PRC-128 (PRC68 Type Radios) External Power Setup

[ke6rwj]

since there really isn't a forum about military radios per-se... (nothing searchable, only "discussion" groups... [which is so 1995] ) .. I wanted to document this project for the masses,
1) because its cool
2) i like to hear myself talk
3) my therapist says its best for my marriage...

I have a couple of the PRC68 style hand held military radios. This one is the PRC-128 and is a 6 meter 30-88mhz or a 2 meter 130-174 mhz radio (its widebanded, dont get excited HAM's). Its battery operated and can use the H-250 mics like the PRC77 and Rt524.

View attachment 246772

the only problem with this radio is that batteries are really hard to come by, although Brooke Clarke (PRC68.com) has an adapter to allow them to use alkaline or NICAD, AA or 9v batteries, I wanted the option of a more permanent power situation

if you put power on PIN E of the MIC of this radio and GND to PIN A, you can hook 12 volts to it, the only problem is that now you cant hook a mic up.. So for some time ive wanted to make a cable that allowed basically an extension of the mic, while inserting 12 volts on those pins...

then one day on EBAY is saw this...

View attachment 246771

its got the normal U-229 (female) like on the H-250, but also the U-228 (male) that makes it more of an extension cable...

this cable shows "MFCS VIC1 intercom cable" not sure what that is for, but i think its for a Missile Fire Control System.. I figure i can cut off the end that has the funny adapter and re-wire it with a cigarette plug...

Here's what i ended up with... and it works GREAT!

View attachment 246773

BTW i recommend these radios if you come across one, they are great, but do some research, they each have their own quirks.. PRC68.com is highly recommended. (The only one that is 100% useful on the ham bands is the PRC-68B BTW)

 

[serial14]

I've always read about those radios, but never felt like I could get enough information to really understand them. I've got a PRC77 and PRC119(1439) and love them. How does the PRC68 compare?

 

[ke6rwj]

I've always read about those radios, but never felt like I could get enough information to really understand them. I've got a PRC77 and PRC119(1439) and love them. How does the PRC68 compare?

There are lots of specific details on the mentioned website PRC68.com, but ill give my opinions..

Here is a nice chart defining the differences in the PRC-68--PRC-128 radios
PRC-68 Family of Radios

1) What was it designed for
I was in the Army and used all three radios in *real* military situations, so i'm a little biased, and like them all.. The PRC-128 was designed for use by Airforce SP's not combat, although ive seen them used in many situations other than just MP type work. These little radios were not really designed for combat, so little things like they "beep", (which you cannot shut off) when the battery is low or the antenna is not matched... the PRC 77 and RT1439 are combat quiet. not a biggie for us, but a difference none the less.


2) Size
The first obvious thing i like is that it is small, very small, (not cellphone small though!) the carry bag can be clipped directly to an LBE belt and your off. its a little too large to stuff in a normal pocket, but cargo pants pockets are perfect.. The PRC77 and RT-1739 are much larger and heavier so they need to be in a pack or a mount. I wouldn't grab my PRC77 to go walking around the flea market, but i would the PRC-128.

3) Freq Capabilities
It has 10 "channels" that can be programed in the field, IE you dont just turn the dial, you have to enter the numbers in a series of button pushes. Depending on the model PRC-68 ---> PRC-128 you get a range of steps (IE freqs as channels) to use. The PRC-68 --> PRC-128 have varying 6 meter (30-88Mhz) or 2 meter (138-174mhz) ranges, so they have a wide range of compatible freqs.. although none can do both at the same time, you have to change an internal part to select which one.. a simple process that requires only a screwdriver. The PRC77 and RT-1439 are 6 meter only in 50 khz steps, although the RT-1439 can do a little better with an offset.

4) Power output
The PRC-128 is 1 watt and the PRC-77 is ~2 watts, The RT-1439 is 4 watts, these power levels really don't matter that much, its the antenna that counts in the end. they all can be installed in some sort of vehicle mounting to allow putting an AMP on them.



In the end the decision is really based on what you like, if you have little space, the PRC-68 --> PRC-128 series radios can be installed in a much smaller space, and will work just fine, if not better that a "stock" PRC-77 or PRC-1439..


For me i have 2 - PRC-77 and, have had RT-1439 in the past, to me its just another option i have to use. I leave the PRC77 in the tent, the RT-524 in the truck and take the PRC-128 when im walking around... I have lots of different military radios, this is my favorite by far and gets used the most.

If you get the opportunity to buy a PRC-68B and your a HAM, snap it up, they will work great on the ham bands, 2m or 6m...

View attachment 246863
image credit: PRC68.com

 

[rboltz]

I wanted the option of a more permanent power situation

Search for "murphy's Surplus" and look under US Comm Equipment. There is a mount for these radios that supplys power and allows mobil use.

