will always need an earth for valve and Crystal radio operation.
Adjustment of the volume and the RF gain should help to improve selectivity in power mode.
Earphones
Use only the high impedance ceramic crystal earphone provided or similar design

If you need clarity on any points please email me for helptrevorsmith50@hotmail.com

Reviews

There are no reviews yet.

Be the first to review “Poldhu 5 band Crystal valve Tube Radio with Earpiece DIY KIT”

Your email address will not be published. Required fields are marked *