1). James Garland reminded me that the S-meter pegging when the VFO is turned CCW is normal behavior. Decreasing the RF gain increases the AGC voltage (to cut off the RF and IF stages), and the S-meter basically measures the AGC voltage. Turning down the RF gain control should cause the S-meter to continuously increase, even with no signal present.
2). Component values shift with age. Changes in these values (in particular, R158, R147 and V1B) will cause the S-meter to read "hot".
3). John, K0LFA informed me that Collins had a mod to the S-meter circuit. It is from "Amateur service Agency Bulletin No. 1009 ? Item 3"
KWM-2,-2A; Increase Accuracy Of “S” Meter and Extend Range Of Zeroing Potentiometer
On parts mounting turret E40, between terminals C and D, remove resistor R147, 82K 1/2 watt and replace with R147, 68K ohm +-10% 1/2 watt (CPN 745-1429-00). Also on turret E40, between terminals C and E, remove resistor 158, 270 ohm 1/2 watt and replace with R158, 220 ohm +-10% 1/2 watt (CPN 745-1324-00).
This mod should be in place.
4). Gayle Lawson and Firn Rivard pointed out that there is an adjustment
procedure for R158. It is described in section 4.7.4 of the KWM-2
manual (I overlooked this). Richard Webster (a retired Collins
Engineer) told me the factor test procedure (which seems better than the
manual). It is:
6.9 Receiver Alignment
1. Set the signal generator for a 1.8 uv unmodulated 14.3 mhz,
LSB output and tune the KWM-2/2A to this frequency (maximum S-meter
indication).
2. Set R132 (RCVR Gain Adj) full CW and peak the EXCITER
TUNING.
3. Peak L9 and T5 for a maximum S-meter reading, then set the
RCVR GAIN ADJ pot for AGC threshold as read on the S-meter (S-1 indication).
4. Set the signal level to 100 uv and note the S-meter
indication S8 to S9+10db. Switch to USB and measure signal generator input
required for the same S-meter reading (Should be +/- 3 db of input required for
LSB).
5. If not, connect a decade resistor across R158 and select a
resistance that produces a reading of S-9.
The signal generator should be connected to the receiver's input via the circuit shown in Figure 4-3 of the KWM-2 manual. This circuit is a 50 ohm, 6db attenuator pad.
Kurt Keller brought to my attention that Collins intended to have the value of R158 adjusted by placing another resistor in parallel (R158A).
In summary, I plan to:
Check for (and make if not present) the 1009 modification.
Check V1 on my mutual conductance tube tester.
Perform Richard Webster's procedure.
Go back and reread my circuits books on AGC, RF and IF circuits. I
should have remembered what the RF gain pot is actually doing!
I usually disassemble completely Collins meters, mostly S-Line meters, and removed the glass completely. Most of the glass I've encountered was held in with a (brass?) "ring" pressed against the glass and over the years it has become too weak to hold.
I've had good luck using various hardware store cements (like the old model airplane cement or Duco or the like) to hold both the meter glass and the ring in place where it belongs. Of course, clean the glass very well first and the same for the meter shell. If you choose to put glue/cement on the meter shell front where the glass mates, make sure you don't leave a trace of it visible from the front to harden.
If the original meter was panted white inside, this is also a good time to repaint but protect the inside of the glass very well as it's hard for me anyway to clean it well once it's in place again.
Of course, you also give the meter face a good cleaning after carefully removing it from the movement. Before you fasten the screws around the periphery of the meter after assembly make sure you have no flecks of dirt or lint or streaks on the face. Though I find it difficult to clean the glass really well with it in the meter shell, I will do all I can to avoid having those annoying streaks or pieces of dirt forever in front of me in a lighted meter.
Ian, K6SDE
Remove the meter from the case.
Most meters (and I've done this to many) have 3 small brass screws that are spaced around the cylindrical barrel of the meter case. Remove the three screws.
CAREFULLY remove the meter front, being cautious not to rotate the parts being separated, particularly until you have separated the two pieces by half an inch or so.
(If you do rotate it very much you may leave some bits of paint/plastic shavings that are created in the meter and you don't want to hang up on the zero adjust screw that projects from the front into the meter.)
