Minitor II Frequency...Need Help

Dispatcher85 · Post by **Dispatcher85** » Wed Aug 24, 2005 7:39 am

I have an old minitor II that needs the frequency changed. The minitor was bought off of ebay and the seller did not know the exact frequency but, stated that they thought that it was low band. I took the pager apart, called Motorola and tried to cross ref. the crystal. Motorola told me that they could only tell that it was VHF not sure if it was VHF-high or low band. If someone can help me out these are the numbers listed on the two crytals:

Crystal #1-KXN6300
64300.00
Motorola
F9329

Crystal #2-63960
X6300
T9323

If anyone can help it would be greatly appreciated,
Corey

firegood · Post by **firegood** » Wed Aug 24, 2005 7:57 am

look at the model number of the pager, it will be the 3rd digit.

model number: A0?ZVC2486A
if ? = 1 vhf-lo, 3 vhf-hi, 4 uhf, 5 800-900

Dispatcher85 · Post by **Dispatcher85** » Wed Aug 24, 2005 8:09 am

Thanks for the quick reply. I looked at the bottom of the pager and the id tags are missing off the housing. Is the model number stamped on the pager board anywhere?

Post by **VE9MP** » Wed Aug 24, 2005 8:14 am

You may be able to tell from the part number on the RF board inside ????

Post by **VE9MP** » Wed Aug 24, 2005 8:18 am

I don't have a Minitor II, but I just took apart my Minitor I anbd on the inside is a little piece of metal with the info stamped on it (The Model#, Serial# and Frequency)

Not sure if the II's are the same or not....

firegood · Post by **firegood** » Wed Aug 24, 2005 8:32 am

cant help you on that, ive only got a 4 and a 1. Someone else here might be able to decode the crystals for you.

k2hz · Post by **k2hz** » Wed Aug 24, 2005 9:24 am

I can't find a Minitor II manual but I believe the IF is 17.9 and low band oscillator injection is high side.

If so, 64.300 - 17.900 = 46.400
and 63.960 - 17.900 = 46.060

So, I would guess it is low band 46.40 and 46.06.

CuriousGeorge · Post by **CuriousGeorge** » Wed Aug 24, 2005 6:20 pm

VE9MP wrote:I don't have a Minitor II, but I just took apart my Minitor I anbd on the inside is a little piece of metal with the info stamped on it (The Model#, Serial# and Frequency)

Not sure if the II's are the same or not....

The Minitor IIs have a serial # sticker on one of the boards inside -- no model and frequency info on it but at least a serial #. Of course, that assumes the unit is "whole" and that the sticker didn't fall out during servicing.

MOTO_LR · Post by **MOTO_LR** » Wed Aug 24, 2005 6:59 pm

Corey,

K2HZ is "right on the money".
You do in fact have a Low Band Minitor II, F1 is 46.40 & F2 is 46.06

There should be a small label on the RF Board with the model number of the board. Yours should be a NRB6545A
A NRB6545A is for the 45 to 50 MHz. range.

Is this the frequency range that you need?
If it is not, send me a private message and possibly we can get you
a RF Board for the Low Band range that you need.

Bob, CLARKCOMM

Post by **VE9MP** » Wed Aug 24, 2005 8:16 pm

Can you guys help me with a Minitor I, It's a VHF Hi pager I believe, and on the crystal it has a frequency of 17.25278.

Anyone got a operating frequency?

k2hz · Post by **k2hz** » Thu Aug 25, 2005 4:33 am

VE9MP wrote:Can you guys help me with a Minitor I, It's a VHF Hi pager I believe, and on the crystal it has a frequency of 17.25278.

Anyone got a operating frequency?

The Minitor I high band xtal formula is (f-10.7)/8.

17.25278 x 8 = 138.02224 + 10.7 = 148.72224

That is an odd frequency, are you sure of the xtal frequency or that it is VHF HI?

Post by **VE9MP** » Thu Aug 25, 2005 6:10 am

k2hz wrote:
VE9MP wrote:Can you guys help me with a Minitor I, It's a VHF Hi pager I believe, and on the crystal it has a frequency of 17.25278.

Anyone got a operating frequency?
The Minitor I high band xtal formula is (f-10.7)/8.

17.25278 x 8 = 138.02224 + 10.7 = 148.72224

That is an odd frequency, are you sure of the xtal frequency or that it is VHF HI?

I thaught it was.....but maybe its not? Lowband perhaps? UHF? I was told it was high band when I got it, but I haven't really messed around with it...

MOTO_LR · Post by **MOTO_LR** » Thu Aug 25, 2005 8:24 am

Nick,

Minitor I VHF High Band...

17.25278 = 155.730 MHz.

The crystal formula is:

Crystal freq = (Channel freq - 0.455) / 9

Bob

k2hz · Post by **k2hz** » Thu Aug 25, 2005 9:37 am

Bob is correct, The VHF Minitor I uses the same xtal for both mixers with a
variable high IF. I was thinking of the Low Band that is a fixed 10.7 IF.
It does use xtal freq X 8 for the first injection but then uses the xtal freq again for the conversion to 455. This results in the correct formula that Bob used.

Sorry about the confusion. I am glad Bob corrected it.

Post by **VE9MP** » Thu Aug 25, 2005 10:05 am

Thanks guys!