This probably will not work on the Mitrek since it may not use slugs to tune
the coil, but I had a problem with a crystal on a Delta radio that would not go
low enough in frequency. I removed the slug from the F2 coil and ran the slug
for the F1 coil through max inductance and then added the second slug on top of
the first. The combined slugs allowed me to net the crystal.
73 - Jim W5ZIT
--- On Sat, 12/20/08, Eric Lemmon <wb6...@verizon.net> wrote:
From: Eric Lemmon <wb6...@verizon.net>
Subject: [Repeater-Builder] Converting a Range 2 VHF Mitrek to Range 1 (WAS:
Holiday Special...)
To: Repeater-Builder@yahoogroups.com
Date: Saturday, December 20, 2008, 9:27 AM
Only one of the five front-end coils for a Range 1 VHF Mitrek
(HLD4081,
136-146 MHz) is still available from Motorola Parts. That one is part
2480032A07, the violet coil in L1, for $ 4.15.
The only option may be to tack on some extra wire to the existing coils.
Although modifying the tuning screws may work, I suspect the Q will suffer.
73, Eric Lemmon WB6FLY
-----Original Message-----
From: Repeater-Builder@ yahoogroups. com
[mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of Kevin Custer
Sent: Friday, December 19, 2008 9:30 PM
To: Repeater-Builder@ yahoogroups. com
Subject: Re: [Repeater-Builder] Holiday Special - MICOR 2 meter receiver
conversion from W3KKC
Tom,
Okay.... I guess I should ask if replacement coils for the Mitrek are
still available from Motorola, and if so, at what cost? If they are no
longer available, or are cost prohibitive, send me one of your Mitrek
receivers and I'll see if I can come up with a new set of coils that
properly tune the whole 2M band.
I guess at this point we should go to private email.
Kevin
Hello Kevin
Thanks for your reply. Your statement is correct in that all of
the receiver coils begin to tune at the bottom of their travel. I have even
tuned two or three too far and they dropped out with the resulting work to
retrieve the screws. When tuned as best I can for sens the s/n ratio is
1+uv at 12db sinad. The original frequency sens was less than 1uv-usually
about .3uv for 12db sinad. Replacing the coils are about the only solution
I know of for these high split VHF units. I have in the past replaced two
sets of receiver coils with Motorola coils and found I have good sensitivity
as before modification. The transmitters all tuned well on this split and
gave rated or more power output.
The Mitrek coils looked very much like the Micor coils. I have
replaced probably a half dozen Micor receiver coils proscured from Motorola
in the past 20 or so years. Thanks. 73 de Tom Manning, AF4UG
----- Original Message -----
From: Kevin Custer <mailto:kug...@kuggie. com>
To: Repeater-Builder@ yahoogroups. com
<mailto:Repeater-Builder@ yahoogroups. com>
Sent: Thursday, December 18, 2008 10:02 PM
Subject: Re: [Repeater-Builder] Holiday Special - MICOR 2
meter receiver conversion from W3KKC
Tom,
You say you find similar operation on 4 or 5 units. By that
do you mean they won't make book specification on any frequency below 146
MHz? If that is the case, I would believe something is wrong. I have seen
many Mitrek high-band receivers that were tuned for 144 something and had
very good sensitivity.
Let me ask you this.... When tuned at 144.89, is the
front-end tuning all "one ended", or is there adjustment to spare? In other
words, can you tune the front-end without the fear of the tuning screws
falling into the casting? If you have room left to go lower in frequency,
then the front-end is not the problem, and you'll need to look elsewhere for
the lack of sensitivity. Another question - do these 4 or 5 units tune
and make book spec sensitivity on their original high-band channel?
I guess what I'm saying is I doubt the problem is the
front-end helical resonators, but if there is a need for a conversion I'm
not opposed to looking into making a modification available, if it is
needed. If there are others on the list that have had good luck with the
Mitrek on frequencies below 146 MHz, please chime in and let us know what
you have and how well it works.
Kevin
Hello Kevin
You are correct on your freqs for xmit and rcv.
The Mitrek units I have will only tune receive to 146.00Mhz. This leaves
more than one meg to go to meet tolerance on 144.890. I have tried 4 or 5
units and find similar operation of all. This is the reason for my question
about the Micor coils working for Mitrek. Thanks. 73 de Tom Manning, AF4UG
----- Original Message -----
From: Kevin Custer
<mailto:kug...@kuggie. com>
To: Repeater-Builder@ yahoogroups. com
<mailto:Repeater-Builder@ yahoogroups. com>
Sent: Tuesday, December 16, 2008 8:44 PM
Subject: Re: [Repeater-Builder] Holiday
Special - MICOR 2 meter receiver conversion from W3KKC
Tom,
Do you mean 144.89 MHz? I would think your
repeater would *transmit* on 145.490 MHz.... At any rate, no conversion is
necessary for the Mitrek to make book specification sensitivity on 144.890
MHz.
Kevin
Good afternoon Kevin
My need is to convert two or
more Mitrek receivers to cover 145.49Mhzz, which is our receive freq for our
repeater. Thanks. 73 de Tom Manning, AF4UG
----- Original Message -----
From: Kevin Custer
<mailto:kug...@kuggie. com>
To:
Repeater-Builder@ yahoogroups. com <mailto:Repeater-Builder@ yahoogroups. com>
Sent: Tuesday, December 16,
2008 12:19 PM
Subject: Re:
[Repeater-Builder] Holiday Special - MICOR 2 meter receiver conversion from
W3KKC
Tom Manning wrote:
Good morning Kevin
I have a
question. Will these coils also work in a Mitrek? Thanks. 73 de Tom
Manning, AF4UG
Hi Tom,
To answer your question, the
conversion will not work in the Mitrek.
Unlike the MICOR, the Mitrek
high-band unit that is most common has a lower tuning limit of 146.00 MHz as
specified from the factory. This means that the units normally tune
anywhere in the 2M ham band without modification. What frequency do you
need to listen on?
Kevin