Clean/refurbish, polish and make like new as you wish.
Reverse the process to reassemble, being careful that the zero adjust is lined up so it doesn't press on one of the prongs of the "fork" of the zero adjust mechanism as the pieces slide together.
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I ALWAYS remove the meters and thoroughly clean them when I work on Collins gear. Often the meter glass is loose as well. When reassembling, you may have to use a bit of duco cement or similar to make sure the glass stays in position as the brass "keeper" that pushes against the glass sometimes no longer fits tightly.
I often remove the meter glass from the front of the meter case, clean it thoroughly, including the areas that are hidden behind the front of the plastic bezel. I have also repainted the white inside the case of some of the meters after I lightly sand off the remnants of the old dried out chipping original paint. I put the meter glass back and fix it firmly before doing any painting and of course mask and protect the glass from the paint. Otherwise pushing in the brass piece that keeps the glass in scrapes off the new paint. This returns the illumination to the level that it was when the gear was new. Some people like to apply an anti-static cleaner as the last step though you can accomplish much the same with some dishwashing liquid.
You may wish to CAREFULLY remove the meter scale at the same time and clean it. It may be heresy but I've always used some liquid hand soap on my finger tips and "washed" the scales carefully with finger tip pressure then rinsed well with tepid water and patted dry followed by a bit of time in the warm sun. So far I've never had to do anything with the meter pointers but I have many years ago refurbished the pointers on my 1957 Chevy dash instruments and it's not an impossible job to repaint them if you're VERY careful and only spray paint very gently. Of course also gently clean out any residue in the rest of the meter but stay away with metallic tools. Some gentle puffs of air with a hand bulb can assist.
Doing this makes the difference between having a meter that looks near new and one that shows those years of residues from smoking (UGH - think what the lungs look like!) and environmental pollution collecting on the glass.
Ian, K6SDE.
I posted this information 2 years ago, but after a few new inquiries (and I see incorrect information on a number of web sites concerning Collins -- including the CCA site)
Bartlett Instrument Company, which was one of original equipment supplier to Collins Radio Company for panel meters in "A" and S-Line equipment.
Simpson Electric, Elgin, IL was another major supplier.
Bartlett Instrument Company
14th Street and Avenue M
Fort Madison, IA 52627
(319) 372-8366 FAX (319) 372-5560
In May 2033, I talked to Rob at Bartlett Instrument Company - Ft. Madison, IA.
I did NOT ask him about what remaining meter parts that Bartlett may have.
They used EMI (no longer in business) and Hoyt for their meter movements
Bartlett NO LONGER PERFORMS REPAIR SERVICES on their analog meters.
The woman who specialized in the analog repair work took ill (severe medical condition) in 2000 and has since retired.
Rob told me that Bartlett sent ALL of the Collins specifications & drawings to Hoyt Electrical Instruments (New Hampshire) - which is where they sourced some of their meter movements.
Bartlett now REFERS ALL of their analog meter repair work to Hoyt
Electrical Instruments Works (NH), one of the largest manufacturers of meters and custom meter movements.
http://www.hoytmeter.com/
I talked to Hoyt shortly after this - BUT they had no specific site on their web site for Collins literature, etc. Possibly the CCA should approach to retrieve copies of these documents?
The Collins 30L-1 meter is very similar to the Simpson Rectangular series model 127, and the larger 3 1/2" model is cross referenced as a Hoyt movement (# 398). Remember that the 30L-1 meter has an "offset" zero position !
Simpson Electric Company in Elgin, IL - Customer Service.
Simpson will normally refer you to one of their repair center across
the country for repairs. This is the web page for repair center look-ups:
http://www.simpsonelectric.com/calnr.htm
Simpson does perform repair work at Elgin, IL for discontinued meters
Simpson Electric Company
Attn: Repair Department
853 Dundee Ave
Elgin IL 60120
Repair costs at Simpson's Repair Center for analog panel meters runs $50
Carlton Bates is another repair center for US. http://www.carlton-bates.com/
Hope this republished update helps.
Maybe someone can follow-up with their personal experience, knowledge or conversations with Hoyt or Simpson regarding Collins meter repairs.
Greg
