The Mighty Philco 37-620
Gary Bernstein
album called "90 Original Old Time Radio Themes." To make a long
story short, this is what hooked me onto collecting old radios. OK,
to the point. On the album cover was a Philco 37-620. I said to
myself "Self, get this radio." So, thirty years later I found one,
brought it back to life somewhat, and am relatively happy. The
question, is it common for the broadcast band (560-1700KHZ) to have a
narrow amount of sensitivity? In other words, why is it no matter how
I align this receiver, sensitivity only stays high within only one
third of the band, let's say from 940-1100KHZ? Am I not aligning this
baby right, or is this component wear? Note, the other two short wave
bands are fine, with sensitivity across the entire band. This is a
strong playing radio, with plenty of guts. I'd sure like to make it
even better. Thanks for your reading, and any helpful advice.
Sincerly, Gary in Coral Springs, Fla.
.Bill :-)
> brought it back to life somewhat, and am relatively happy. The
> question, is it common for the broadcast band (560-1700KHZ) to have a
> narrow amount of sensitivity? In other words, why is it no matter how
> I align this receiver, sensitivity only stays high within only one
> third of the band, let's say from 940-1100KHZ? Am I not aligning this
> baby right, or is this component wear? Note, the other two short wave
> bands are fine, with sensitivity across the entire band. This is a
> strong playing radio, with plenty of guts. I'd sure like to make it
> even better. Thanks for your reading, and any helpful advice.
> Sincerly, Gary in Coral Springs, Fla.
Sounds like an alignment issue. Assuming everything else is
correct...dial readings fairly accurate, etc, there are only 2 trimmers
to adjust for BCB (antenna and mixer) and they should be peaked around
1500kc. If you peak them somewhere else the RF tuning will not track
with the dial tuning across the band.
If you've done that correctly already, hmmm...it would be a weird
problem that I've never encountered. Generally the Philcos of that era
are darn good performers.
-Bill
John Goller, k9uwa
says...
>Generally the Philcos of that era
>are darn good performers.
>-Bill
>
John k9uwa
Gary Bernstein
I think that hit it on the head, aligning the receiver at 1500kc which
I did not do, or come close to doing. A long time ago, someone told
me to align receivers at mid band. I guess that theory was wrong.
I'll give that a try, and appreciate your help. As far as the
trimmers go, I counted three per band, one for antenna, another for
mixer, and the closest to the front cover to align receiver frequency.
I'm going to start from scratch on this old radio, and do it the
right way. Other than that, it's a great set. Thanks again, Gary.
".Bill :-)" <TheRea...@netscape.net> wrote in message news:<3CE86156...@netscape.net>...
.Bill :-)
>
> Bill,
>
> I think that hit it on the head, aligning the receiver at 1500kc which
> I did not do, or come close to doing. A long time ago, someone told
> me to align receivers at mid band. I guess that theory was wrong.
> I'll give that a try, and appreciate your help. As far as the
> trimmers go, I counted three per band, one for antenna, another for
> mixer, and the closest to the front cover to align receiver frequency.
> I'm going to start from scratch on this old radio, and do it the
> right way. Other than that, it's a great set. Thanks again, Gary.
Ok, thats why I qualified my statement with the dial readings being
somewhat accurate before proceeding to peak the ant and mixer. If that
alignment is not correct you might find the trimmers won't go far enough
to achieve good tracking. As John G points out, note that on the osc
there are two adjustments, one for the high end and one for the low end
to get the dial tracking correct.
Anyway, it would be best to zip right thru all 4 of trimmers. These
Philcos generally will have darn good dial accuracy too.
-GL,
Bill
lbrt...@aol.com
> I align this receiver, sensitivity only stays high within only one
> third of the band, let's say from 940-1100KHZ? Am I not aligning this
> baby right, or is this component wear? Note, the other two short wave
> bands are fine, with sensitivity across the entire band.
It is primarily an RF alignment issue, and also possible for an RF cap
or two related to the BC band to be sub-par.
