At this time on eBay there's an auction for MX340s which
are VHF SP units with a feature I've not seen before. It looks
as if Motorola put an offset crystal or crystals in a four-channel
VHF radio. I've only seen offset rocks in UHF units until now, those
being 5 mHz or 3 mHz, and I think there was another odd offset
offered. The label on the VHF units says all four channels are
simplex, but the switch on the top tells me that there are offsets
built in. I'm wondering if anyone has encountered these units
before and how common they were, which I'd bet is "not very."
MX340 with talkaround/offset switch
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Tom in D.C.
- Posts: 3859
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- What radios do you own?: Progreso soup can with CRT
MX340 with talkaround/offset switch
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
Re: MX340 with talkaround/offset switch
My two bits worth:
As I recall the VHF MX 300 used separate channel elements for receive and transmit.
Since the VHF band in the US generally has no standard for TX-RX separation an offset crystal would only be useful if all channels had a common separation, such as mobile telephones, or ham repeaters.
Being the -S model, I would GUESS that the "repeat" switch is in fact a ZONE switch.
That is Zone A F1 might be the repeater pair, Zone B F1 is talk around.
As I recall the VHF MX 300 used separate channel elements for receive and transmit.
Since the VHF band in the US generally has no standard for TX-RX separation an offset crystal would only be useful if all channels had a common separation, such as mobile telephones, or ham repeaters.
Being the -S model, I would GUESS that the "repeat" switch is in fact a ZONE switch.
That is Zone A F1 might be the repeater pair, Zone B F1 is talk around.
Aloha, Bernie
Re: MX340 with talkaround/offset switch
A MX340S would have the PROM and can be programed any old way, no channel elements.
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Tom in D.C.
- Posts: 3859
- Joined: Tue Sep 04, 2001 4:00 pm
- What radios do you own?: Progreso soup can with CRT
Re: MX340 with talkaround/offset switch
These do NOT appear to be S models; they look to me like they're
crystal element radios like i used to work on, and the top
toggle switch says "OFF-RPT" which I've never seen before. The
back tag lists four channels, all simplex, with CH1 being different
from 2, 3, and 4, while 2, 3, and 4 are listed as the same frequency.
The first question is whether Motorola made an SP MX for VHF with an
offset element, and the second one is if anyone has come across this
kind of setup before. Apparently these radios were used by Indiana
State Police.
crystal element radios like i used to work on, and the top
toggle switch says "OFF-RPT" which I've never seen before. The
back tag lists four channels, all simplex, with CH1 being different
from 2, 3, and 4, while 2, 3, and 4 are listed as the same frequency.
The first question is whether Motorola made an SP MX for VHF with an
offset element, and the second one is if anyone has come across this
kind of setup before. Apparently these radios were used by Indiana
State Police.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
Re: MX340 with talkaround/offset switch
The state police cars had mobile "extenders" in them which are simplex "repeaters" which talk to the HT on VHF. As CHP uses in California, on 154.905 (but soon going to 700 MHz.) The RPT-OFF switch should turn the PL encode off on the MX so that the portables can talk to each other without tripping the mobile extender unit in the car. No PL no repeat. But the portables will still hear dispatch and other cars being repeated through the car system, so they won't miss anything while they are talking to each other.