Cobra 148 Resurrection and TX alignment

[@mikesradiorepair]

Ahhh yes the old knob twisting, pot tweaking, coil spreading hack job tune. Looks great on a watt meter but looks like crap on a SA and sounds just as bad on air. In old tube radios it was known as the TVI adjustment which stood for television interference adjustment and many old tube radios had that adjustment accessible from the outside the radio. Interesting point on adjusting bias with the SA. I am all about clean signal output so I may have to start doing that. That was a good 9+ hour rag chew the other day. Thank god for phones with unlimited minutes. :)

[@Mark19960]

+MikesRadioRepair No kidding. Today is my day to play so I have yet another interesting one going up.

[@pwelsheimer]

Mark, looking at the crystal filter (11.325) there are two diodes peeking out from underneath that crystal. The leads to both of them have been clipped - any thoughts on why and should I just reconnect them? This is a Malaysia 148GTL built in Oct 1993 Basically the radio seems to work but not sure of the receive; transmit appears to be good. excellent waveform on the scope and about 4 watts. Thanks for your time.

[@elvisusa.804]

What spectrum analyzer has a vga hook up?

[@kevinrea7820]

Hi. Do you know if the vco replacement Uniden UHIC-070, will work in the 148, the original in mine that needs to be replaced is a IC070.. Thanks, Kevin Lancaster, California

[@Mark19960]

I *think* so.

[@955Indiana]

What's the mic gain pot

[@Mark19960]

Like, whats the value?

[@jaysolomon4156]

Do you do cobra 2000’s I’ve got 3 of them one has the crystal legs eaten off wish I could do a Chanel expansion

[@jackson4861]

are you taking Radio’s right now? I have a 148 that needs a meter.

[@Mark19960]

Not at the moment mate. There are some guys out there that take in this kind of work. However, I may start to do some work because I get asked all the time but it would have to be based on my availability. I would never want someone to send me equipment that I could not service immediately. I just can't do that at the moment and I don't want anyone upset with me because it took too much time. (in my mind, that time is measured in days, not weeks, months, or years.. like we have heard about.. which is a shame.)

[@jackson4861]

@@Mark19960 could you notify me when you could take it ?

[@Nordland796]

How do you connect your multi meter up to this radio to check and set bias ? thanks

[@MrWhizardsLizard]

"It's similar to the "Block Radios", where you remove the block that shorts the test points, except it's wires. Follow the wires from the finals to TP 7- TP8 posts over in the general area of the MB3756 regulator. It's the DC source feed for driver and final. Usually is either brown and green, or green and purple, or purple and brown Some of the newer units have orange and yellow wires, but they all go to the same general location. Just follow instructions for ammeter connection to TP's / adjustment.

[@902Steeler]

What is an affordable spectrum analyzer I can find for alignung my radios? I have a new chinese 148 which is off freq on ssb thank you

[@helijim]

A few years too late but a TinySA. They cost about $60 and double up as a frequency and tone generator. I use one and they're brilliant.

[@charlesgoede2809]

do you work on Alinco DX-70's? thanks

[@1968Bowhunt]

Very informative thanks

[@DAVIDGREGORYKERR]

I am assuming that the Bias should be 0.5-0.6v would I be right, maybe if all of the Citizens Band Transceivers were implemented in DSP hardware and all signal processing done in the digital domain with the firmware in a AES encrypted EEPROM so no tampering can happen is the only way forwards.

[@AURELIOMOREIRAam1960]

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