I have a TRC-458 (Has the 858 PLL). I need to replace the switches for
the extra channels. The mod that I found says to use two switches -
one SPST and one SPDT center off. The switches that are currently in
the radio (and are broken) are DPDT switches. The one in the S1
position only has two wires hooked up to it. The S2 has three wires.
The wires are soldered across both rows on each switch.

My question is this - should I replace the switches with what the mod
says or use the same switches as what's in there? I'm assuming that
the person that did the mod may not have had the right switches, so he
just used DPDT switches instead. The previous owner of the radio said
that the buttons on front, for the NB, etc... are also used with the
extra channels, but the mod I found makes no mention of extra channels
with these buttons.

Any ideas?

(2LD751) wrote in message . com...
I have a TRC-458 (Has the 858 PLL). I need to replace the switches for
the extra channels. The mod that I found says to use two switches -
one SPST and one SPDT center off. The switches that are currently in
the radio (and are broken) are DPDT switches. The one in the S1
position only has two wires hooked up to it. The S2 has three wires.
The wires are soldered across both rows on each switch.

My question is this - should I replace the switches with what the mod
says or use the same switches as what's in there? I'm assuming that
the person that did the mod may not have had the right switches, so he
just used DPDT switches instead. The previous owner of the radio said
that the buttons on front, for the NB, etc... are also used with the
extra channels, but the mod I found makes no mention of extra channels
with these buttons.

Any ideas?

dont worry about the extra channels....you are not a ham and you are
not authorized to go into the radio chassis and mess around........my
advice forget it.........your post has been logged by your lords and
masters..........AKC4L...........

On 10 Mar 2004 09:40:20 -0800, (2LD751) wrote:

I have a TRC-458 (Has the 858 PLL). I need to replace the switches for
the extra channels. The mod that I found says to use two switches -
one SPST and one SPDT center off. The switches that are currently in
the radio (and are broken) are DPDT switches. The one in the S1
position only has two wires hooked up to it. The S2 has three wires.
The wires are soldered across both rows on each switch.

My question is this - should I replace the switches with what the mod
says or use the same switches as what's in there? I'm assuming that
the person that did the mod may not have had the right switches, so he
just used DPDT switches instead. The previous owner of the radio said
that the buttons on front, for the NB, etc... are also used with the
extra channels, but the mod I found makes no mention of extra channels
with these buttons.

Any ideas?


The thing with extra channel modifications are that each "tech" has
their own "style" WRT how the mod is implemented. I could not even
begin to fathom what the thought process was when the original mod was
made.

The only thing I can tell you is that the upd-858 PLL uses a BCD
(Binary coded decimal) encoder for the /N counter. The pins that are
of the most interest to channel expanders is 22, 21, 20, 19 and 13
(for the gap channels). In order to understand the relationship of how
each pin relates to frequency selection, it becomes helpful to create
a truth chart for the known frequencies. From there it become easy to
extrapolate additional frequencies.

This PLL is capable of synthesizing 399 individual "channels".
However, the radios bandwidth limits practical range to around 200
channels. A stock radio, with the factory crystals will start at
26.065, and end at 30.055 Mhz. The VCO can be tuned to any 2 Mhz
segment within that range.

IMHO, this Uniden 858 chassis has been my all time favorite CB
chassis. There were a lot of interesting modifications that could be
done, and it performed well too.

Dave
"Sandbagger"
http://home.ptd.net/~n3cvj

"2LD751" wrote in message
om...
I have a TRC-458 (Has the 858 PLL). I need to replace the switches for
the extra channels. The mod that I found says to use two switches -
one SPST and one SPDT center off. The switches that are currently in
the radio (and are broken) are DPDT switches. The one in the S1
position only has two wires hooked up to it. The S2 has three wires.
The wires are soldered across both rows on each switch.

My question is this - should I replace the switches with what the mod
says or use the same switches as what's in there? I'm assuming that
the person that did the mod may not have had the right switches, so he
just used DPDT switches instead. The previous owner of the radio said
that the buttons on front, for the NB, etc... are also used with the
extra channels, but the mod I found makes no mention of extra channels
with these buttons.

Any ideas?

I replaced the broken switches with the SPST and SPDT switches as the mod
says, and I only get the standard 40 channels. With the switches in the
other positions, I don't get the standard channels according to the mod
commonly found on the net. I'll replace them with the same switches that
were in there (apparently two DPDT switches) and see what happens. Once
that's done, I'll have to tackle the problem of why there's no audio with
two different mic's. I'd still like to know what mod the tech went by, as is
appears pushing some of the front buttons affect the frequency, but I
suppose that might be an after effect of not having the right switches.

