Cobra 138XLR Mods and Personal Experience Request uPD858

[Onelasttime]

Ok so I have googled this and have found quite a bit. That said just because it is out in cyberspace does not mean it is worth while.

So I I am definitely a less is more type when it comes to modifications. I have 2 of these now one is like NOS the other one looks like it was road hard and put away wet.

So I plan on going through them and making sure any updates that where issued for these have been performed.

I plan on recapping them as well and giving them an alignment.

I am going to replace the germanium diodes because they stock ones are only 4 years younger than me and I just turned 45! I do not have any Germanium diodes on hand but I do have Si Schocktty(sp) diodes on hand.

I am strongly considering leaving the audio chain mostly intact. I have been told these have clipping/compression installed from the factory. I might like to let a bit more high's pass through and I might like to re-purpose a switch on front so the factory clipping can be defeated at times.

Since I have a ton of Toshiba, Mitsubishi and MOT voltage regulators I will like replace those too.

I was reading this mans page and was looking for other peoples input about his recommendations!

Can this radio do a 4:1 ratio on AM or is it more like 3:1?

Here is the page I am talking about wanting input on! http://unit399.wixsite.com/858ssb

Since these have clipping in them on the audio side from the OEM do they benefit from making the AMC/ALC a tad less aggressive? Some of these older radio's really come alive when you give them a switched AMC/ALC to allow for slow or fast setting depending on what you are trying to do. On that same note some radio's sound terrible when you start messing with the AMC/ALC

I might install a channel king board in the beat up unit. The channel selector is not in great shape and I am not sure I can fix it. If I can not fix the channel selector then I will toss an encoder in it and do a Channel King Board. I do not like encoders and I do not need the extra channels but I also want it to work well. If I do end up doing a Channel King Board than I will install a freq. counter!

Thanks guys! I am looking forward to getting both of these radio's on air. The one that is kind of rough will likely end up in my car and the one that is like NOS will stay in the house.

 

[sonoma]

I have 3 858 washington base radios that were given to me for scrap parts and I did a complete restore of them and would not use any other radio now for a long time base radio. the 858 radio's if done right have the best RX and TX in my opinion. not a big power house like the dual final and amp installed radios of late,

 

[Onelasttime]

I have 3 858 washington base radios that were given to me for scrap parts and I did a complete restore of them and would not use any other radio now for a long time base radio. the 858 radio's if done right have the best RX and TX in my opinion. not a big power house like the dual final and amp installed radios of late,

I did not recall the number you had but I knew you had at least one!

Ya I am not a big power hungry fan in terms of trying to get power out of a radio. It is too easy to build an amp if you need more power. In fact, it is also easy to just buy an amp if you are not up to building one. Not you specifically I mean in general. Even when I was 18 I thought it was kind of silly for people to make a big deal about getting more power out of the radio itself since it takes such a large increase in power to make a difference on the other end that can be noticed on the receive meter.

I blame the Army since I was raised an Army brat. I have always had a bias towards bullet proof durable reliable designs overbuilt by design! I also blame flight school! LOL It is drilled into you every single day that you need to take care of your gear so it can take care of you when things are critical. Machines only have so much life in them and if you use it all up and leave nothing in the tank so to speak when you really need that piece of gear that is when it will break on you. Mission critical gear never breaks in garrison when you are goofing around and training. It is always when things go sideways and you can least afford to have something break that it will break! Kind of like "Murphys Law".

So I am not at all anti-modification I am just very picky about pros and cons of any modification. Anything that negatively impacts durability and reliability is bad in my book! LOL If it infringes on other peoples rights to operate it is bad.


Modifications to things are like consuming junk food, beer or sex all of those things in moderation tend to either be good for you or cause no harm. The second you take any of them to the extreme food, beer and sex start to hurt you and that is when we have a problem. So I like mods when they increase durability and when they make the device function better. I especially do not want to infringe on anyone else's ability to communicate and have fun because I have done something that is very selfish and disruptive to the hobby.

I have heard plenty 858 radio's and used friends before but never owned one. I thought I did then I found out the model (Palomar 500 SSB)I had bought was late model and was not an 858 PLL. I think it has an LC7130 or 7120 in it. I have heard old 858 chassis in stock trim and in various states of modification and to be honest each of them sounded great different but great.

I have to admit I like the way the Cobra 138XLR looks it just has the look of quality and style. Same thing with the early Madisons and Washingtons they just look nice and were well styled. They age well they do not date themselves. You could re-issue the designs today they would still look great.

Even the circuit design could be re-issued today and they would still be at the top of the pile even if built exactly like they where in the late 1970's.

In fact, I have wanted one for over 20 years. I actually have 2 relays for the 858 radio's that I have been sitting on for a long long time just in case I ever got lucky!

You know people that know love these! You seldom see them for sale and often when you do people want top dollar for them. I have been wanting an early President Madison for a long long time so for me these will effectively take the place of a Madison in my radio collections.

The tins on these radios are thick enough that I could hammer nails into wood and not damage the tins! LOL It was overkill the amount of metal they used in the tins! LOL

I am thinking about stripping the tins and copper plating them at home and then sending them out to have some engraving work done. Then polish and clear coat them. I can copper plate at home. I have never seen anyone else do that.

Cheers!

 

[sonoma]

Rabbit ears here on the site rebuilt a 139XLR about the same time I did my washington base radios. he always said he liked his radio after the recap and align.
unit399 has a web page dedicated to the 858 chassis radios. lots of good info for reading also.

 

[jon666]

nice radio had had several of them over the years

 

[Low_Boy]

Hopefully 399 will get back to you. He is a member of this site.

 

[sonoma]

here is unit399's web page for the 858 radio.

http://unit399.wixsite.com/858ssb