Some old and not so old Transmitters, Transceivers and Accessories
Click on the thumb-nail below to hear another interesting bit of radio history.
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I soon found out why it was not working, someone had tried to repair a fault and had lost some of the parts they had removed. I pulled the bottom off and there was the bottom wafer of the Ledex switch swinging in the breeze. See the fourth photo. I searched the web and from what I found I put it in the too hard basket. This switch has two poles (wafers) to switch the various output filters in between the transmitter PA and the antenna socket. There is also another pole (wafer) that tells the control system the switch has switched in the correct filter for that band. The switch is driven round by what is called a Ledex Switch, a sort of stepping relay that rotates the switch shaft one position at a time.
Had another look at it recently and decided to see What I could do with it. I found some screws that fited the Ledex switch to hold the bottom wafer back on. Put the screws in and powered up the little beast for the first time. The digital dial read 29 MHz and when I rotated the switch the indicated bands changed. Great stuff. The electronics made no attempt to rotate the switch at first.
After a while it tried to shift the switch itself when I rotated it by hand and now when I rotate the band switch it clicks but does not seem to have the power to rotate the wafers. If I rotate it until it stops clicking it settles down on that band and it receives, quite well. Have been using it to listen to the action on 20M during the daylight hours.
The last photo above shows the bottom of the switch and I presume there is a bush missing and perhaps even a bottom support plate. Would anyone be able to take a photo of what it should look like and send to me ?.
It looks as though the Ledex machanism does not have enough power to drive the switch round, I am wondering if it is simply the timing capacitors in a flip flop circuit that determs the drive pulse length ?.
Found another interesting item at the HRSA auction, bought it for $5.00 for the microphone. Now, perhaps I could convert it to a 10M rig ! If you have any information on doing this let me into the secret please. If it helps it uses an MB8719 PLL chip !.
This one had been screwed up and would only operate on low power. Looks like someone has tried to reprogram it to get more channels and had made a mess of it. The CE52E software has allowed me to change that and to correct where the CB channels had been messed up.
Contact me via email at: vk5srp@wia.org.au
You can see how the cam generates SOS three times per revolution. I do not know how it actually workes. It looks to me as though the spring was pre would and turning the handle one revolution started the transmission by setting the cam rotating for one revolution. The tubes are a VR66 as the oscillator and two 807 in parallel in the output.
There are two sets of tubes, one set in use and the other as spares. The power supply has a 12 Volt vibrator "in use" and a spare.
Here is a higher resolution circuit diagram
Does anyone out there know anything about this item ?. I have searched the web and cannot find any information on it.
These two items turned up in a small 19 inch rack with a TCA R5223 communications receiver. I was only interested in the R2553, I helped assemble them as an apprentice at Philips (TCA) almost a life time ago. Looking at the coils it must have been a low band two way radio base station. The crystal in the Transmitter is 8.85 MHz and in the Receiver, 11.2 MHz
I am looking for more definitive information on these.
I asked Ian Wall, founder of Codan, about this item and here is his answer:
Gosh! You are seeking information about a product originally designed in 1972 and up-dated to a Mk2 version and up-dated again to Mk2B so you will understand it is very hard to find anything at all. So far I have found the schematic A3 04-00794 - not the original but a TIFF file created when (I believe) the original paper drawings were abandoned.
It was intended for use with our 100W PEP Transceivers installed on boats/ships and could match the 50 Ohm impedance of the radio to a variety of antennas having different impedances at their feed points. The Load switch SW1 dealt with the resistive component of the antenna by selecting the appropriate winding on T1 whilst the reactive component was handled by the variable inductor L1 and additional inductor L2 or, alternatively, by capacitors selected by Sw2. Resistors R2...R5 are bleeders preventing static build up on the antenna when the series capacitors were selected. The meter measured the antenna current and the knobs were twisted to achieve a maximum reading.
Ian also sent me the circuit diagram. If anyone else can add anymore info, please do.
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Written by and Copyright, Phil. Storr © Last updated 10th May 2012
Not so old Communications Receivers
The BoatAnchor Receiver Collection
The BoatAnchor Outback HF Transceiver Collection
The BoatAnchor Marine HF Transceiver Collection
The BoatAnchor VHF Receivers Collection
The Collection of Two Way Radios
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