[Milsurplus] looking for R-390 and -A meters

[Jim Whartenby]

BrianA VU meter is a VU meter so if it fits, it is good to go.
The Carrier Level meter is a different story.  I have used meters from other military radios as replacements.  The meters used are the same physical size and appearance of the original Collins meters so if you didn't know beforehand, I doubt that you would notice any difference.  
Here is a note from 2006 by Pete Williams from "the land down under" on the procedure to go from the original 10 ohm meter movement to one that uses a 100 ohm / 1 mA meter movement.
"Hi...While some of you guys have been getting legless from taking theplate caps off 807's, some of us at the other end of the day havebeen active in being practical in adapting surplus meters for thecarrier level function in R-390A.

Theoriginal meter has an internal R of around 10 Ohms and thereplacement meter I have (ex W5cab) has an Internal R of around 103ohms. It has a FSD of 1 mA. The scale plate changed per fotodetails available on the net.


Altho'it deflects, the reading is a fraction of the original. Followingsuggestions made by David Wise and Gary Gitzen, modifications made tothe meter bridge circuit gave identical results to that generatedwith original meters.


Notonly was meter deflection approximately the same (Even readings fromoriginal meters varied under the same test conditions) but theparameters of linearity and AGC also remained identical to readingsobtained with the original meters during the tests . Time constantvalues also appeared to be the same as original.


MODIFICATION: Refer to Fig 22 on page 36 of manual TM 11-5820-358-35.


ReplaceR524 with a 600 ohm resistor. Replace R548 with a 160 ohm resistor .Both are easy to get at.

RemoveR537 a 22 ohm resistor from the carrier meter adjust pot ..


Removethe shorting link from the center wiper terminal of this pot andconnect the white-blue-orange wire to the "hot end" of thepot. The white-blue-green stays on the center wiper and it isalready connected to the + side of meter, M102. The white wire staysgoing to chassis. Zero the meter as per the manual and that's it .


NOTE....other meters of greatly differing IR's may require modification ofthe resistor values... none were available for test.

Thanksto Dave and Gary for interest and assistance with thesemodifications.
Puristscan get on with evacuating 807's!
CheersPeteD . WilliamsMETUNG3904 Australiajupete at bigpond.net.au"
I have used the above procedure with great success on several R-390As.  The meters I used were from several SRR-13 receivers that had I scrapped due to physical, smoke and fire damage.  Most of these receivers were missing modules and would have required much more effort to bring back to life then I was willing to expend.  The more complete receivers I have repaired or have saved for a rainy day.  The SRR/FRR series of receivers are good performers and don't deserve the reputation they seem to have, IMHO.  Plus the fact that they used mechanical filters, long before the non-A R-390 receiver entered inventory.

If you cannot find appropriate meters, let me know and I'll check my box of SRR/FRR spare parts for meter sets.Regards,Jim
I wonder why people argue over the 10% of their differences and ignore the 90% they agree on? 

    On Friday, February 15, 2019, 8:35:45 AM CST, Brian Harrison <briankn4r at gmail.com> wrote:  
 
 Hi all,
I’ve come into a few R-390s and -As with no meters
Would anyone on the list have any for sale?  Or know of a quantity source?
Tnx and please email me off list
briankn4r at gmail.com
(also I’m good on QRZ)
Tnx and all the best,
briankn4r______________________________________________________________
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