[Collins] Questions about the Collins 18S and 618* equipment

Tue Apr 21 20:33:12 EDT 2009

Hi All,

I have scanned manuals of the 618S1 and 618S4 service manual,  618S-1 and 
618S-1A parts manual, and 618S-1 parts group which is the 11 x 17 pages. 
These are not currently on the CCA website but I will see if we can  get 
them posted soon. I also have some ART-13 manuals that could also be added. 
However these are not the quality of the Amateur Equipment that we have 
provided in the past. They are however better than nothing. They are very 
large files and will take sometime to download. Currently our webmaster is 
up to his ears in work and duties at home.

If you have any other manuals from this time frame and are willing to loan 
me please let me know. Spring is upon us now which means I will be out doing 
yard work like next week so it may take awhile to get something scanned and 
returned.  Please keep this in mind and for now let me know what you may 
have available.  I am also still looking for Collins Broadcast equipment and 
audio consoles that we do not currently have.

Thanks for the read!

73 Larry WA9VRH
Collins Collectors Association Archive Manager

----- Original Message ----- 
From: "Dr. Gerald N. Johnson" <geraldj at storm.weather.net>
To: <collins at mailman.qth.net>
Sent: Tuesday, April 21, 2009 10:43 AM
Subject: Re: [Collins] Questions about the Collins 18S and 618* equipment

> On Mon, 2009-04-20 at 11:10 -1000, Michael Tauson wrote:
>> The 18S-* and 618* equipment has been on my mind a lot of late.  This
>> isn’t the first time they have fallen under my curious eye but it has
>> lead to some questions about them.
>>
>> I have an 18S-4 but lack a schematic and information on the coils &
>> output network to move it into the ham bands.  (None of the crystals
>> that came with it were even close.)  If anyone has this information
>> and would be willing to share (plus any tune up hints), I would be
>> grateful.
>
> I don't have those details either. Perhaps CCA has some of them.
>
> With plug in crystals and coils, one way to get LSB is to select a
> crystal on the opposite side of the injection as used to get USB.
>
> In some of the rigs, a USB filter is used, and it at least conceptually
> its possible to add filter switching to allow using both a USB and a LSB
> filter for the same carrier frequency while preserving the frequency
> calibration. Otherwise, at a loss of frequency calibration, its
> practical to shift the BFO to the other side of the filter passband. In
> S-line that's how its done, with the addition of a frequency shifter in
> the PTO to shift it in the opposite direction so the dial stays the same
> for the same carrier frequency.
>>
>> Next, is the 618M-1 the same as a 618S-1/MC?  If not, what is it?
>>
>> What (if any) modules are interchangeable between the 618S-1 &
>> RT-311/ARC-38, the 618S-1/MC & RT-594/ARC-38S and between the two
>> groups?  Also, does anyone know of a way to make the SSB versions
>> operate on LSB?
>>
>> The same question exists between the various versions of the 618T and
>> the military versions thereof.  Also, was there any restrictions on
>> the sets that wouldn’t allow them to operate in CW or data mode or was
>> that simply a function of the control head?
>>
>> And finally, is there any way to make the 618S and 618T series
>> equipment able to tune between the 1 KCs divisions (like the
>> RT-662/GRC-106) or is that a near impossible can of worms?
>
> When the rig is based on a digital synthesizer, its hard with the
> existing logic to split the 1 KHz reference. But if there is an offset
> oscillator because of slow logic, its possible to do fine tuning by
> warping that offset oscillator, or to warp the synthesizer reference to
> get fine tuning. Today, one can get a single chip synthesizer that will
> do fractional N ratios to get arbitrarily fine steps while keeping a
> coarser reference frequency.
>
> And then there's direct digital synthesis techniques that create signals
> at an arbitrary frequency with a couple chips in a package. There's some
> discussion at: http://softrocksdr.wikispaces.com/
>
> Possibly a ham vendor like AADE has a general purpose DDS or synthesizer
> that could replace the limited capability of the original synthesizer.
> At the cost of an external dial or control, unhooking a cable or two
> inside the radio, and possibly having to compute frequency different
> than the synthesizer display.
>>
>> Thank you.
>>
>> Best regards,
>>
>> Michael, WH7HG
>
> -- 
> 73, Jerry, K0CQ, Technical Advisor to the CRA
> All content copyright Dr. Gerald N. Johnson, electrical engineer
>
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