CB testing this coming week

[Pete Grey]

Thanks for the info LS, very interesting, I look foreword to trying the radio out. It came from a car boot and cost a fiver, the guy said it had been in his loft for 20 years, it looks brand new. If it is ok when it’s powered up I will make up a dipole aerial as in one of your old threads. ln an event it could be a godsend. Once again many thanks.

[Lightspeed]

Pete, a quick low cost test will be to connect the supplied telescopic antenna ( it should have a white plastic cover on the central loading coil if I remember correctly) then power up and press the PTT talk button on the mike. At the same time look at the red LED sinal meters, which should light, showing that the radio is transmitting.

No lights? It could be in battery pack low power consumption mode: This turns off all of the unnecessary illuminations and might also turn the radio to low power. I seem to remember that this light function is controlled by pressing the centre of the channel selector rotary knob.

Little or no signal meter segments lit up on transmit? Possibly the radio is set to 1/2 watt mode. Again from memory, I think there's a toggle switch on the rear to select power. Set it to High and try again.

Hopefully results will be positive and the radio is transmitting OK ( Otherwise new output transistors will need to be fitted by a competent radio engineer.

Check for receive circuit and speaker: Connect antenna and mike as above. Its a speaker mike so the output sound from the radio comes from it. Turn on. Rotate the squelch control fully anticlockwise( Outer ring around channel control knob). Adjust volume control and you should be hearing static from the mike. Rotate the squelch control slowly clockwise; At some point the static noise should be cut. If it passes these tests, you know that its both receiving and transmitting.

Moving on to making an antenna, first thing you'll need will be to purchase or borrow an SWR meter and patch leads. Without this it will be pot luck that your antenna will match your radio. If mismatched it will not damage the receive side of the radio, but transmitting into it could burn out the transmitter output transistor(s).

I recommend a vertical antenna for CB as that's the polarity in greatest use. Either a purchased ready to go silver-rod type antenna or a home made version constructed from a telescopic fishing rod is the way to go. The latter has big advantage of being very covert and ultra portable. If you want to give one a try let me know and I'll give you specifications on what's needed and how to assemble.

[Lightspeed]

BTW Pete, for a fiver its a complete bargain. I'd have snapped it up if I'd seen it.

Even if it needs new output transistors, its still good value, and is an ideal low-cost comms prep.

[Pete Grey]

Thanks LS now I know how to do a proper check on the radio, I’ve a fair bit on my plate at the moment so it will be a couple of weeks, I will let you know how I get on, thanks again.

[Lightspeed]

Sorry Pete. When you wrote that you have no experience of CB. I misunderstood you and read it as no understanding of radio.

27mhz FM gives almost identical performance to 10m band FM operation. That specific radio is well designed, well-made, and easy to operate. The battery pack was its weak feature as rechargeable batteries of the era in which it was made were pretty low capacity.

[Pete Grey]

Hi there LS, I’ve finally got round to testing the cb as you surgested, on transmission red signal lights show on low power but not on high, is that to save battery power?, on receiving everything is fine. So everything looks great, I used new AA batteries to keep unit as original as possible but now will make up a 12v fused lead with battery clips, I will look into getting a better aerial in due course. Many thanks LS for your help and advice.

[Easy rider]

I think your radio is the Midland porta pack 77 805, if you Google midland portapack 77-805d low power out charlie tango dx. It will link you to a question on output. Given in the posts following I'd a pdf download user manual which will help some if it's the radio I suspect.

I have never owned one but a mate did back in the day.

In my units I use varta high energy AA for high drain devices recommended

In the battery compartment if any acid leak on connections springs so on can be removed simply with white vinegar on cotton ear buds it just dissolves it.
Ensure connections are. spotless same with antennas connections .

Ensure antenna is connected before any use and when your transmitting it must be fully extended or you risk blowing tx output.

I know one of the variants with the channel 9 digit printed on front case can be fitted easily with the mid block board expanding channels to 80 total 40 eu and 40 uk handy .

I know it has some sort of power shut down when battery low but not sure what how it effects.

If it's working treat it well ,oil antenna .it's a decent comm ,versatile as it will run off batterys, 12v dc plug in car ,can plug external antenna too magmount or home based even home brew wire like inverted v .
Good find ,great price. Enjoy.

[Pete Grey]

Have downloaded the user manual, thank you Easy Rider and you Lightspeed for all your help.