MOTOROLA P50

J_L_COHEN · Post by **J_L_COHEN** » Sun Nov 23, 2003 2:21 am

hi can any one tell me if this p50 radio is uhf H44GNU3120AN,
and was the p50 seires radio software programed or was it a crystal type radio

thanks jeffrey

Monty · Post by **Monty** » Sun Nov 23, 2003 3:19 am

hi can any one tell me if this p50 radio is uhf H44GNU3120AN, and was the p50 seires radio software programed or was it a crystal type radio

HI:

Indeed, your P50 is UHF, and there should be a
" Sticker " under the Battery telling you what freq
the radio was originally on.

Its also a " PL " radio, and if it has a group of small
swutches, the PL is programmable.

There was a P50 that had a " Programmable "
PL / DPL Signaling feature, but they are somewhat
rare.

They are a nice , small , compact radio, BUT, they are
also [ Crystal Controlled ] and a bit of a job to change
the freq.

It does require a small Test Jig to Realighn the radio
properly. If you want to make the attempt, I am more
than happy to lend some assistance.

Monty

EKLB · Post by **EKLB** » Sun Nov 23, 2003 5:24 am

The Portable that Monty is refering to as to being programable for the PL or DPL was known as the P50 Plus (P50+).

And as Monty has already stated the P50 series radio were all crystal operation and none were programable for freq by rss.

EKLB

J_L_COHEN · Post by **J_L_COHEN** » Sun Nov 23, 2003 11:57 pm

thanks guys, that helped where can i find a pl list for the switches, that will tell me in which position the switch is in equals the pl tone (if that makes sence

)

jeffrey

J_L_COHEN · Post by **J_L_COHEN** » Fri Dec 05, 2003 1:42 am

hi monty,

you stated that you would need a test jig? ok im lost what is this and where can i get one, i need to change the crystals in about 3-4 radios, is that sometihing that i sould be able to do or should i take it to a mrss

thanks jeffrey

Monty · Post by **Monty** » Fri Dec 05, 2003 4:09 am

Hi Jeff:

When changing the Freqs in a P50, although you can
do a " Basic Alighnment " with the Radio powered from
outside the housing, when one places the radio back into
the housing, you will find the Freqs have shifted a bit.

Unless you can place a Jumper on the finger contacts,
you will not be able to enable the radio into a Tx mode.

You can either " Write Down " whet the Freqs are on a
before / after basis, make the changes, then see if you
get close enough once the radio chassis has been placed back
into the Housing OR, what I did is find a Old Radio Housing
( or you can make one from parts ordered from Motorola )
and " Drill Access Holes " in the Back which will alow you to
make what ever adjustments are needed, then just switch
from the Test Housing to the Original.

In other words, there are some slight readjustments
required when the Original Housing is placed on to the
main chassis

This will keep the Transmitt and Receive Freq as close
as possible....

Tech Note:

I use a " Very Small " amount of candle wax to keep the
Cores from Moving once they have been set.

Also,, I would order the " EXACT TUNNING TOOL " to prevent
the Cores from getting Cracked when adjusting

They are very fragile !

Monty

EKLB · Post by **EKLB** » Fri Dec 05, 2003 4:16 am

Hello J_L_COHEN :

The test jig that Montys refering to is probably another radio case that has holes drilled in it in the proper places to gain access to the tuning slugs ect in the radio for setup.

The P50 portable can not be tuned with it removed from the case as it is also seperated from the battery circuit and PL/dpl bd and makes it very tough to tune correctly.

What i have is an old p50 case that i have drilled holes in it to be able to put the P50 radio into for tuning with all the circuits up and running.

I supose if you had a lot of time on your hands you could try tuning and instaling the radio and see if your getting it tuned corectly but ====
TRUST ME- You will learn new cussing words.

And i do have a list of the dip switch codes for the p50 but no way of scanning it.

If youd post here the PL or DPL you need i will look it up on the list and post the info for the sw positions.

EKLB

Monty · Post by **Monty** » Fri Dec 05, 2003 7:42 am

HI:

I may be having a server image issue with AOL users.