George R. Gonzalez
not the middle. It's sort-of like focusing a zoom lens-- it's not
critical near the mid-zoom, but has to be just right for the high zoom
end to be in focus.
Also a lot of these radios have had the RF coils rewound due to lightning
damage or corrosion-- you may have to rewind them again if you cant get
them to track right.
Gary Bernstein
the upper part of the band, but still leaves the lower dead as a door
nail. At least I can go at this with confidence now knowing I'm
headed in the right direction thanks to you folks. Have a great week
and remember, OLD RADIOS ARE COOL!!
radi...@bellsouth.net (Gary Bernstein) wrote in message news:<6a8bf53e.02051...@posting.google.com>...
Mike Knudsen
very effective and good sounding radio in a practical (wouldn't say small)
package. I bought it from Bob Piekarz long ago near Chicago, after foolishly
selling my Dad's original for $15 back in the 70s.
It has separate antenna, RF, and osc. coils for each band, nine in all, just
like a communications receiver. Calibration really can be to the nearest 10 KC
on the BC band.
Mine seems to have lost much of its sensitivity, especially on BC, so it's
probably time to start checking screen grid resistors. I aligned it when I
first got it, don't think it would have drifted off that much. --Mike K.
Oscar loves trash, but hates Spam! Delete him to reply to me.
John Goller, k9uwa
radi...@bellsouth.net says...
>
>
>Thanks all for your input, and your help. I have tried aligning to
>the upper part of the band, but still leaves the lower dead as a door
>nail. At least I can go at this with confidence now knowing I'm
>headed in the right direction thanks to you folks. Have a great week
>and remember, OLD RADIOS ARE COOL!!
Your problem with alignment is......the 600 Khz Padder.....there are 10 TEN
adjustments to make on this model Philco.....you must follow the sequence
listed in the Riders manual for proper adjustments.......
#1.....the 7.3-22 mhz band.....adjust trimmer part numbers 23b, 8b , 4b
to be set at 18 Mhz.......
#2.....then the 2.3 - 7.4 Mhz band......trimmer part numbers 23a, 8a, 4a to be
set at 7 Mhz....
#3....the BC band parts # 23, 8 , 4 .....with generator set to 1600 Khz.....
then you turn the trimmer part number 21......thats the one thats sort of out
of line with the others.....in the row that has 4 trimmers in it.....
this one has to be set at 600 Khz....turning it will vary the frequency a
little....the alighment instructions tell you to "Rock The Dial" while tuning
the trimmer for Max Signal Level.........an easier way if you have a broadband
noise generator of some kind.....A Soldering Station works WELL for this...as
they really are turning on and off the AC line at a high rate of speed...and
the critters make a lot of hash in a close by AM radio....and it isn't
tunable....this trimmer should have a pretty good peak thats resonably sharp in
tuning.....1/4 turn off and you will miss the max by a mile....if it doesn't
max nicely....then something else is wrong with that curcuit.....assuming that
it does max....then you have to go back and ReTweak the first three parts...
# 23 , 8 , and 4 again.at 1600 Khz...then come back one more time and Re-Do
this
600 Khz trimmer again....and lastly for the third time Re-Do the 1600 ones
as the final adjustment......that should fix the lack of sensitivity in the
lower part of the band unless there is something else wrong with the radio...
Good luck and have fun with it.....it is a nice radio......
John k9uwa
Uncle Peter
to consult a schematic and verify that the antenna input link coil is
not open. What you are describing is close to what happens when
this occurs. There is enough stray capacitance between the adjacent
coil windings for effective coupling on the higher frequencies, but without
the inductive the signals at the low end of the band will be extremely
weak in comparision.
Pete
"Gary Bernstein" <radi...@bellsouth.net> wrote in message
news:6a8bf53e.02052...@posting.google.com...
.Bill :-)
>
> I remember when I was a kid back in the late sixties, I bought this
> album called "90 Original Old Time Radio Themes." To make a long
> story short, this is what hooked me onto collecting old radios. OK,
> to the point. On the album cover was a Philco 37-620. I said to
> myself "Self, get this radio."
There's one of those albums on ebay...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2104244851
-Bill M