Rick (W-A-one-R-K-T) wrote:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

I know that some radios have provisions for installing crystals so that
they'll work on off-band frequencies.

How can I determine which radios are modifiable that way, and also where
is a good place to get crystals these days?


As information, the latest (and greatest?) iteration of the NTIA Red
Book reinforces the spectral purity requirements for the 2-30 MHz band.
The purity specification is currently 40db+10logPo. So, a 100 watt rig
would need to have all spurious emissions down by a nominal 60Db. Most
ham and a lot of commercial gear can't meet that spec. The 20HZ spec
has been on the books for some time, now, and is not hard to meet given
the current crop of equipment utilizing good quality TCXO's. It remains
to be seen what CAP and MARS will do in the short term, and ultimately,
with the spectral purity spec.

Finally, the VFOs in Drake and Collins equipment can't come close to
making any of the above specs or even coming close. Frequency tolerance
is the one factor that can be easily and accurately measured, at a
distance.

Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

I know that some radios have provisions for installing crystals so that
they'll work on off-band frequencies.

How can I determine which radios are modifiable that way, and also where
is a good place to get crystals these days?

Rick (W-A-one-R-K-T) wrote:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

Many will reach the CAP and MARS frequencies at the edges of the
dial.

You can usually make small frequency shifts through modification,
but most ham receivers of the boat anchor class used very frugal
mixing schemes that carefully placed major spurious responses outside
of the ham bands.

Operation around the VFO frequency, or the first IF frequency will usually
not be very nice.

Crystals are readily available from Jan, or ICM. Google is your friend.

-Chuck

I think many ham rigs do not meet the new CAP frequency tolerance
requirements. If you are planning on using the rig on CAP, make sure the
rig is specifically listed as acceptable.

Colin K7FM

"Rick " ) writes:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

I know that some radios have provisions for installing crystals so that
they'll work on off-band frequencies.

How can I determine which radios are modifiable that way, and also where
is a good place to get crystals these days?

CAP and MARS frequencies were (I don't know if it's the case now) generally
chosen to be adjacent to ham bands so ham equipment could be used. There's
little sense of having an auxiliary if the operators have to buy
extra equipment or the organization has to do so.

Remember, they date from before the new fangled equipment came along.
Transmitters were easy, just pop in a suitable crystal and the rest of
the unit would have enough leeway to tune the adjacent frequency. Receivers
were more of a problem, since retuning generally meant retuning the
local oscillator, there weren't always crystals to select the range. But
a receiver that had a bit of overlap was usually okay.

Hence, most equipment would be modifiable, if there wasn't enough overlap.

Michael VE2BVW

On May 7, 9:13 pm, (Michael Black) wrote:
"Rick " ) writes:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

I know that some radios have provisions for installing crystals so that
they'll work on off-band frequencies.

How can I determine which radios are modifiable that way, and also where
is a good place to get crystals these days?

CAP and MARS frequencies were (I don't know if it's the case now) generally
chosen to be adjacent to ham bands so ham equipment could be used. There's
little sense of having an auxiliary if the operators have to buy
extra equipment or the organization has to do so.

Remember, they date from before the new fangled equipment came along.
Transmitters were easy, just pop in a suitable crystal and the rest of
the unit would have enough leeway to tune the adjacent frequency. Receivers
were more of a problem, since retuning generally meant retuning the
local oscillator, there weren't always crystals to select the range. But
a receiver that had a bit of overlap was usually okay.

Hence, most equipment would be modifiable, if there wasn't enough overlap.

Michael VE2BVW

Collins S-Line (which includes KWM-2) is not strictly "ham band only"
in the normal sense of the word. There are 15 or 30 selectable crystal
positions which give a 200 kHz swing in the ranges of 3.4-5.0 and
6.5-30.0 MHz.

It's possible to use an external frequency reference to hit a "dead
nuts on" transmit frequency but for normal use you only have to be
within a designated band limit. There was a crystal accessory
originally intended for Novice ham use when they were rockbound.

Use a counter or service monitor to check your transmit frequency if
you are worried, but I doubt MARS or CAP is going to care if you are
1 khz or less off. Come to think of it, what are CAP's HF allocaions
anyway?

The older equipment referenced, T4/R4, Collins KWM, Collins S-line do not
require any 'modification' to reach the CAP/MARS frequencies. I used the Drake
T4XC/R4C for years, 1970 through 1985, at AFF1C/AFB1JX/AFW1MCE and I used the
KWM-2A at AGA5HI in the 70s. All that is required is the proper mixing crystal.

This class of equipment, however, does not meet the frequency accuracy
requirements so external frequency measuring equipment or a FYMON station was
required to assure accuracy. The output tuned L/C circuits have a minor impact
on the efficiency of the final amplifier. Finally, this class of equipment will
NOT OPERATE in selected frequency ranges around the radio's i.f. frequencies.

More modern equipment can be modified to operate on CAP/MARS. Check the various
use groups for specifics. I have 'opened-up' my IC-746 and IC-706MKIIg without
any problems.

/s/ W1MCE

Rick (W-A-one-R-K-T) wrote:

Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

I know that some radios have provisions for installing crystals so that
they'll work on off-band frequencies.

How can I determine which radios are modifiable that way, and also where
is a good place to get crystals these days?

Rick (W-A-one-R-K-T) wrote:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?


The Collins CP-1 crystal pack provided general coverage HF operation
for the S/Line and KWM-2 equipment. A listing of available
operating frequencies is he
http://www.collinsradio.org/html/s-l...cessories.html

73,
Ed Knobloch

On Tue, 08 May 2007 00:05:35 GMT, "COLIN LAMB"
wrote:

I think many ham rigs do not meet the new CAP frequency tolerance
requirements. If you are planning on using the rig on CAP, make sure the
rig is specifically listed as acceptable.

Colin K7FM


If you look at the list of compliant radios for CAP
https://ntc.cap.af.mil/comm/ you will see that there is almost nothing
in the way of amateur radio equipment that would be useable for CAP.

Dick - W6CCD

--
Posted via a free Usenet account from http://www.teranews.com

On May 8, 9:29 am, Edward Knobloch wrote:
Rick (W-A-one-R-K-T) wrote:
Typically, can ham-bands-only receivers such as the Drake R4 and Collins
75A or 75S series, transmitters such as the Collins 32S and Drake T4
series, and transceivers such as Drake TR-4 and Collins KWM-2, be modified
to work on CAP and MARS frequencies?

The Collins CP-1 crystal pack provided general coverage HF operation
for the S/Line and KWM-2 equipment. A listing of available
operating frequencies is hehttp://www.collinsradio.org/html/s-l...cessories.html


There is a dead band that is not usable on these, 5 to 6.5 MHz. Also
you need a lot of xtals. Even with the expansion board you can only
have if I remember 30 of them.

There were external VFOs that provided all the possible frequencies
for both the xtal osc and the VFO. A Jaapanese company made one. I
think a service monitor will do as well if the output level is high
enough, most have programmable frequencies like scanners. I think if
the weight and size weren't prohibitive the IFR 1500 would be ideal
because it's available cheap and because it has full duplex unlike the
more common 1200/500 series. You could of course just use a sig gen,
again, assuming the level is high enough. No where in the Collins
manuals is the drive level needed specified!

I'm suirprised a digital internal VFO hasn't been devised for S-Line.