Anyhow, this is a 1st generation Jig I made, and do to
the many variations of the P50, I have a " newer version "
that has more holes drilled into it for the different style
boards.

This is just to give a idea of what one can do. As far as I know,
Motorola never made a Service Housing for " All " variations of
the P10 ~ P50

Also, it " Is Possible " to make Receiver Alighnments with
the " Housing Removed " however, you must be able to
solder a wire to the B+ Contact of the radio, or use a
small alligator clip; the chassis is ground, the voltage for
the low power P50 is 7.5VDC.....

Tech Tip:

The Antenna Jack uses a Ultra-Mini Plug.....You can take a ultra-min
plug, solder some RG-174 ( or suitable Teflon Coax ) to the Plug
with a BNC on the other end.

You " MUST " be prepared to " Trim Off" the Ridge of the plug
and remove the shield cover in order for it to fit through the
hole where the antenna screws into the radio " If the Housing
is in place "

Either way, it alows one to tune the Receiver in those boards
which have the tunning cores.....Some later versions were
broad banded, and did not have any major adjustments

For Exploder users:

http://www2.4dcomm.com/metrotech/p50_jig.jpg

Hope the Extra view is helpful
=======================================
=======================================
Although I am NOT CHEAP, I can offer you my services
if you rather not bother....However, it can be a bit pricy
for the Xtals, Support Hardware, and making sure all
the weak spots in the radio are covered.

I do have a number of customers that will sware by
them since they like the small size and light weight.

Some of the Weak Spots of the P50 are as follows:

1. The " Top Plastic " Housing tends to " Break Away " from
the Chassis around where the antenna screws in.

A result of persons pulling on the Antenna...If you hold the
antenna in one hand, and the radio in the other, LIGHTELY
pull on the Antenna.......IF you see the top of the housing
lift up beyond the main housing edge of the radio, the " TOP PLATE " MUST be replaced.

Otherwise, you will have intermittent Tx and Rx

2. The Volume / On-Off Control is another weak spot, and causes
the Power to be low, and also causes the Freq to be unstable.

3. The use of poor grades of " Xtals " can cause your radio to
drift.

4. MAKE sure the Battery area is free can clean of any debrie.
There are NO GASKETS to protect the PL/DPL Board.

5. The " Battery Contacts " on the bottom of the radio ARE
NOT ment to be pulled out. If you do, you MUST replace them
with new contacts.

6. The " Battery Board " uses Double sideded " Masking tape,
and many times, if you remove that board, the tape will have
to be replaced.

So, as you can see, those areas of the radio really need to
be addressed regardless of who installs the Crystals

MS

Post by **wavetar** » Fri Dec 05, 2003 4:23 pm

That's a lot of holes to drill Monty! Must have been a real pain to line them up correctly. I guess I took the 'lazy' way out, I simply cut away the entire front & back from the housing, leaving only the sides & a small bit of each corner. This also enables me to troubleshoot & scope both the audio & main boards while in the case.

Todd

evanh · Post by **evanh** » Sat Dec 06, 2003 10:09 am

where can i find a pl list for the switches

http://www.batlabs.com/p50plus.html

Monty · Post by **Monty** » Sat Dec 06, 2003 2:04 pm

Wavtar Quotes:

That's a lot of holes to drill Monty! Must have been a real pain to line them up correctly. I guess I took the 'lazy' way out, I simply cut away the entire front & back from the housing, leaving only the sides & a small bit of each corner. This also enables me to troubleshoot & scope both the audio & main boards while in the case.

There is one I use that has even more holes drilled
into it to accomodate the other series of radios.

I also have one with the entire back plane removed
( as for trouble-shooting ) as you have indicated, but
( I found ) through my experiencies that when the
entire Back Plane has been removed, the Frequency
shift is noticably higher, which is the reason I chose
the smaller holes.

Nice to have " Both Styles " if required to fix them

If time permits, I will make a " Drill guide " and post it
here for the users. Did not realize others shared the
same headaches in servicing these small portables.

They are nice when they work, and are one of the
more servicable 5 Watt VHF and UHF Portables. Wished
they had a few more channels, but the Compact SP50+
I guess replaced them.....But the SP50's are sorta like
a fat package of smokes

MS