WA8ULG - Ted

Parks-Flagstaff, AZ

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Latest addition to the WA8ULG menagerie is an Arizona-produced Kachina 505DSP transceiver.  This unit incorporated many features later made famous by SDR's and IF-DSP commercial radios.

(Click here or image at left for photographs)



    

 


The current Big Project at WA8ULG: converting a Collins 820 D2 1-kW broadcast transmitter to HF operation on 160, 80 and 40 meters. The 820 D2 ("The Rock") runs a pair of 5-500's in the final, modulated by a pair of 5-500's.

Notable ancillary equipment in rack at left: frequency-synthesized RF exciter, GR modulation monitor, a Shure Audio Master mike preamp/driver and a 3-band, IMP-3 compressor/limiter. the latter two units comprising the audio chain.

(Click here for larger photo  ~100K)








   


The Tank is a Pi-L using an effective 1100 pF Plate C, 15 uHy, motor-driven variable L and 4000 pF Load C.  The coil on the floor of the tank box is the L of the Pi-L; it is fixed in each band.  The PA Tank covers 160/75 and, tentatively, 40.  The Plate C is a 2000 pF in series with the 4000 pF vacuum variable that nicely opens the range up over the nominal tuning for 160 and 75.  When typically run at 3855kHz, component values are: 400 Pf Tune, 5uHy and 1700 Pf Load.  

(Click here for larger photo ~100K)






Driver input circuitry:  A Philips PM-5192 Synthesizer is used as the oscillator.  It comes into the box at TTL levels.  A 74xx something drives a 2N3866 that, in turn, drives an MRF-150 FET which drives the final grids through the input transformer. The 160 input transformer is the original coil cut down; the 75 coil is new and on the Delrin pier shown to the right.  Everything switches, the primary on the left side of the relay and the secondary on the right side. The 40-meter section is yet to be installed.

(Click here for larger photo ~100K)




The Tuning and Loading controls:  The two multi-turn knobs control the plate-tuning cap (top) and the loading cap (bottom).  The bat-handle switch in the old PA tune hole operates in conjunction with the little edgewise meter to control and follow the Pi inductor (15 uHy).  The front panel unlabeled knob to the right of the load multi-turn is the band switch.

(Click here for larger photo ~100K)





Posthumous Statement by Art Collins, W0CXX, Concerning This Modification







A subassembly in the Nye-Viking tuner falls victim to the plasma-generating CW power of "The Rock", as well as its asymmetric, positive-modulation capability.


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The latest addition is a Radio Engineering Associates AMM-HF1 modulation monitor, situated between the Collins 51J4 receiver and the Philips frequency synthesizer.  


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Click on Icons at left to see Mod Monitor and 51J4 in action with WWV signal.







A product shot of the REA AMM-HF1.  This unit displays both positive and negative modulation levels on the two, green LED "meters".   It can be used to measure transmitted and received signals, although the latter requires additional IF amplification.


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Click here to go to the REA website





Modulation Monitor Scopes for free (almost)

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The complete WA8ULG AM rig:  (r-l) receiver/mod monitor/synthesizer (vfo); 820D2 xmtr; audio rack.

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The audio rack:  GR 1931 modulation monitor, Shure Audio Master mike preamp/driver, decade-adjustable audio pad and a 3-band, IMP-3 compressor/limiter. 


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WA8ULG at the mike.  5-500 finals and modulators shown, as well as modded RF-driver circuitry. 


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WA8ULG at the mike of a Clegg Zeus / Interceptor combination owned by his local club back in the 1960's.  Ted now owns a Zeus and Interceptor, courtesy of W7MD, but has substantially less hair.  


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FORT TUTHILL redux


WA8ULG leads the charge to return the ARCA hamfest to Flagstaff (Ft. Tuthill).  Read all about it here....


"Here is the new 32V3 I captured from KBLOQ with a 75A3-- a pair of three's.  cute little 1" Millen for mod scope and a new eBay EV 719 to look like the 50s" - Ted WA8ULG

This is the operating position in 'Studio B', the horse house.

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The big snowstorm of 2010 hits the high-prairie QTH of WA8ULG and the OM and XYL are delightfully snowbound.  The drifts almost cover the door and windows of the horse house,  aka 'Studio B', about 300 feet from the main house.

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Ted takes the measure of one of the two modulation transformers used by WLW's 500 kW broadcast transmitter. It gives the term "heavy metal" a whole new meaning.

 

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Ted has twice made the pilgrimage to the WLW transmitter site to view the 500 kW transmitter as part of the Dayton Hamvention.  The trip was organized by Geoffrey Mendenhall, W8GNM, who also compiled a CD of data about the station. 

Clicking on this link, or on the image at left of Powel Crosley Jr. at the controls of the 500 kW rig, takes you to an on-line excerpt from Geoff's compilation.






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