Once the switches are replaced and I have the results, I'll post it here for
information.

On Thu, 11 Mar 2004 23:20:54 -0500, "Andy in NJ" SHORECOGS at COMCAST
DOT NET wrote:

"2LD751" wrote in message
. com...
I have a TRC-458 (Has the 858 PLL). I need to replace the switches for
the extra channels. The mod that I found says to use two switches -
one SPST and one SPDT center off. The switches that are currently in
the radio (and are broken) are DPDT switches. The one in the S1
position only has two wires hooked up to it. The S2 has three wires.
The wires are soldered across both rows on each switch.

My question is this - should I replace the switches with what the mod
says or use the same switches as what's in there? I'm assuming that
the person that did the mod may not have had the right switches, so he
just used DPDT switches instead. The previous owner of the radio said
that the buttons on front, for the NB, etc... are also used with the
extra channels, but the mod I found makes no mention of extra channels
with these buttons.

Any ideas?

I replaced the broken switches with the SPST and SPDT switches as the mod
says, and I only get the standard 40 channels. With the switches in the
other positions, I don't get the standard channels according to the mod
commonly found on the net.

That's what I was referring to when I said that everybody had their
own "style". You may have to use a different method to access the
channels, according to the style that your particular mod was made.



I'll replace them with the same switches that
were in there (apparently two DPDT switches) and see what happens. Once
that's done, I'll have to tackle the problem of why there's no audio with
two different mic's.

Now that could be a problem. What are the particulars? Does the radio
have receive audio? Does it have modulation on SSB? The chances are
that two different mikes are not both bad. But it does help to check
them on a known good radio.


I'd still like to know what mod the tech went by, as is
appears pushing some of the front buttons affect the frequency, but I
suppose that might be an after effect of not having the right switches.

The original tech may have utilized the PA and ANL -NB switches for
some of the frequency mods. I never liked doing that unless you could
get by with a single switch (which was rare). As long as you are
required to use more switches than what's available on the radio, you
might as well use all external switches, and leave the factory
functionality intact.



Once the switches are replaced and I have the results, I'll post it here for
information.


I'd like to hear how you made out.

Dave
"Sandbagger"
http://home.ptd.net/~n3cvj

how come none of this was mentioned while this radio was at auction on ebay?

I replaced the broken switches with the SPST and SPDT switches as the mod
says, and I only get the standard 40 channels. With the switches in the
other positions, I don't get the standard channels according to the mod
commonly found on the net. I'll replace them with the same switches that
were in there (apparently two DPDT switches) and see what happens. Once
that's done, I'll have to tackle the problem of why there's no audio with
two different mic's. I'd still like to know what mod the tech went by, as is
appears pushing some of the front buttons affect the frequency, but I
suppose that might be an after effect of not having the right switches.

Once the switches are replaced and I have the results, I'll post it here for
information.

"Dave Hall" wrote in message
news
On Thu, 11 Mar 2004 23:20:54 -0500, "Andy in NJ" SHORECOGS at COMCAST
DOT NET wrote:
Now that could be a problem. What are the particulars? Does the radio
have receive audio? Does it have modulation on SSB? The chances are
that two different mikes are not both bad. But it does help to check
them on a known good radio.

There is receive audio, no modulation on AM or SSB.

"MrTimNebo" wrote in message
...
how come none of this was mentioned while this radio was at auction on
ebay?

The broken switches were mentioned on Ebay. The audio was untested as of
when it was put on Ebay. Since I decided to keep it and try to get it
working, I've found there might be a problem with the audio.

Why do you ask, you wanna buy it from me?

On Fri, 12 Mar 2004 16:51:08 -0500, "Andy in NJ" SHORECOGS at COMCAST
DOT NET wrote:

"Dave Hall" wrote in message
news
On Thu, 11 Mar 2004 23:20:54 -0500, "Andy in NJ" SHORECOGS at COMCAST
DOT NET wrote:
Now that could be a problem. What are the particulars? Does the radio
have receive audio? Does it have modulation on SSB? The chances are
that two different mikes are not both bad. But it does help to check
them on a known good radio.

There is receive audio, no modulation on AM or SSB.



That's good news as it eliminates the audio amp/modulator I.C., which
has been discontinued and is generally not available, except from
someone who might have some old stock.

Assuming that the mikes are good (and wired correctly!), your best bet
would be checking the mike preamp I.C., and the related circuitry.
This is something that might be best accomplished with an
oscilloscope, (working forward) or a signal injector (working
backward).

Dave
"Sandbagger"
http://home.ptd.net/~n3cvj