 

[Rustygears]

I have the prc-68, an rt-1439 and an rt-1523e. They all play well together on 6m ham band but none have the necessary pl tones necessary for repeater access

The prc-68 is a decent radio with direct synth and on-unit freq programming into channel memory. It will do freq splits. Compared to shrink wrap ham radios of today it is a boat anchor!

 

[mutt1966]

Do you remember the sellar on epay that you got the cable from. Thanks Scott

 

[ke6rwj]

Do you remember the sellar on epay that you got the cable from. Thanks Scott

bronco_buddy, but they dont have anymore, they are local to me and when i went to pick it up, they said it was the only one they ever saw...

it can be made simply enough, both the connectors are available. i have several connectors, just didn't want to go though the trouble. The female connector is on any old mic, the other you can steal of an old j-box or haney might have them.

 

[ColdWarCanada]

then one day on EBAY is saw this...

View attachment 246771

its got the normal U-229 (female) like on the H-250, but also the U-228 (male) that makes it more of an extension cable...

this cable shows "MFCS VIC1 intercom cable" not sure what that is for, but i think its for a Missile Fire Control System.. I figure i can cut off the end that has the funny adapter and re-wire it with a cigarette plug...

Here's what i ended up with... and it works GREAT!

View attachment 246773

BTW i recommend these radios if you come across one, they are great, but do some research, they each have their own quirks.. PRC68.com is highly recommended. (The only one that is 100% useful on the ham bands is the PRC-68B BTW)

Good solution to a common problem. I would suggest a few improvements. Not sure if the cigarette DC plug has a fuse, but it is good practice to put an in-line fuse to protect the radio in the case of a short.

I would also suggest the use of some Anderson Power Pole connectors on the DC line coming out of the adapter cable. That way you could hook the cable to a small 12 VDC gel cell; a cigarette DC plug; a base power supply or other 12 VDC sources. This is a common practice in the amateur emergency service community. The Anderson Power pole connectors, once installed correctly can only be connected up one way.

Power Pole
Standard Interfaces - Connectors and Wiring

This sort of cable can be easily made up using one male and one female U-229 connector.
U-229 Pin Out


I have the PRC-25 and RT-524 in my 1985 Bombardier Iltis 1/4 ton jeep. I use the PRC-126 when walking around. Works great on 6 metres.

A PRC-68 family radio can be hooked up to a VHF amplifier such as the AM-4477
Range Booster

The amplifier will increase the power to 6 or 30 watts, which is the same as the RT-524 set.

Cheers!
Stuart VE3SMF
Photos Section

 

[BillIdaho]

Very interesting! I have a gaggle of various military radios, and have now started in on military HT's. I just got a PRC-127.
What is the going price for a -128?

My -127 takes an adapter (evidently called a "clamshell") that uses 9 AA rechargables. Isn't there a similar adapter for a -128?

 

[ColdWarCanada]

PRC-127 vs PRC-68 line of radios.

Very interesting! I have a gaggle of various military radios, and have now started in on military HT's. I just got a PRC-127.
What is the going price for a -128?

My -127 takes an adapter (evidently called a "clamshell") that uses 9 AA rechargables. Isn't there a similar adapter for a -128?

The PRC-127 is not in the same "family" as the PRC-68. It is a more modern "non-tactical" radio, in the line of a handi-talkie.... The PRC-127 is designed to use AA batteries in a Clam-Shell battery case.
PRC-127, PRC-127A
PRC-68 Family of Radios

There is an battery adapter for the PRC-68 line of radios produced by Brooke Clarke at www.prc68.com

If I have time over the next week, I will cobble together a DC adapter (with fuse) similar to what was shown at the start of the thread.

I have also made a cloning cable for the PRC-68 (PRC-126) radios. Once you have one radio programmed, you can then use it to clone a second radio with the same frequencies. The directions are at:
PRC-68 Series Squad Radio Cloning Cable

All you really need to make this cloning cable is two U-229 female ends (6 pin). You only use pin A (GND) and D (FILL Data). You do not need six conductor wire, just 2 conductor.

Cheers!
Stuart

 

[ke6rwj]

Good solution to a common problem. I would suggest a few improvements. Not sure if the cigarette DC plug has a fuse, but it is good practice to put an in-line fuse to protect the radio in the case of a short.
[/code]

Yes it does have a fuse

I would also suggest the use of some Anderson Power Pole connectors on the DC line coming out of the adapter cable. That way you could hook the cable to a small 12 VDC gel cell; a cigarette DC plug; a base power supply or other 12 VDC sources. This is a common practice in the amateur emergency service community. The Anderson Power pole connectors, once installed correctly can only be connected up one way.

Power Pole
Standard Interfaces - Connectors and Wiring

Yes i agree

This sort of cable can be easily made up using one male and one female U-229 connector.
U-229 Pin Out

yea, i have the connectors, i was just too busy to do it, then this cable came up and it moved to the top of the list since it was so easy.

