[MAMS] PLL

[mary boller]

Many thanks for the info. I have a pretty good rig on 5760 right now,but it 
still has the DEMI microloc and the only problem with that is finding me on the 
dial while the thing settles down. YOu are right about the minus twenty I got a 
1.5 watt Harris amp from the same guy to better drive my Spectrian strip. The 
minus sign was now clearly printed and I learned very quickly. Didn't do any 
damage and with minus 20 it works great. Wouldn't happen to know where a guy 
could latch on to a print of the pll???  




________________________________
From: Dr. Gerald N. Johnson <geraldj at weather.net>
To: mams at mailman.qth.net
Sent: Thu, January 6, 2011 10:25:59 AM
Subject: Re: [MAMS] PLL

The output frequency is 60 times the crystal frequency as marked. My 
first guess is that its a knock off of the common Frequencies West PLL. 
Which would be locking a power voltage controlled oscillator in the 1.5 
to 2 GHz region to to a crystal harmonic, then picking off the 3rd or 
4th harmonic of that oscillator with a step recovery diode and filter. 
15th harmonic of the crystal is 1.581.6 MHz and the 20th is 21080.8 GHz. 
FW blocks tend to drive the phase detector with the second harmonic of 
the crystal (e.g. 2x) so the second scheme is more likely. As it sits 
the output is 566.54 MHz above 5760, an inconvenient IF frequency. 4 
times the output is 25306.16, 1114.160 above 24192, not a great IF 
frequency.

It might be possible to tune the VCO to pick off different harmonics of 
the existing crystal, but changing the crystal is probably practical, if 
one can work out the crystal parameters to get one with adequate 
frequency stability. And it may be possible to tune the output filter to 
a different frequency or maybe even harmonic if the presumed VCO range.

With the range rated as 5.8 to 7.2 I presume the output filter and the 
VCO will tune at least that far, so its probable that without changing 
the crystal to tune to all even (based on FW details) harmonics of the 
crystal in the VCO range and multiply the VCO by factors of 3, 4, or 
maybe 5 by retuning the VCO and the output filter.

In that collection of units, its probably that not all have the same 
frequency crystal. Its very likely possible to change the crystal for 
$30 or 40 buck a crystal to get a handier frequency though the handiest 
application for a 6 GHz range unit has been either a 5760 beacon or 
using the second harmonic for 24 GHz LO with half frequency injection.

The other unhandy thing about FW blocks is that they mostly run on -20 
volts.

73, Jerry, K0CQ

On 1/6/2011 9:33 AM, mary boller wrote:
> I have a Harris microwave pll for 5.8 to7.2 GHz, and I know where there are
> several more like it at reasonable prices. I have absolutely no information
> whatsoever on how to hook it up or power it. There are five wires going in.
>
> The model number is SD110009-106 S/n is 14 and the date code is 1196. There is 
>a
> website called Star Microwave that lists it. but I have not been able to bring
> up any info. I am also pretty sure that the contacts I had at Harris 20 years
> ago are long gone. So, the questions are: Is it usable for ham frequencies. I
> sent it to Randy, WB0JQQ and he is not sure if it can be retuned without a new
> crystal. The frequencies listed on the outside that are adjustable are
> 6326.540mhz and 105.44233 mhz. I also aquired an lna from the same equipment 
>and
> it really works good. It is so well built you could drive over it with a car 
>and
> not damage it at all.
> Anybody : Recognize the PLL: have any  printed info on it: know where info can
> be obtained:. I will ship it to anyone who might be interested in reverse
> engineering it
> Wally Boller, W9OBG
>
>
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