[NLRS] Parts is parts

[Dan Larson]

On Thu, 5 Feb 2004 10:59:19 -0600, Ross Vaagen wrote:

>The 8615 is a 800 mhz trunking radio that worked in the 806-870 (approx)
>area. The trunking format had a 45 mhz split. I don't believe they are
>capable of conventional FM (Simplex). I can check on that if you need me
>too.

Well, at least I know a little more about those radios, then!

Let me guess then, that part of the cellular band hides in between
the tx & rx channels. 

There is a nice ceramic block "resonator" in there which is probably 
the one component other than the PA driver module that wouldn't take
too kindly to 902-928 out of band MHz signals in receive.

>
>The company I work for has programming capabilities.
>
>Microphones, brackets, and powercords are available from EFJ or used market.
>

I don't think I want to cause trouble with local licensed users of the band (HI HI),
so microphones, brackets, and programming won't do me any good since they probably
won't ever be modifiable for 33cm.

It doesn't sound like they will do me much good either, with the original 
CPU in the radio if it wants to live life as a trunking radio.

So, am I safe to assume that these radios are only useful for parts then?
( to a HAM anyway,......)

I can't read the frequency on the TCXO contained within. The part number doesn't
make much sense to me. Do you happen to know what the output frequency of the
TCXO is? Those TCXO's look like they would be mighty nice for my own PLL / DDS 
projects.

>It would be interesting to see a 900 mhz rptr. Not enough hams in my area to
>justify. :-(

Well, I don't even think we have any 900MHz repeaters in the twin cities other than
the one ATV repeater I know of. Its too bad no body wants to make radios for 33cm.
I'd love to get on the band, but it looks like the only action is SSB with the NLRS
guys., so I will have to plan on building a transverter some day.

Ross
Thanks Ross!

de Dan KC0LUY

>
>----- Original Message ----- 
>From: "Dan Larson" <kc0luy@arrl.net>
>To: "nlrs" <nlrs@mailman.qth.net>
>Sent: Thursday, February 05, 2004 10:16 AM
>Subject: [NLRS] Parts is parts
>
>
>> Hello everyone.
>>
>>
>> I have recently come into possession of some cast away 2-way radio
>> gear with some interesting parts, and I would like to ask the group
>> what I might be able to do with them.
>>
>> The radios are E.F. Johnson Model #242-8615 800Mhz 2-way FM rigs. They
>were
>> apparently used with radio modems for digital purposes, since no
>microphones
>> came with them. They did have serial cables hanging out and were attached
>> to DataRadio modems. The speaker in the unit tells me it was capable of
>> 2-way audio.
>>
>> Inside the final PA transistor is an MRF847 45W out with 16W in. The
>> PA transistor is driven by a MHW820-1 802-870MHz module spec'd at
>> 250mW in with 20W out.
>>
>> I doubt that the module would be useful since 902-928 is way outside
>> of its spec'd frequency range. But, perhaps at lower power might I get
>> anything at all out of them?.......
>>
>> The MRF847 sounds like it could be put to good use in a 12V 900MHz amp.
>>
>> Does anyone know if the radio itself could be modified for 900MHz by
>> replacing the driver module with one capable of 900-928 MHz? Of course,
>> that requires that the CPU / PLL and receive front ends could also be
>> made to operate at the higher frequencies. I *am* capable of building
>> my own CPU to drive the MC145159 PLL IC. I have experience with AVR
>> and PIC microcontrollers.
>>
>> Just wanted to know what anyone might be able to tell me about this
>> radio and / or its parts. Even if I can't make anything for 900MHz
>> out of it, those PA transistors might still make good final amps
>> for 432MHz or 222MHz. I've got a stash of MRF517's I could use to
>> drive them with. But what good is an amp with no radio to amplify?
>> I have not built a 900MHz transverter yet.
>>
>> Dan KC0LUY
>>
>>
>>
>>
>>
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>
>