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don't have key s as part 01 our

ham station or who are essentially

lazy. We don 't have the

power to compete w ith Radio

Moscow to C RM them, but radar

depends on receiving an echo

lor its results and that echo

can' t possibly be a match for a

ham kW beamed in the right direction

with a similar signal. All

one has to do is tape record a

few minutes of the woodpecker

and play it back al them!

If all the " tuner uppers" and

" pileup" participants wou ld get

together on a "Woodpecker's

Sunday" and send out the taped

sig nal a ll over the band at the

same time, perhaps they might

get the message.

The o ther is your story, " Over

the Hump" and the references

to AC4YN. Of course , before the

war AC4YN was the legendary

contact that you had 10 work to

gel Zone 23. Your article mentions

Regg ie Fox as AC4YN , but

I have reason to believe that it

was a British Army group operetions

and that there were others

that used the call either before

or after Regg ie.

I served In Ita ly during WWII

at AFHQ Ita ly in a combined US

Signal CorpS/Royal Signals operation,

which has made me

eligible for membership in the

Royal Signals Amateur Radio

Society. Currently, there are

about ten U.S. hams who belong

to RSARS. I got a life membership

back when the pound was

worth $1 .80.1 geta lot of m ileage

out of that connect ion with

QSOs with " G" statio ns. At the

time I Joined, o ne of the officers

was Sir Evan Neppan G5YN .

There was quite a story on Sir

Evan In the Society publication,

Mercury. He was a career officer

in the Brit ish Army, had operated

from exotic spots all over

the world, and had been knight·

ed by the Queen. It appears that

o ne of the ca lls he had held was

AC4YN , so you figure that out! I

had a nice leller from him when I

joined and have worked him on

the air.

Col. Edson B. Snow, AUS Ret.

Pompano Beach Fl

from page 30

ed a measu re of additional gain.

Our basic d ownconverters

soon acquired an elaborate

"look" which reminded us of a

mi ni·TVRO setup, and we somehow

fe lt we had set new OX

records for solid MOS reception

in this heavily wooded and

mountainous area of the United

States. One aspect has definite­

Iy proven true: Signal paths

which are not line of sight are

difficult to predict and use. Rais·

ing antenna height to acquire

line of sight is often the only

logical alternative.

Some additional members of

our group decided to co nstruct

co mpetit ive and more expensive

downconverters , reasoning that

complexity and cost should provide

better results. Unfortunately,

we did not lind that true and

had to work like heck to get

marginally acceptable resu lts

from th ose units. Our previo usly

acquired knOWledge of microwave

construction techniques

REVIEW

was also required to supplant

marginal Instructions used with

these units.

Fortunately, however, we all

came out w inners at th e end

and except for me, everyone is

pre sently enjoying watching

special TV prog rams. My carneurer

converter works great, but

I'm 20 m iles, two mountains,

and o ne dense forest from the

MOS transmitter. Plans include

wrestling a a.s-toot parabolic

dishldownconverter setup to the

to p o f an 8O-foot pine tree and

adding a second TV tuner bet

ween the converter and the

te levision for additional gain.

We're not giving up yet!

In conclusion, the Universal

Communications oownccnverter

kits have proven their worth

and are very reliable units. If you

would like to get your feet wet in

microwave, MOS, or weather

satellite reception. these units

are a good starting point. At the

present time, I'm al so ccnsioering

the feasibility of modifying a

unit for TV satellite reception.

Realis tic DX·200 communication receiver.

A number of additional items

also will be requ ired, but a work·

ing system fo r under S400 looks

very promising.

The o riginal oownccnverter

board described here is avanable

from Universal Communi·

cations, Box 6302, Arlington TX

760 " .

Dave Ingram K4TWJ

Birmingham Al

DX·200 RECEIVER

The OX·200, so ld by Radio

Shack. is a general-coverage

receiver. It tunes five bands: 150

kHz to 400 kHz, 520 kHz to 1.6

MHz, 1.55 MHz to 4.5 MHz, 4.5

MHz to 13 MHz, and 13 MHz to

30 MHz. It is designed for the

receptio n of the three mostused

forms of amplitude-modu·

rat ed si gnal s, which are double

sideband with carrier (AM , or

6A3), single sideband without

carrier (SSB , or 3A3j), and makeand-break

radiotelegraphy (CW,

orO.1A1). The basic design is the

c lassic single-conversio n superheterodyne

with an intermedi·

ate frequency u.n of 455 kHz.

The circuit provides one stage of

preselection before the Irequency

conversion.

To evaluate this receiver, it

was com pared with two others,

each o f recognized performance

capability but of other design

and in a higher cost bracket. A

coaxi al swi tch was used to

switch the reference antenna

among t he three receivers,

thereby ensuring a comparable

signal to each. In addition to ottthe-air

sig nals, a URM·25D signal

generat or was used to make

measurements o f sensitivity

and of image rejection.

One 01 the comparison receivers

wa s a Yaesu Model

FRG·7, which uses the Wadley

l oop system. This invo lves trio

pie co nversion, with a first i·f of

55 MHz, to ensure almost total

freedom from images. The o ther

was the receiver sectio n of a

Kenwood T8-1205. This is a

single-co nversion receiver with

an I·f 01 8.8 MH z. Unless etherwise

stated, ott-tne-alr signals

were obtained Irom an 8O-meter

trapped dipole antenna mounted

50 feet above ground.

Initiatly, the OX·200 wa s tuned

to the AM broadcast band. Here

It performed very well indeed.

Both selectivity and sen sitivity

were excellent, and the stability

adequate. I rated it on a par with

the FRG·7 with but one exception.

W ith the rf gai n control

turned fUlly on, the set broke tnto

oscillation, causing severe

distortion. Backing off s lig htly

o n the gain co ntrol stopped th e

distortio n. With a short indoor

antenna, the rf gain could be advanced

fU lly without d istortio n.

The second c heck was on the

longwave band. The OX·200 did

qu ite well. It is o ne of the very

few lo ng wa ve receivers I' ve

heard that doesn't bring in local

broadcast band stations almost

as loudly as LF stations! There

was some slight spillover but

not enough to be troublesome.

In the high·frequency range,

the receiver displayed varying

degrees of performance. For the

receptio n of shortwave BC etations,

it dId quite well over the

whole spectrum, fUlly equa ling

the FRG·7 in all respects save

o ne: Image rejectio n above 5 or

6 MHz is very poor. The selectivity

and sensitivity were fully adequate

for SW U ng and I didn't

notice any frequency drift. Even

the sponginess of the bandspread

d ial was not too c ojectionable.

For the reception of HF sse

stations, the level of pertermance

dropped. In the MF

t ee-meter band and in the HF

80- and 4O-meter bands, si gnals

could be demodulated with ac-

124 73 Magazine . April,1981

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