I have the PRC-25 and RT-524 in my 1985 Bombardier Iltis 1/4 ton jeep. I use the PRC-126 when walking around. Works great on 6 metres.

A PRC-68 family radio can be hooked up to a VHF amplifier such as the AM-4477
Range Booster

The amplifier will increase the power to 6 or 30 watts, which is the same as the RT-524 set.

Cheers!
Stuart VE3SMF
Photos Section

 

[digitaldust]

Does the 2meter version have offsets .600 and ctcss tone
Thanks

 

[ke6rwj]

Does the 2meter version have offsets .600 and ctcss tone
Thanks

The 2meter version can to do any input and output, but not by defined offset. You have to enter the input freq and the output freq.

no it does not do any CTCSS tones at all.

Also, this radio has wider deviation that a regular ham set, so it might sound funny to some people. The deviation is critical because much of your signal will be outside the passband of the repeater, and it wont key, but i have used it on repeaters that have no tone.

It also is a 12.5 khz step for channels, so you might not be able to get dead on freq with it.

even with all that, i use this radio every day, i love it.

 

[papakb]

Hi Chris, good to see you here and a nice writeup too. BTW, I have plenty of batteries for these radios.

Kurt
KG6KMJ

 

[FKAM]

KE6RWJ
I know this is an old thread but I see you are still out there on other posts. I have a PRC-128, but it has issues, I think. I has a high band RF/IF module but the radio only allows me to enter low band frequencies. From what I have read in the manuals the radio should automatically recognize which module is installed and allow the proper freq's to be entered. Do you know if this is correct? If so, I definitely have problems. Or do you know of a way to switch the way freq's are entered? I didn't read the manual word for word and just focused on the parts that I thought applied. Military manuals always seem to leave me lacking the information I need and I spent 42 years in the Army. Any info you might be able to pass along would be much appreciated.
Thanx
Fred KI7YCK

 

[okto]

KE6RWJ I have a PRC-128, but it has issues, I think. I has a high band RF/IF module but the radio only allows me to enter low band frequencies.

Don’t know if this is the issue, but since the display only shows five digits, low and high frequencies (example: 46.250 MHz and 146.250 MHz) will show up the same.

 

[FKAM]

Don’t know if this is the issue, but since the display only shows five digits, low and high frequencies (example: 46.250 MHz and 146.250 MHz) will show up the same.

okto, Roger that. Had another individual on the G give me the same info a while back. Searched the manuals again and still couldn't find anywhere in them with that piece of info. you'd think it would be a important to point out.
Thanx
Fred KI7YCK

 

[ke6rwj]

KE6RWJ
I know this is an old thread but I see you are still out there on other posts. I have a PRC-128, but it has issues, I think. I has a high band RF/IF module but the radio only allows me to enter low band frequencies. From what I have read in the manuals the radio should automatically recognize which module is installed and allow the proper freq's to be entered. Do you know if this is correct? If so, I definitely have problems. Or do you know of a way to switch the way freq's are entered? I didn't read the manual word for word and just focused on the parts that I thought applied. Military manuals always seem to leave me lacking the information I need and I spent 42 years in the Army. Any info you might be able to pass along would be much appreciated.
Thanx
Fred KI7YCK

Fred,

looks like you got some answers, did it solve your issue? you might also look on my website:

http://radionerds.com/index.php/AN~PRC-128

murphys surplus in california has some parts and a nice OEM power supply. (OF-185)

chris

 

[FKAM]

Thanx Chris,
Your site and PRC68.com have been my "go to first" sites for problems and research.
If your page had the answer, I missed it. I went back to the manual and still couldn't find and mention of how the frequency displays (lacking the first #) on the high band when entering. I have already bought all the OF-185 stuff I could get from MIke. Although I waited a little long and he no longer had the NOS AMP housings, my usual luck. So I'm still looking for that part and the mount.
Thanx
Fred

 

[ke6rwj]

Thanx Chris,
Your site and PRC68.com have been my "go to first" sites for problems and research.
If your page had the answer, I missed it. I went back to the manual and still couldn't find and mention of how the frequency displays (lacking the first #) on the high band when entering. I have already bought all the OF-185 stuff I could get from MIke. Although I waited a little long and he no longer had the NOS AMP housings, my usual luck. So I'm still looking for that part and the mount.
Thanx
Fred

Fred,

Ok , i remember i had the same question about the display and read about the first digit somewhere, don't remember where. I'll add a section to the Wiki page to clarify it for any future users.

I ended up building my own rechargeable battery pack for mine, and its been great.

Regarding the OF-185, i still don't have a mount for the OF-185, been looking for some time, haven't seen them anywhere. I plan on just making a mount for all it at some point.